Two IUD devices side by side neutral background

Mirena vs Paragard: Side Effects and Risks Compared

On By Dr. Scott RennieIn Menopause & Women's Health1 Comment

I do not place IUDs. I practice entirely by video, so what I actually do is have the conversation, help someone decide which device they want, and send them somewhere to have it put in. That turns out to be most of the work anyway. By the time a patient reaches the procedure room the decision has usually already been made, often on the basis of something a friend said.

So this is the conversation, written down.

Two devices that have almost nothing in common

People talk about “getting an IUD” as though it were one thing. Mirena and Paragard sit in the same place and prevent pregnancy about equally well, and past that they behave like different drugs, because one of them is a drug and the other is a piece of copper.

Mirena releases levonorgestrel, 52 mg in the device, locally into the uterus. It thickens cervical mucus, thins the endometrium, and suppresses ovulation inconsistently. The FDA extended its contraceptive approval to eight years in August 2022, based on extension-trial data showing efficacy above 99 percent through years six to eight (1, 2). Its separate indication for heavy menstrual bleeding runs five years, not eight, which trips people up.

Paragard is a copper T380A. No hormone at all. Copper ions are toxic to sperm and change the intrauterine environment enough to prevent fertilization. Approved for ten years (3).

The bleeding difference, which is what people actually care about

This is the fork in the road, and everything else is secondary.

Mirena makes periods lighter. Progressively so. A meaningful minority stop bleeding altogether within the first year, and many others go down to spotting. For someone whose periods are ruining a week of every month, that is the point of the device, not a side effect of it.

Paragard does the opposite. Heavier flow, more cramping, particularly in the first three to six months. It settles for most people. It does not settle for everyone, and it is the most common reason the copper device comes out early.

So the first question is not which device. It is what your periods are like now and what you would like them to be. Answer that and the device usually picks itself.

What people worry about, in the order they raise it

Hormones. Mirena’s levonorgestrel acts mostly locally, and systemic levels are far below what a combined pill delivers. That does not mean nobody has systemic effects. Some patients report mood change, breast tenderness or acne, and I do not tell them it cannot be the device. The honest statement is that the systemic exposure is low, the trials do not show a consistent mood signal, and individual experience still counts.

Insertion pain. This got taken seriously very late. Patients were told for decades it would be a pinch. It is not a pinch for a lot of people, particularly if they have never been pregnant. Ask the placing clinician directly what they offer for pain, before the appointment, not at the appointment.

Perforation. Roughly one per thousand insertions, and higher in someone who is postpartum and breastfeeding.

Expulsion. A few percent, most often in the first year and most often around a period.

Infection and fertility. The elevated infection risk is confined to about the first twenty days after insertion, which is a placement-related event rather than an ongoing property of the device. Neither device causes infertility. That belief traces back to the Dalkon Shield in the 1970s, a badly designed product withdrawn fifty years ago, and it is still costing people options today.

Emergency contraception, where the answer changed

The copper IUD was the most effective emergency contraceptive available, full stop, if placed within five days. That was true for a long time and it is still true.

What changed is that the levonorgestrel 52 mg IUD is now an option there too. Turok and colleagues published a randomized noninferiority trial in the New England Journal in 2021 showing the LNG device was noninferior to copper for emergency contraception (4). That matters practically, because it means someone who wants ongoing lighter periods no longer has to accept the copper device just to cover the emergency need.

The perimenopausal use nobody mentions

This is the part of the topic I see most, given what I spend my days on.

A woman in her forties with heavy, unpredictable bleeding is often handed a choice between ablation, hysterectomy and waiting it out. The levonorgestrel IUD belongs in that conversation and frequently is not in it. It treats the bleeding, it covers contraception during the years when fertility is low but not zero, and if she later goes on systemic estrogen for vasomotor symptoms, it provides the endometrial protection that estrogen requires.

One device, three jobs.

Most of the time it has not been discussed yet when the subject comes up with me. Part of that is age. These patients are older, and if they have thought about an IUD at all it was as birth control, twenty years ago, in a different phase of life. Nobody has framed it to them as a treatment for the bleeding they are actually calling about.

For patients

Decide what you want your periods to do, then pick the device. Lighter or absent points to Mirena. No hormones at any cost, accepting heavier periods, points to Paragard.

Ask whoever is placing it what they offer for pain control, and ask before the day. If you are in your forties and bleeding heavily, ask specifically whether the hormonal IUD would treat that, because it may not come up otherwise.

For colleagues

The eight-year contraceptive approval and the five-year heavy-bleeding indication are different numbers on the same device, and patients are being told one or the other at random.

