Taking a daily multivitamin may seem like a simple way to support your health, but it can interfere with how certain medications work. Experts say vitamins and minerals can compete with medications for absorption in the body, potentially reducing the effectiveness of either one.
Common medications affected include thyroid drugs, blood thinners, certain antibiotics and osteoporosis treatments. For example, calcium and iron in multivitamins can block the absorption of thyroid medication, while vitamin K may interfere with blood thinners. Some antibiotics can also bind to minerals like magnesium and zinc, preventing the medication from reaching effective levels in the body.
Health experts say timing and consistency are key to avoiding these interactions. Separating doses by a few hours and keeping vitamin intake consistent can help reduce risks. Anyone taking prescription medications should review their supplement use with a healthcare provider to ensure their routine supports, rather than disrupts, their treatment.
SOURCE:
AOL, March 14, 2026