The clipboard says “List all medications.” You write down the blood pressure pill and the thyroid tablet. You do not write down the turmeric, the fish oil, the magnesium you take for cramps, or the St. John’s wort a coworker swore by.
Most people don’t. The form said medications, and in your head those are not medications. They came from a grocery store aisle, not a pharmacy counter.
That gap is enormous. A February 2021 federal data brief from the National Center for Health Statistics, part of the CDC, reported that 57.6% of US adults aged 20 and over had taken at least one dietary supplement in the previous 30 days. Among women 60 and older it was 80.2%. Nearly one adult in seven, 13.8%, was taking four or more products at once, and among adults 60 and over that figure hit 24.9%.
So the clipboard is wrong far more often than it is right. Here is what the silence costs, and how to end it in about ninety seconds of your next visit.
How many people are taking what, and how many say so
The CDC figures come from the National Health and Nutrition Examination Survey, which interviews and examines a nationally representative sample rather than relying on a mailing list. For 2017 to 2018, the breakdown ran 63.8% of women and 50.8% of men. Use climbed steadily with age in both sexes. Multivitamin-mineral blends led the list, with vitamin D and omega-3 products close behind. Across a decade, age-adjusted use rose from 48.4% in 2007 to 2008 up to 56.1% in 2017 to 2018.
Measuring how many of those people tell their doctors is harder, and the US research is thinner than it should be. A 2016 research letter in JAMA Internal Medicine by Judy Jou and Pamela Jo Johnson examined nondisclosure of complementary and alternative medicine use to primary care physicians using the 2012 National Health Interview Survey. A 2019 cross-sectional study in JAMA Oncology by Nina Sanford and colleagues did the same for American cancer patients and survivors. Neither study’s published abstract carries its figures, so this article does not quote a figure from either one. What both establish is that nondisclosure is common enough in the United States to be worth studying in two different patient populations.
One smaller US study does give usable numbers. A 2023 cross-sectional survey published in Gerontology and Geriatric Medicine, led by Julia Golden at UConn Health, asked 173 adults aged 65 and older about their use of complementary approaches. Sixty percent reported using at least one in the past year. Of those users, 64.4% had told their primary care practitioner, which leaves about a third who hadn’t. Disclosure rates varied by what people were using: 71.9% told their clinician about supplements and herbal products, but only 48% mentioned body work such as massage. The one factor that predicted disclosure was trust in the clinician, with an odds ratio of 2.97.
That is a single survey of 173 people at one institution, so treat it as a sketch rather than a national estimate. The direction it points, though, matches the rest of the literature.
Why people stay quiet
The best study of the reasons is not American, and that matters, so it gets labeled plainly here. A 2024 mixed-methods paper in BMC Complementary Medicine and Therapies, led by Pauliina Aarva at Tampere University, drew on an online survey of 6,802 complementary therapy users in Finland. Its findings describe why Finnish patients keep quiet. They are not a measurement of US behavior.
The reasons are recognizable anyway. The researchers identified three distinct kinds of silence. One was avoidant: people bracing for a dismissive or disapproving reaction and heading it off by saying nothing. One was precautionary: people who had already been brushed off once and were not going to repeat the experience. The third was conditional: people who felt perfectly confident and simply decided case by case whether a given doctor needed to know. The paper also names three common reasons found across this literature: expecting an unaccepting response, never being asked, and believing the information isn’t necessary.
Add a fourth belief that shows up constantly in American exam rooms: the idea that a plant or a vitamin is not a drug, so it doesn’t belong on the medication list. That belief is the costly one, because it is wrong at the level of basic chemistry. A compound that has an effect on your body has an effect on your body regardless of which aisle it came from. Many of our most important medicines started as plants.
The regulatory gap that makes your list matter
Here is the mechanism most people never learn, and it changes how you should think about this whole conversation.
Prescription and over-the-counter drugs go through FDA review before they can be sold. Dietary supplements do not. The FDA’s own consumer page states that “The FDA does NOT have the authority to approve dietary supplements for safety and effectiveness.”
The National Institutes of Health Office of Dietary Supplements, in a consumer fact sheet last updated January 4, 2023, lays out the rest. Supplement companies are responsible for holding evidence that their products are safe and for labeling them truthfully. But unless a product contains a new dietary ingredient, defined as one introduced after October 15, 1994, the company does not have to hand that safety evidence to the FDA before putting the product on shelves.
That date is the hinge. Ingredients already in commerce on October 15, 1994 were effectively grandfathered in. Manufacturers must follow Good Manufacturing Practices, the FDA can act against unsafe products and request recalls, and the Federal Trade Commission polices advertising claims. All of that is after-the-fact enforcement.
Why this matters in the exam room: your clinician’s prescribing software carries an enormous, actively maintained database of drug-drug interactions. There is no equivalent registry telling her what you bought. If you don’t say it, nobody knows it, and no system will catch it for you.