Bring the LNG-IUD into perimenopausal bleeding conversations earlier. The path from heavy bleeding to ablation still skips it more often than it should.

The Bottom Line

Both devices prevent pregnancy better than almost anything else available, so effectiveness is not the deciding factor. Bleeding is. Mirena makes periods lighter and is approved for eight years of contraception and five years of heavy-bleeding treatment. Paragard is hormone-free, lasts ten, and makes periods heavier. The old fear that an IUD will cost you your fertility comes from a product pulled from the market in the 1970s and should not be steering anyone’s decision in 2026. If you are in your forties with heavy periods, ask about the hormonal one specifically.

Related Reading

Perimenopause and Menopause Symptoms and How to Manage Them

FDA Removes Black Box Warning From Menopause Hormone Therapy

Why Menopause Care Is Missing From Women’s Checkups

Menopause Treatment by Telemedicine: How It Works

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Sources

1. Mirena (levonorgestrel-releasing intrauterine system) prescribing information. Bayer HealthCare Pharmaceuticals. FDA label, 2022. https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/021225s043lbl.pdf

2. Bayer. Mirena approved in the US for extended duration of use in contraception. August 2022. https://www.bayer.com/media/en-us/mirena-from-bayer-approved-in-the-us-for-extended-duration-of-use-in-contraception/

3. Paragard T 380A (copper) intrauterine device prescribing information. CooperSurgical. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3c420b53-c95e-46af-aebd-73741be58391

4. Turok DK, Gero A, Simmons RG, et al. Levonorgestrel vs. Copper Intrauterine Devices for Emergency Contraception. N Engl J Med. 2021;384(4):335-344. PMID 33503342. https://pubmed.ncbi.nlm.nih.gov/33503342/

Medical alert bracelet with allergy and diabetes information next to round alarm clock on bedside table

First Aid for seizures

On By Dr. Scott RennieIn NeurologyLeave a comment

When people ask about first aid for seizures, I usually start with the basics. Carry medical identification. If an emergency happens, it helps bystanders and providers know you have a seizure disorder and what to do next. Family, friends, and coworkers should also know how to respond. Safety comes first, and the details matter.

It’s important to think about daily risks. Someone with uncontrolled seizures should be cautious around high places, moving equipment, hot stoves, or machinery. Staying active is still encouraged, but some activities call for extra planning. Swimming, climbing, or gymnastics are safer when another person is present who understands seizures and knows basic life-saving skills. Even routine things like bike riding or canoeing can be made safer with helmets and life jackets.

Medication is another cornerstone. If you’ve been prescribed an anticonvulsant, don’t stop it suddenly or change the dose without talking to your doctor. The exact drug and dose depend on the type of epilepsy and factors like weight, age, and other health conditions. Watch out for drug interactions, including with over-the-counter medications. Pharmacists are a good resource when you’re not sure. Alcohol should also be avoided since it can interfere with seizure control.

If someone has a seizure, the steps are simple but crucial. Loosen anything tight around the neck. Move sharp objects away to reduce injury risk. Don’t try to hold the person down. Don’t put anything in the mouth. Let the seizure run its course. When it’s over, place the person on their side so the airway stays clear. Often, there’s confusion after the event, so it helps to stay close until they’re fully awake.

Not every seizure requires a trip to the hospital. If it ends in a minute or two and the person has a known diagnosis of epilepsy, observation may be enough. Call an ambulance if the seizure lasts more than five minutes, if seizures repeat without recovery in between, or if the person doesn’t regain awareness. Extra caution is needed if there are other medical conditions such as diabetes or heart disease.

Children can have many types of seizures, and the approach shifts depending on what you see. With a generalized tonic-clonic seizure, keeping the airway open and the head protected are priorities. With absence seizures, observation and careful note-taking matter more. If awareness is altered but movements continue, guiding the child to a safe place is often the best step. Any first seizure in a child should prompt medical evaluation, and some types such as infantile spasms need urgent attention.

Education matters as much as medication here. Bystanders who know to move objects away, stay calm and wait it out change how the whole event goes.

This is for general information only and not meant as medical advice for an individual patient. If you or someone you love has seizures, discuss a personalized plan with your healthcare provider.

Wishing you the best of health,

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Source:

DNA strand with labeled growth hormone pathway steps next to an hourglass at sunset

Does the Laron Syndrome Gene Mutation Hold Keys to Longevity?

On By Dr. Scott RennieIn Longevity & Healthy AgingLeave a comment

There is a group of people in the southern Ecuadorian provinces of Loja and El Oro who almost never get cancer and almost never get diabetes. They are also, on average, about four feet tall.

