Dietary supplements and herbal products
How supplements are regulated, why «natural» does not mean safe, and the interactions and hidden ingredients to watch for.
Vitamins, minerals, herbal products and other supplements are widely used and often bought without professional advice. They are regulated differently from medicines: in the United States, and in a comparable way in Colombia, they do not go through the same efficacy review before sale. Some interact with prescription drugs, and some products contain undeclared medicines.
How regulation differs
Under the US Dietary Supplement Health and Education Act of 1994, companies evaluate the safety and labelling of their own supplements before selling them; the FDA does not approve them first and acts after marketing when a product is adulterated or misbranded. Labels can make structure/function claims but cannot claim to treat a disease. In Colombia, Decreto 3249 de 2006 sets the rules for manufacturing, sanitary registration, quality control, labelling and surveillance of dietary supplements, and INVIMA oversees them.
Quality problems
- The amount of active ingredient can differ from the label or between batches.
- Contamination with heavy metals, microbes or the wrong plant species.
- Hidden prescription drugs: for example, a banned weight-loss drug (sibutramine) in a product sold as all-natural, or undeclared drugs in sexual enhancement products.
- «Herbal» or «natural» on the label does not mean safe.
Interactions
St John's wort is the best-known example. It speeds up the metabolism of many drugs and can make them fail: oral contraceptives, cyclosporine in transplant patients, warfarin, some antiseizure drugs, digoxin, some HIV drugs, several cancer drugs and some statins. Combined with antidepressants or other serotonergic drugs it can cause serotonin-related reactions. Other supplements, such as garlic, may add to bleeding risk in people taking anticoagulants.
What professionals do
Ask about supplements and herbal products in every history, especially before surgery, in pregnancy, in older adults and with drugs that have a narrow therapeutic index. Suspected reactions to supplements are reported to the regulator, as for medicines: in Colombia through INVIMA, in the US through the FDA.
Test yourself
Think of the answer, then tap the question to see it.
Does the FDA approve dietary supplements for safety and efficacy before they are sold?
No. Manufacturers are responsible for safety and labelling; the FDA acts after marketing against adulterated or misbranded products.
Which Colombian rule governs dietary supplements, and which agency oversees them?
Decreto 3249 de 2006, with INVIMA in charge of registration, quality control and surveillance.
Why can St John's wort make an oral contraceptive fail?
It speeds the metabolism of many drugs, lowering their levels and effect.
Which kinds of supplements are most often found to contain hidden drugs?
Products sold for sexual enhancement, weight loss, bodybuilding, pain or sleep.
Example drugs
Connections
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Dietary Supplements (U.S. Food and Drug Administration, 2026); Avoiding Products Contaminated with Hidden Ingredients (U.S. Food and Drug Administration, 2026); St. John's Wort: Usefulness and Safety (National Center for Complementary and Integrative Health (NCCIH), NIH, 2026); Decreto 3249 de 2006: Regulación de suplementos dietarios en Colombia (Instituto Nacional de Vigilancia de Medicamentos y Alimentos (INVIMA), Colombia, 2006).
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Representative model, for educational purposes only.