The interactions that land people in trouble
Not every combination is dangerous. Some are, and the evidence on those is solid rather than theoretical.
The NIH Office of Dietary Supplements names two in plain language. On blood thinners, the fact sheet states that “Vitamin K can reduce the ability of the blood thinner warfarin to prevent blood from clotting.” And St. John’s wort, it says, speeds up the breakdown of many medicines and makes them less effective, including antidepressants, birth control pills, heart medications, HIV drugs and transplant medications.
St. John’s wort is the textbook case, and the history is specific. A 2020 review in the British Journal of Pharmacology by Simon Nicolussi and colleagues traces the problem to around 2000, when a pharmacokinetic interaction between St. John’s wort and cyclosporine was linked to acute rejection in two heart transplant patients. The mechanism is now well mapped: the herb activates a receptor that ramps up the liver enzymes and transport proteins responsible for clearing drugs out of the body, so blood levels of those drugs drop. A 2009 systematic review in Drugs by Angelo Izzo and Edzard Ernst examined seven widely used herbal products and found 128 case reports or case series plus 80 clinical trials, with St. John’s wort accounting for the longest list of affected medicines.
The National Center for Complementary and Integrative Health adds several that are less famous. Concentrated green tea supplements can lower blood levels of atorvastatin, a cholesterol drug, and nadolol, a beta blocker. Goldenseal appears to change how the body handles a range of drugs including the diabetes medicine metformin. For Asian ginseng, NCCIH describes uncertainty rather than established harm around blood pressure medicines, statins and some antidepressants.
That last distinction is the honest one. For a great many supplement and medicine pairs, nobody knows, because the studies have not been done. NCCIH says so directly. If your doctor tells you she isn’t sure, that is frequently an accurate statement about the state of the evidence rather than a brush-off.
NCCIH also flags the category where the stakes are highest: drugs with a narrow therapeutic index, meaning the gap between a dose that works and a dose that causes harm is small. Digoxin, cyclosporine and warfarin are the examples it names. If you take any of them, a supplement change is not a minor detail.
Surgery is the sharpest moment
The Office of Dietary Supplements is specific here. Some supplements raise bleeding risk, and some taken before an operation can change how you respond to anesthesia. The FDA makes the same point about dangerous effects during surgery.
This is the one deadline in the whole article. Bring your supplement list to the pre-op visit, not the morning of. Your surgeon or anesthesiologist may want certain products stopped a week or two ahead, and that decision cannot be made at 6 a.m. in a pre-operative bay.
What to bring, and how to open the conversation
The Office of Dietary Supplements recommends keeping a complete written record and offers a printable form whose columns are the product name, the dose, how often you take it, and why you take it. That last column is the one clinicians find most useful and patients most often leave blank.
Here is a fuller version you can keep as a note on your phone. For each product, record:
- The exact product name as printed on the label, not the general category. “Turmeric curcumin 500 mg capsules, Brand X” tells a pharmacist far more than “turmeric.”
- The dose and how often. Include whether you take it with food.
- Why you take it. One phrase. “For joint stiffness.” “My sister said it helps with sleep.”
- When you started. New products are the ones most likely to explain a new symptom.
- Who suggested it. A clinician, a friend, an ad, a store employee. This tells your doctor whether anyone with training has looked at it.
- Whether you’d notice if you stopped. This is the question that separates products worth defending from products worth dropping.
Easier still: put the bottles in a bag and bring them, or photograph every label, front and back, and bring your phone. The National Center for Complementary and Integrative Health advises listing everything you use on the patient history form and bringing an updated list to each visit rather than only the first one.
For the opening line, lead with the fact rather than an apology. “Before we go further, I want to show you everything I take that isn’t a prescription.” It takes four seconds, it signals that you consider this medical information, and it prevents the conversation from starting defensively.
Your pharmacist is the most underused person in this
Pharmacists spend their training on exactly this problem, they are reachable without an appointment, and they are free to talk to.
The Office of Dietary Supplements explicitly includes pharmacists, along with dentists and dietitians, among the providers who should know what you take. The federal Agency for Healthcare Research and Quality, in its patient brochure, tells people to check with a doctor or pharmacist before stopping any prescribed medicine.
Walk your list to the counter and ask one question: “Does anything here interact with my prescriptions?” A pharmacist can run your full list, prescription and non-prescription together, against an interaction database in a couple of minutes. If you fill prescriptions at more than one pharmacy, bring the list to whichever one has the longest record of you, and consider consolidating.
The honest limit applies here too. A pharmacist can tell you about documented interactions. For a supplement with no published interaction data, the accurate answer is that nobody knows, and a good pharmacist will say that rather than invent reassurance.
If your clinician brushes it off
It happens. The useful response is to narrow, not to retreat.