Both facts have the same cause, and the story has been badly told for fifteen years. It gets written up as a longevity discovery. It is not one, and what it actually is turns out to be more interesting.

What the mutation does

Laron syndrome is a mutation in the growth hormone receptor. The pituitary makes growth hormone normally. The body cannot hear it. Since most of growth hormone’s effect on tissue runs through IGF-1, and IGF-1 production depends on that receptor working, people with the mutation have very low circulating IGF-1 from birth. They are short. Severely so, and untreated adults reach heights well below any normal range.

The Ecuadorian cluster is the largest known population with it, descended from a founder effect in a relatively isolated region.

The numbers that made people pay attention

Jaime Guevara-Aguirre followed roughly a hundred of these individuals for 22 years and published with Valter Longo’s group in Science Translational Medicine in 2011 (1).

Among the affected subjects: one nonlethal malignancy, and no cases of diabetes. Among their unaffected relatives, living in the same villages, eating the same food, drinking the same water: 17 percent cancer prevalence and 5 percent diabetes (1).

That is not a subtle effect. Not a hazard ratio you argue about. Essentially zero versus roughly one in six.

The metabolic picture explains the diabetes half. Fasting insulin in the affected group ran 1.4 µU/mL against 4.4 in relatives, and HOMA-IR was 0.34 against 0.96 (1). They were markedly more insulin sensitive, and this despite a high prevalence of obesity in the group, which is the detail that should make anyone who works in metabolic medicine sit up.

The cancer half is less settled. When the investigators treated human mammary epithelial cells with hydrogen peroxide in the presence of serum from affected subjects, they saw fewer DNA breaks and more apoptosis of damaged cells, along with reduced expression of RAS, PKA and TOR and increased SOD2 (1). Damaged cells being cleared rather than surviving to divide.

Here is the part that gets left out

They do not live longer.

People with Laron syndrome in this cohort live about as long as their unaffected siblings. The protection from cancer and diabetes is real and it does not translate into extra years, because the deaths come from elsewhere: accidents, alcohol-related causes, and convulsive disorders appear disproportionately (2).

So the honest summary is that this mutation removes two of the diseases that kill most of us, and the years get spent anyway. Which is a lesson about longevity research generally. Compressing morbidity and extending lifespan are different outcomes, and a study that shows one is routinely reported as showing the other.

A 2024 follow-up from the same group looked at cardiovascular risk in these subjects and found markers that were normal or better than their relatives (3), and earlier work has reported delayed age-related cognitive decline (3). The healthspan signal keeps holding up. The lifespan signal was never there.

Why this matters if you are not four feet tall

The obvious wrong conclusion is that low growth hormone is good and we should all have less of it. Nobody is proposing to give people this mutation.

The useful conclusion runs the other direction, at the anti-aging clinics selling growth hormone injections to men in their fifties. The GH and IGF-1 axis, pushed up, is the same axis that is pushed down in the population with almost no cancer. That does not prove supplemental growth hormone causes cancer in a 55-year-old, and I am not going to claim it does. It is a reason to ask what evidence exists that pushing the pathway the other way is safe over decades.

The other thread worth following is nutritional. The pathways involved here, IGF-1, TOR, PKA, are the same ones that respond to protein intake and to fasting, which is why Longo’s laboratory went from this cohort to fasting-mimicking diets. I have written elsewhere about what the fasting evidence does and does not support, and the short version is that the mechanism is well-motivated and the human outcome data is thinner than the enthusiasm.

The Bottom Line

A hundred or so people in southern Ecuador carry a growth hormone receptor mutation that appears to make them nearly immune to two of the most common chronic diseases in the world. One nonlethal cancer and zero diabetes in the affected group, against 17 percent and 5 percent in their own relatives. They do not live longer for it. That combination, better healthspan without longer lifespan, is the actual finding, and it is worth more than the version that gets headlined. If anyone offers you growth hormone as an anti-aging therapy, this cohort is the reason to ask what evidence they have that pushing that pathway up is safe.

