Are vitamins supplements safe

You probably check the interactions between your medications, but did you know you should do the same with supplements? Taking multiple drugs and/or supplements can increase your risk for side effects and adverse interactions, including cognitive impairment and delirium. Even herbal supplements from natural sources can have potent active ingredients and dangerous interactions with drugs, other supplements, and certain foods and beverages.

Several online resources allow you to check interactions between drugs and supplements you are taking. Most analyze drug-drug interactions. Information on drug-supplement, drug-food, or supplement-supplement interactions is also available on several sites, though it is less thorough.

The Drug Interactions tool allows you to check for drug-drug interactions as well as drug-food, and drug-disease state interactions. It has the most complete drug-drug information of the sites we examined, with a rating of the interaction severity. You can also find limited information on vitamins and some common herbs and supplements. (Uncommon supplements such as rhodiola and ashwagandha are not included.) With the tool, you can also analyze multiple drugs, supplements, and herbs at the same time.

Medscape's Drug Interaction Checker allows you to check for drug-drug, drug-supplement, and supplement-supplement interactions. The checker includes vitamins, common herbs and supplements, as well as some uncommon ones. This tool also lets you analyze multiple drugs, supplements, and herbs at once. Some interactions detected by were missed by and the information on supplement interactions is incomplete.

Memorial Sloan Kettering Cancer Center

This site provides detailed information for over 200 herbs, including many uncommon supplements and those often used by cancer patients. While it does not offer an interaction checker, the site provides interaction information for each herb in the "Potential Interactions" section by clicking on "Herb-Drug Interactions." In some cases, the list of drug interactions is incomplete.

The Rxisk Interaction Checker uses two resources provided by the US National Library of Medicine:

  • ONCHigh: a list of high-priority drug-drug interactions derived by a panel of experts
  • DrugBank: a database of drugs and drug-drug interactions

At Rxisk, you can check multiple drugs and supplements at once. However, only common supplements and vitamins are in the system and the supplement interaction information is incomplete. Some interactions detected by were missed by

The Rxlist Drug Interaction Checker includes drug-drug interactions as well as some vitamins. This tool allows you to check multiple drugs at once. However, it also failed to find some drug-drug interactions detected by

The WebMD Interaction Checker analyzes drugs, vitamins, and some herbs and supplements. And you can check multiple drugs and vitamins at once. The information, however, is incomplete for drug-drug, drug-supplement, and supplement-supplement interactions.


These online resources can be helpful in avoiding the most common interaction issues, but may miss problems with less common supplements or herbs. To be safe, ask your physician or pharmacist about possible side effects and interactions. Have a list ready with all medications and supplements you are taking along with dosages. It is also a good idea to fill all prescription medications at a single pharmacy.

Yuko Hara, PhD, is Director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation. Dr. Hara was previously an Assistant Professor in Neuroscience at the Icahn School of Medicine at Mount Sinai, where she remains an adjunct faculty member. Her research focused on brain aging, specifically how estrogens and reproductive aging influence the aging brain's synapses and mitochondria. She earned a doctorate in neurology and neuroscience at Weill Graduate School of Medical Sciences of Cornell University and a bachelor's degree in biology from Cornell University, with additional study at Keio University in Japan. Dr. Hara has authored numerous peer-reviewed publications, including articles in PNAS and Journal of Neuroscience.

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