Federal health agencies are urging adults over 65 to bring every bottle, capsule, and herbal product to their next pharmacy visit, and the reason is measurable: common supplements can change how prescription drugs behave in the body. CDC surveillance data show that dietary supplement use rises steadily with age, meaning the population most likely to take multiple prescription medications is also the population most likely to add unregulated products on top of them. An NIH-funded study found that goldenseal extract lowered metformin levels by roughly 25 percent in healthy adults, a shift large enough to undermine blood sugar control in someone managing diabetes. The gap between what older patients take and what their providers know about creates a safety problem that no federal database currently tracks in full.
Why pharmacist reviews matter more after 65
Aging changes the body’s ability to break down and clear both drugs and supplements. The liver slows its metabolic work, kidneys filter less efficiently, and body composition shifts in ways that alter how long active compounds stay in circulation. The FDA’s advice for older adults spells out the consequence: when someone over 65 takes several prescription medicines alongside over-the-counter drugs and dietary supplements, the risk of harmful interactions rises sharply. The agency explicitly recommends telling a pharmacist about all products in use so that duplication and interaction risks can be caught before they cause harm.
That recommendation carries extra weight because of how supplements reach the market. Under the Dietary Supplement Health and Education Act of 1994, classified as Public Law 103-417, supplements are regulated differently from prescription drugs. Manufacturers do not need to prove safety or effectiveness before selling a product. The FDA can act only after a problem surfaces, relying on post-market adverse event reports submitted through its Safety Reporting Portal. That reactive system means a pharmacist’s review during a routine visit is often the first and only checkpoint where a dangerous combination gets flagged.
The hypothesis that linking state prescription drug monitoring programs with voluntary supplement-use reporting could surface high-risk herb-drug pairs remains untested. No published analysis has matched NHANES 30-day supplement files to concurrent prescription records for adults 65 and older to quantify actual co-use interaction pairs. State pharmacy boards have not published data on whether medication therapy management programs for seniors require supplement review. The result is a blind spot: the people at greatest risk are the least visible in existing surveillance.
Goldenseal, green tea, and the drugs they disrupt
The NIH’s National Center for Complementary and Integrative Health has documented specific interactions that illustrate the scale of the problem. An NCCIH-funded study found that goldenseal extract reduced metformin blood levels by approximately 25 percent in healthy volunteers, according to the agency’s clinical digest for health professionals. Metformin is one of the most widely prescribed diabetes drugs in the United States, and a 25 percent drop in its effective concentration could leave blood sugar dangerously uncontrolled in an older patient who has no idea the supplement is interfering.
Concentrated green tea supplements present a separate risk. NCCIH consumer guidance notes that these products can alter drug levels in the body, a concern for anyone taking medications with a narrow therapeutic index such as warfarin or digoxin. For those drugs, even small shifts in blood concentration can trigger serious bleeding or cardiac events. The NCCIH tips on herb–drug interactions emphasize that seemingly mild products, including teas and capsules sold as “natural,” can change how the liver’s enzymes process prescription medicines.
The NIH’s aging specialists echo that warning. The National Institute on Aging cautions that supplements can produce unwanted side effects and unsafe interactions with prescription medications, and advises older adults to have a doctor or pharmacist review every product they use. That guidance applies not only to herbal concentrates but also to high-dose vitamins, minerals, and combination formulas marketed for joint health, memory, or “immune support.”
A peer-reviewed analysis published in JAMA Network Open documented another dimension of the problem. Researchers examined the FDA’s list of tainted products marketed as dietary supplements and found unapproved pharmaceutical ingredients hidden in products sold for sexual enhancement, weight loss, and sports performance. For an older adult already taking blood pressure or heart medications, swallowing a supplement that secretly contains an active pharmaceutical ingredient adds a layer of risk that no label discloses. In such cases, even a careful pharmacist review can be undermined because the ingredient profile the pharmacist sees is incomplete.
Gaps in tracking supplement risks for older patients
Several pieces of the safety picture are still missing. The CDC’s National Center for Health Statistics collected 30-day dietary supplement use data through the NHANES survey cycle covering 2017 through 2018, and its Data Brief No. 561 confirmed that supplement use climbs with age. But the FDA’s adverse event reporting system does not publish age-stratified counts for supplement-related hospitalizations tied specifically to herb-drug interactions. Without that breakdown, researchers and regulators cannot measure how often the interactions documented in clinical studies translate into real emergency department visits among seniors.
Pharmacist medication-reconciliation logs, which would show how often older adults voluntarily disclose supplement use during routine reviews, have not been aggregated in any national dataset. That absence makes it impossible to know whether the FDA’s advice to “tell your pharmacist” is being followed at a rate that actually prevents harm. The NHANES microdata infrastructure exists to support original analysis of prescription and supplement co-use, but publicly available files stop short of linking specific herb-drug combinations to clinical outcomes such as hypoglycemia, arrhythmias, or bleeding events.
Electronic health records add only partial clarity. Many systems allow clinicians to enter nonprescription products into a medication list, yet completion depends on patients remembering every pill they take and clinicians having time to ask. Older adults may not think of a multivitamin, a probiotic, or an herbal sleep aid as “medicine,” and therefore omit it when asked about current drugs. Without systematic prompts and standardized fields, those omissions translate into undercounted exposure in research datasets and missed interaction warnings at the point of care.
State-level monitoring tools are similarly limited. Prescription drug monitoring programs track controlled substances such as opioids and benzodiazepines but do not capture nonprescription supplement purchases. Pharmacy benefit managers may see claims for over-the-counter products when they are billed through insurance, yet many supplements are bought with cash at retail chains, online marketplaces, or specialty shops. That fragmented purchasing landscape makes it difficult to construct a complete picture of what older patients are actually taking.
Researchers have proposed several remedies, from adding structured supplement fields to national surveys and hospital discharge records to piloting pharmacist-led reconciliation programs that explicitly include herbs and vitamins. Any of these approaches would require sustained funding and coordination among federal agencies, state boards, and professional associations. For now, the most immediate safeguard remains simple and low-tech: older adults gathering every bottle they use and asking a pharmacist or clinician to look for problems.
That conversation cannot eliminate all risk, especially when products contain undisclosed ingredients, but it can catch known interactions like goldenseal with metformin or concentrated green tea with cardiac medicines before they escalate. It can also prompt difficult but necessary questions about whether a supplement is providing any benefit at all. Until surveillance systems fully reflect what older Americans are swallowing alongside their prescriptions, the safest assumption for patients and providers alike is that every pill matters, and none should be taken in isolation from the rest.
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*This article was researched with the help of AI, with human editors creating the final content.