Related Reading

Longevity Medicine: What Actually Works, and What Doesn’t

Does Fasting Slow Aging? What the Science Says

How Does Aging Change Your Metabolism? What Research Shows

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Sources

1. Guevara-Aguirre J, Balasubramanian P, Guevara-Aguirre M, et al. Growth hormone receptor deficiency is associated with a major reduction in pro-aging signaling, cancer, and diabetes in humans. Sci Transl Med. 2011;3(70):70ra13. PMID 21325617. https://pubmed.ncbi.nlm.nih.gov/21325617/

2. Guevara-Aguirre J, Guevara A, Palacios I, et al. Insights from the clinical phenotype of subjects with Laron syndrome in Ecuador. PMID 33047268. https://pubmed.ncbi.nlm.nih.gov/33047268/

3. Guevara-Aguirre J, Mishra A, Canepa M, et al. Normal or improved cardiovascular risk factors in IGF-I-deficient adults with growth hormone receptor deficiency. Med. 2024;5(7):816-825.e4. PMID 38677286. https://pubmed.ncbi.nlm.nih.gov/38677286/

Tablet showing a heart-shaped home medical service logo with a red cross and play button.

Watch Dr. Rennie’s New Video for Rennie Family Health

On By Dr. Scott RennieIn Healthcare System & TechnologyLeave a comment

Check out my new video for Rennie Family Health:

 

Spintext.com helped me create it, and they do excellent work. If you’re looking for an organization to help promote your practice with video or websites, I highly recommend them!

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

COVID-19 vaccine vial labeled sterile suspension next to a shield emblem on a wooden table in a lab

King County Flu Update: Influenza Activity in Feb 2011

On By Dr. Scott RennieIn Infectious DiseaseLeave a comment

It’s still recommended that healthcare providers continue to actively recommend influenza vaccination for everyone six months of age and older.

Public Health Seattle & King County reported in February 2011 that flu was still circulating in the area during week 5, though at lower levels than what we typically see during peak seasons. Looking back, in three of seven influenza seasons since 2002, flu activity didn’t peak until March or even later. The exception, of course, was the 2009 H1N1 outbreak, which followed a very different pattern.

On the national level, the CDC found that the current trivalent vaccine was well-matched to the strains circulating at that time. That match between vaccine and circulating virus is one of the key factors in how much protection we see across the community.

Seasonal flu patterns can be unpredictable. Some years activity drops early, while other years it lingers into spring. The important takeaway is that flu vaccination still matters late in the season. Patients often ask if it’s worth getting the shot in February or March. The data suggest that it is, especially since later peaks are not unusual.

For more information and regular updates, you can check local and national resources:

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Tissues, tea mug, thermometer on cozy blanket

Cold vs Flu vs COVID vs RSV: How to Tell Them Apart

On By Dr. Scott RennieIn Infectious Disease1 Comment

This post used to be a comparison of the common cold, seasonal flu and H1N1 swine flu. That framing is fifteen years out of date, and keeping it would be misleading in a specific way: H1N1 is no longer a separate thing to tell apart from seasonal flu. The 2009 pandemic strain settled into circulation as one of the ordinary seasonal influenza A subtypes, A(H1N1)pdm09. When you get influenza A now, that is frequently what it is.

The four illnesses actually worth separating in 2026 are cold, influenza, COVID-19 and RSV.

The honest answer first

You cannot reliably tell them apart from symptoms. Neither can I, over video, and neither can anyone in an exam room with a stethoscope and a light and all the time in the world, which is worth saying plainly because patients arrive having read a symptom chart and expecting me to run their answers through it and hand back a name.

That is not a limitation of describing symptoms carefully. All four are respiratory viruses that produce overlapping illness, and the overlap became worse rather than better once COVID stopped presenting the way it did in 2020. Loss of smell was a useful discriminator for about a year and then largely stopped being one.

So everything below is about probabilities and about what changes your management, not about a checklist that gives you an answer.

What each one tends to look like

A cold builds. Over a day or two, it goes sore throat, then congestion and runny nose, then cough. Fever is uncommon in adults. You feel unwell and you keep functioning.

Influenza arrives. People remember the hour. Fever, headache, aching muscles, exhaustion out of proportion to the respiratory symptoms, dry cough. The abruptness is the most useful single feature, and it is still only suggestive.

COVID-19 in 2026 mostly looks like a bad cold with more fatigue and a more persistent cough, often with a sore throat that patients describe as worse than the rest of it. Onset is usually less abrupt than flu.

RSV in adults gets missed constantly because everyone files it under a childhood illness. In an older adult or someone with COPD or heart failure it presents as wheeze, worsening breathlessness and a cough that will not clear, frequently without much fever. If a patient over 65 with lung disease has been coughing and wheezing for a week, RSV belongs on the list.

Why testing is worth it now, when it was not in 2011

The old advice was that testing rarely changed anything. That was fair when the treatments were marginal.

It is no longer fair, for one reason: there are time-limited treatments, and the clock starts at symptom onset.