A broad opening like “what do you think about turmeric?” invites a shrug. A narrow one is harder to wave away: “I take 500 mg of this twice a day. Does it interact with anything on my list?” That is a concrete question with a findable answer, and most clinicians will either answer it or look it up.
If the answer is a flat dismissal with no reasoning, you still have options short of changing doctors. Send the list through the patient portal so it lands in your chart in writing. Ask the pharmacist. Raise it again at the next visit, because the Golden study’s one significant finding was that trust predicted disclosure, and trust accumulates across visits rather than appearing in one.
What you should not do is stop telling them. The nondisclosure is the dangerous part, not the disagreement.
When this becomes urgent rather than a conversation
Some situations need attention sooner than your next scheduled visit.
Call your clinician promptly if you are on a blood thinner and notice unusual bruising, bleeding gums, nosebleeds that won’t stop, or blood in your stool or urine. Call if your skin or the whites of your eyes look yellow, if your urine turns dark, or if you have persistent nausea and pain in the upper right side of your abdomen, since those can signal liver injury. NCCIH names comfrey and kava as natural products that have caused serious liver damage, a direct correction to the belief that natural means harmless.
Call before you start anything new if you take a transplant medication, an HIV antiretroviral, a seizure medicine, a thyroid medicine, a heart rhythm drug, or warfarin. Call if you have surgery scheduled and nobody has reviewed your supplements yet.
And be particularly careful with products marketed for weight loss, sexual improvement, or bodybuilding and athletic performance. NCCIH reports that products in exactly those categories have been found to contain hidden prescription drugs and other undisclosed compounds. In those cases the label is not a reliable account of what you are swallowing, which means your doctor cannot assess it even if you do disclose.
The one thing to do before your next appointment
Open your medicine cabinet tonight and photograph every supplement label you own, front and back, with your phone. Put the photos in one album.
That is the entire task. It takes three minutes, it survives the fact that you will forget the name of the magnesium, and it converts a conversation you have been avoiding into one you can start by handing someone your phone.
The goal is not to defend what you take or to be talked out of it. It is to make sure the person adjusting your prescriptions is working from a complete list instead of a partial one.
Sources
- National Center for Health Statistics, Centers for Disease Control and Prevention. “Dietary Supplement Use Among Adults: United States, 2017-2018 (NCHS Data Brief No. 399).” cdc.gov
- National Institutes of Health Office of Dietary Supplements. “Dietary Supplements: What You Need to Know.” ods.od.nih.gov
- U.S. Food and Drug Administration. “FDA 101: Dietary Supplements.” fda.gov
- U.S. Food and Drug Administration. “Dietary Supplements.”
- National Center for Complementary and Integrative Health. “4 Tips: Start Talking With Your Health Care Providers About Complementary Health Approaches.” nccih.nih.gov
- National Center for Complementary and Integrative Health. “6 Tips: How Herbs Can Interact With Medicines.” nccih.nih.gov
- National Center for Complementary and Integrative Health. “5 Tips: What Consumers Need To Know About Dietary Supplements.” nccih.nih.gov
- Agency for Healthcare Research and Quality. “Be More Engaged in Your Healthcare.” ahrq.gov
- MedlinePlus, National Library of Medicine. “Talking With Your Doctor.” medlineplus.gov
- Jou J, Johnson PJ, JAMA Internal Medicine, 2016. PubMed. DOI: 10.1001/jamainternmed.2015.8593. “Nondisclosure of Complementary and Alternative Medicine Use to Primary Care Physicians: Findings From the 2012 National Health Interview Survey.” doi.org
- Sanford NN et al., JAMA Oncology, 2019. PubMed. DOI: 10.1001/jamaoncol.2019.0349. “Prevalence and Nondisclosure of Complementary and Alternative Medicine Use in Patients With Cancer and Cancer Survivors in the United States.” doi.org
- Golden J et al., Gerontology & Geriatric Medicine, 2023. PubMed. DOI: 10.1177/23337214231179839. “Disclosure of Complementary and Alternative Medicine Use Among Older Adults: A Cross-Sectional Study.” doi.org
- Aarva P et al., BMC Complementary Medicine and Therapies, 2024. PubMed. DOI: 10.1186/s12906-024-04640-w. “Varieties of silence: a mixed-methods study exploring reasons and justifications for nondisclosure of the use of complementary therapies to physicians in Finland.” doi.org
- Nicolussi S et al., British Journal of Pharmacology, 2020. PubMed. DOI: 10.1111/bph.14936. “Clinical relevance of St. John's wort drug interactions revisited.” doi.org
- Izzo AA, Ernst E, Drugs, 2009. PubMed. DOI: 10.2165/11317010-000000000-00000. “Interactions between herbal medicines and prescribed drugs: an updated systematic review.” doi.org