Oseltamivir works best started within 48 hours (1). Baloxavir is a single dose, and the trial that established it in adults and adolescents also enrolled within 48 hours of symptom onset (2). For COVID, nirmatrelvir and ritonavir is a five-day window from symptom onset in people at higher risk. Miss the window and the conversation becomes supportive care.

Combination home tests that read out COVID and influenza A and B from a single swab are now available over the counter. They are less sensitive than what a lab runs, particularly early, and a negative on day one in someone who clearly has influenza is a false negative more often than it is reassurance. A positive is useful. A negative in a sick person is not an all-clear.

The practical consequence: if you are in a group where antivirals are worth having, test early rather than waiting to see how it goes. Waiting is what closes the window.

What I do with this over video

I ask when it started, and I ask for the hour rather than the day, because abrupt onset is the most discriminating piece of history available and people can usually place it.

I ask what the household has. In a season, the household is often better evidence than the symptoms.

I ask about breathing rather than about cough, because cough is universal and shortness of breath is what separates the people who need to be seen. Anyone reporting new breathlessness at rest, chest pain, confusion, or an inability to keep fluids down gets routed out of the video visit, and my order of preference is primary care first, urgent care next, emergency department when it needs to be. Primary care is the hardest of the three to get into quickly, which is exactly the problem.

On the vaccines

All four illnesses here have a prevention story, and three of them have vaccines. I am deliberately not listing eligibility ages in this post, because the authoritative source for those is the CDC schedule and I will not publish vaccine ages under my license on the strength of a secondary source. Ask your pharmacist or your physician, and see my separate post on this season’s COVID vaccine for the version of that conversation I can source properly.

For patients

If it hit you all at once and you feel like you were run over, think influenza and test today rather than tomorrow, because the treatment window is 48 hours.

If it built up gradually and mostly involves your nose and throat, it is probably a cold and there is nothing to take for it.

If you are older or have lung disease and you have been wheezing for a week without much fever, ask specifically about RSV.

A negative home test on the first day means very little. Call about breathing, not about cough.

For colleagues

Adult RSV is the one being missed. It gets called a COPD exacerbation or an atypical pneumonia and never gets tested for, and the epidemiology suggests it is a good deal more common in older adults than our diagnosis rate implies.

Antiviral time windows deserve to be said out loud to patients before they are sick, particularly in the higher-risk groups. Patients who know there is a clock behave differently in the first 24 hours.

The Bottom Line

H1N1 is not a separate illness any more, it is one of the ordinary seasonal influenza A subtypes, and that is why this post needed rewriting. Cold, flu, COVID and RSV cannot be reliably separated by symptoms, and the abruptness of onset is the only feature that carries much weight. What has genuinely changed since 2011 is that testing now changes management, because oseltamivir and baloxavir want to be started within 48 hours and the COVID antiviral within five days. If you are going to test, test early. Waiting is the mistake.

Related Reading

Do I Have the Flu? Common Influenza Symptoms Explained

2026-2027 COVID Vaccine: Who Qualifies, and Do You Need a Doctor’s Note?

Flu Prevention: Vaccines, Symptoms, and Treatment Options

Why Won’t Antibiotics Cure a Viral Infection? Doctor Explains

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Sources

1. Uyeki TM, Bernstein HH, Bradley JS, et al. Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenza. Clin Infect Dis. 2019;68(6):e1-e47. PMID 30566567. https://pubmed.ncbi.nlm.nih.gov/30566567/

2. Hayden FG, Sugaya N, Hirotsu N, et al. Baloxavir Marboxil for Uncomplicated Influenza in Adults and Adolescents. N Engl J Med. 2018;379(10):913-923. PMID 30184455. https://pubmed.ncbi.nlm.nih.gov/30184455/

3. World Health Organization. Influenza (seasonal) fact sheet. https://www.who.int/news-room/fact-sheets/detail/influenza-%28seasonal%29

Glass of ice-filled soda with heartbeat and heart graphics on table

Does Diet Soda Raise Stroke and Heart Attack Risk?

On By Dr. Scott RennieIn NeurologyLeave a comment

Someone switches from regular soda to diet soda, feels reasonably good about it, and then reads a headline saying diet soda causes strokes. That has been the pattern for about fifteen years now, and the evidence underneath it has moved enough to be worth going through properly.

Where the scare started

The original signal came from the Northern Manhattan Study. Gardener and colleagues followed 2,564 people for a mean of ten years and counted 591 vascular events, meaning stroke, myocardial infarction or vascular death. People drinking diet soft drinks daily had a hazard ratio of 1.43 compared with people drinking none, with a confidence interval of 1.06 to 1.94 (1).

What made it interesting is that the association held after adjusting for metabolic syndrome, diabetes, hypertension, cardiac disease and hypercholesterolemia, and that regular soft drinks showed no such association in the same cohort (1).

A confidence interval running from 1.06 to 1.94 is a study saying “something is probably here, and we cannot tell you how big.”

What came after

The Women’s Health Initiative analysis in 2019 is the one that made me take this more seriously. 81,714 postmenopausal women. Those consuming two or more artificially sweetened beverages a day, compared with less than one a week, had a hazard ratio of 1.23 for all stroke, 1.31 for ischemic stroke, 1.29 for coronary heart disease and 1.16 for all-cause mortality (2).

The subgroup finding is the one that sticks. In women with no prior cardiovascular disease and no diabetes, high consumption was associated with more than double the risk of small artery occlusion ischemic stroke, hazard ratio 2.44 (2). That subgroup matters precisely because it is the group where reverse causation is least likely to explain the result.

Then erythritol. Witkowski and colleagues published in Nature Medicine in 2023, working across a discovery cohort of 1,157 patients and US and European validation cohorts of 2,149 and 833. Circulating erythritol in the highest quartile was associated with increased three-year risk of major adverse cardiovascular events, and they followed it with mechanistic work on platelet reactivity (3).

Erythritol is not aspartame or sucralose. It is a sugar alcohol used heavily in stevia and monk fruit blends and in a great deal of what gets sold as keto-friendly. Somebody avoiding artificial sweeteners on principle may be consuming more erythritol than anyone in that study.

The problem with all of it

Reverse causation. It is the whole difficulty and it does not go away.

People do not drink diet soda at random. They drink it because they are worried about their weight, or because someone told them to cut sugar, or because they already have diabetes. So a cohort of daily diet soda drinkers is enriched for people who were already heading toward a vascular event before they ever opened a can. Statistical adjustment helps and does not fix it, because you can only adjust for what you measured.

There is no randomized trial showing that drinking diet soda causes strokes. There is not going to be one. The trials that do exist are short and use intermediate endpoints, and they generally show that substituting a sweetened beverage for a sugar-sweetened one produces modest weight loss.

The World Health Organization landed on this in 2023 and issued a conditional recommendation against using non-sugar sweeteners for weight control, on low-certainty evidence, noting possible long-term associations with type 2 diabetes and cardiovascular disease (4). Conditional and low-certainty are doing real work in that sentence. It is not a ban and it was not presented as one.

What I think this adds up to

Diet soda is not established as a cause of stroke. The associations are consistent across several large cohorts, which is more than nothing, and they are exactly what confounding by indication would also produce, which is why nobody has closed the case.

Here is what I tell patients, and I separate it by what they came in for.

If you have diabetes, diet soda does not spike your blood sugar the way regular soda does. So if you are not going to give up soda completely, diet is the better of the two, and I would rather you drink it than pretend you are going to stop.

That is the whole of the defense. Diet soda is not healthy, and we know that. Some of what is in it has been linked to health problems, which is most of this post. And there is a second issue that matters more in a weight-management visit than the vascular question does: some research suggests diet soda makes you hungrier.

Yunker and colleagues ran a randomized crossover trial in 74 adults, published in JAMA Network Open in 2021, comparing sucralose against sucrose. Sucralose produced less suppression of acyl-ghrelin, the hunger hormone, and the neural responses in appetite and reward regions differed by sex and by BMI, with women and people with obesity looking most sensitive to the difference (5).

Most people do not want to be hungry. They want to lose weight, not gain it. If a drink is quietly making the day harder, that is a real cost even if nobody’s carotids are worse for it.

I will give you the trial that cuts against me, because it exists and it is better designed than most of what is in this post. Harrold and colleagues randomized 493 people in a 52-week behavioral weight-management program to either water or non-nutritively sweetened beverages. The sweetened-beverage group maintained more weight loss, 7.5 kg against 6.1 kg, a difference of 1.4 kg (6). That is a real randomized result and it says that for someone actively working a program, swapping to diet drinks did not sabotage them and may have helped.

So my position is not that diet soda is dangerous. It is that it is not good for you, the appetite signal is worth taking seriously in someone trying to lose weight, and if you are diabetic and choosing between two sodas, choose the one that does not move your glucose.

For patients

If you switched from regular soda to diet, do not switch back on the strength of these headlines. That trade still looks favorable.

If you are drinking several a day and trying to lose weight, cutting down is reasonable, and the best reason is appetite rather than any proven vascular danger. If you specifically avoid artificial sweeteners and use stevia or monk fruit blends, check the label for erythritol, because that is the one with the most concerning recent data.

For colleagues

The small artery occlusion subgroup in the WHI analysis is the finding worth knowing, because it is the one least explained by reverse causation.

Also worth knowing that patients hear “conditional recommendation on low-certainty evidence” as “WHO says diet soda is dangerous,” and correcting that is a two-sentence conversation that is usually worth having.

The Bottom Line

Daily diet soda has been linked to vascular events in several large cohorts, with hazard ratios in the 1.2 to 1.4 range, and the association survives adjustment. It has never been shown to cause them, and the people who choose diet soda are different from the people who do not in ways no adjustment fully captures. Diet soda beats regular soda. Water beats both. If you have diabetes and you are not giving up soda, take the one that does not move your glucose. If you are trying to lose weight, the argument against it is appetite rather than your arteries. And the most interesting recent finding is not about aspartame at all, it is about erythritol, which is in a great many products marketed to people who are trying to avoid artificial sweeteners.

Related Reading

How Do You Actually Lose Weight? A Doctor Explains

Newly Diagnosed With Type 2 Diabetes: What You Should Know

Doctor Supervised Weight Loss: What Works Long Term

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Sources

1. Gardener H, Rundek T, Markert M, et al. Diet soft drink consumption is associated with an increased risk of vascular events in the Northern Manhattan Study. J Gen Intern Med. 2012;27(9):1120-1126. PMID 22282311. https://pubmed.ncbi.nlm.nih.gov/22282311/

2. Mossavar-Rahmani Y, Kamensky V, Manson JE, et al. Artificially Sweetened Beverages and Stroke, Coronary Heart Disease, and All-Cause Mortality in the Women’s Health Initiative. Stroke. 2019;50(3):555-562. PMID 30802187. https://pubmed.ncbi.nlm.nih.gov/30802187/

3. Witkowski M, Nemet I, Alamri H, et al. The artificial sweetener erythritol and cardiovascular event risk. Nat Med. 2023;29(3):710-718. PMID 36849732. https://pubmed.ncbi.nlm.nih.gov/36849732/

4. World Health Organization. Use of non-sugar sweeteners: WHO guideline. 2023. https://www.who.int/publications/i/item/9789240073616

5. Yunker AG, Alves JM, Luo S, et al. Obesity and Sex-Related Associations With Differential Effects of Sucralose vs Sucrose on Appetite and Reward Processing: A Randomized Crossover Trial. JAMA Netw Open. 2021;4(9):e2126313. PMID 34581796. https://pubmed.ncbi.nlm.nih.gov/34581796/

6. Harrold JA, Hill S, Radu C, et al. Non-nutritive sweetened beverages versus water after a 52-week weight management programme: a randomised controlled trial. Int J Obes (Lond). 2024;48(1):83-93. PMID 37794246. https://pubmed.ncbi.nlm.nih.gov/37794246/

Remove all background people, empty room only

American Academy of Private Physicians Conference in Austin, TX

On By Dr. Scott RennieIn Healthcare System & TechnologyLeave a comment
This last weekend, I attended a summit by the  AAPP (American Academy of Private Physicians) in Austin, Texas.  The meeting provided great networking opportunities and information for physicians who are interested in starting their own private medical practice. We learned from a panel of physicians of various backgrounds about their private practices and some ways that they have made them successful.  It was encouraging to hear how the patients and physicians have found concierge/private practice to be restoring to the the doctor-patient relationship of past times – unbound by insurance companies and provider network constraints.

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Travel health kit with airplane tag still life

Pack a Carry-On First Aid Kit for Air Travel and Flying

On By Dr. Scott RennieIn Travel, Wilderness & Preparedness MedicineLeave a comment

Now that most airlines charge for checked bags, it makes sense to think about carrying your first aid kit with you on the plane. The right kit depends a lot on where you’re headed. A weekend trip to the beach looks very different from a year in the Peace Corps. Still, there are some basics worth considering.

Headaches, stomach upset, and minor aches are common on the road. Medications like ibuprofen or acetaminophen can help with headaches or muscle pain. For heartburn or indigestion, travelers often bring something familiar such as famotidine or omeprazole. If you’re prone to motion sickness, an over-the-counter option like dimenhydrinate can prevent a miserable flight or bus ride.

Blisters are another frequent problem. A few squares of moleskin or blister pads can keep you walking instead of limping. Sunscreen and insect repellent are also essentials, especially if you’re outdoors a lot. I usually suggest packing an antihistamine like diphenhydramine. It works for allergies, bug bites, and sometimes helps with sleep if you’re stuck in a noisy hotel room.

Bring your daily prescription medications in your carry-on. Bags get lost, and it’s not worth the risk. Keep pills in the original bottles with your name and pharmacy label. If you’re traveling with controlled substances, a letter from your doctor on letterhead is a smart idea. Some countries restrict narcotics, even if you have a prescription, so check local regulations before you fly.

Simple supplies round out a kit. Adhesive bandages in a few sizes, medical tape, and a small tube of antibiotic ointment cover most cuts and scrapes. Anti-itch creams are handy for mosquito bites. Pack hand wipes or sanitizer with at least 60 percent alcohol for times when running water isn’t available. If you wear glasses or contacts, bring an extra pair.

Travel sometimes means unique risks. At high altitude, acetazolamide may be prescribed to prevent sickness. In malaria regions, prophylaxis may be recommended. Water purification tablets are also helpful in areas where drinking water isn’t reliable. And it’s smart to carry a contact card with your emergency numbers, your healthcare provider’s information, and the location of nearby hospitals or clinics. Many travelers also write down the local U.S. embassy contact information.

Insurance is another detail that people often overlook. Before you leave, call your insurance company to see if your policy applies overseas. In some cases, buying a short-term travel policy provides coverage and peace of mind.

I once spoke with a couple who traveled to rural South America with nothing more than sunscreen and bandages. After the first week, one developed severe diarrhea, and they had no loperamide or oral rehydration solution. They ended up driving two hours to find a clinic. They told me later that if they had packed a simple kit with a few basic medications, the whole ordeal might have been avoided.

Travel is unpredictable. Having a small kit in your carry-on won’t solve every problem, but it gives you control in those first uncomfortable hours before you can reach care.

This is for general information only and not intended as medical advice for an individual patient. If you have questions about what to bring on your trip, talk with your healthcare provider.

Wishing you the best of health,

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Sources:

Build a First Aid Kit to Keep in Your Car for Travel

On By Dr. Scott RennieIn Travel, Wilderness & Preparedness MedicineLeave a comment

This is the second time I’ve revisited the idea of first aid kits for your car, and my view has shifted. At first, I thought having one small kit was enough. Now I think it’s better to keep two. I’ve found that having both a grab-and-go kit and a larger, more complete one is more practical, especially if you’re the first person to arrive at an accident.

The smaller kit is the one you carry quickly if you need to help right away. It doesn’t need to hold everything, just the essentials. A CPR mask, gloves, and some absorbent pads are a good start. Those pads don’t have to be fancy or sterile to be useful in an emergency. I’ve seen people improvise with feminine hygiene pads to stop bleeding. Add a pair of safety glasses to protect yourself and some glucose tablets in case someone with diabetes is crashing from low blood sugar. Keep it in something small like a mylar pouch so you can toss it in your hand and move fast.

The bigger kit is a different story. I think of it as a duplicate of a solid home first aid kit, but with extra gear for the road. When you’re traveling, you can’t always count on nearby supplies. I’ve noticed that once people put one together, they realize it’s far more complete than what most of their friends carry. That’s a good thing when you’re far from a store or waiting on emergency services.

The larger kit should handle more than just cuts and scrapes. Bandages, gauze, roller wraps, tape, and non-stick dressings are the basics. Add tools like scissors, tweezers, and splints. Medications such as ibuprofen, acetaminophen, diphenhydramine, and loperamide are worth keeping. If you vacuum seal your supplies, they stay dry and pack down smaller, which is useful in a car. I’ve seen this trick make a bulky kit fit under a seat without taking up space.

For heavier situations, I like including a tourniquet for severe bleeding, but it’s important to know how to use it safely so you don’t cut off circulation unnecessarily. Some people go further and keep suture material, forceps, or even an epinephrine pen if they have a known severe allergy. Not everyone needs that level of equipment, but if you have training, it can make sense.

Since this is for your car, a few extras stand out. A flashlight or headlamp, glow sticks, a Sharpie, and waterproof paper are all small but handy. Road flares, a fire extinguisher, or even a ham radio can turn your kit into something that’s useful beyond just medical problems. I’ve spoken with drivers who said they didn’t think much about this until they were stuck on a mountain pass in winter. They ended up using their emergency bivvy sack and glow sticks before the med supplies ever came out.

Having two kits may feel like overkill, but in practice, it makes sense. One is portable and fast. The other is comprehensive and ready for when the situation is bigger than you expected.

This article is for general information only and not medical advice for any individual. If you’re building a kit and have questions about what you should carry, talk with your medical provider.

Wishing you the best of health,

Scott Rennie, D.O.
Board Certified in Obesity Medicine and Family Medicine

This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.

Sources: