If you’re too busy to eat a well-balanced diet, you’d likely benefit from taking a good multivitamin every day. Multivitamins offer an inexpensive way to supplement your daily nutritional needs. Vitamin-drug interactions Ask your pharmacist or healthcare provider about potential interactions between multivitamins and any medications that you’re taking. It may be best not to take them at the same time of day, for instance. The reason: When you mix certain medications and multivitamins, they can interact to hinder each other’s use in your body, so they don't work as intended. An example: Minerals such as iron, calcium, and magnesium can interact with the thyroid medication levothyroxine (Synthroid, Levoxyl, Levothroid) and the antibiotics ciprofloxacin (Cipro) and tetracycline (Sumycin), hindering their effectiveness. To be safe, take your multivitamin at least two hours before or after taking any of these medications. Deficiencies Without supplementation, a few prescription medications may even lead to vitamin or mineral deficiencies. For example, orlistat (Xenical), a new prescription drug for obesity, can block your stomach’s absorption of vitamins A, D, E, and K. That’s why doctors and pharmacists recommend a daily multivitamin supplement with these vitamins for all Xenical users. Be sure to take the multivitamin at least two hours before or after taking Xenical, for instance at bedtime. Birth control pills may lower levels of >vitamin B6 (pyridoxine), resulting in mood changes. That’s why some experts recommend that birth control pill users with mood changes take a vitamin B6 supplement, though this is controversial. Isoniazid (INH), a prescription drug for tuberculosis, can also cause a deficiency in vitamin B6, which in turn may lead to a nerve condition called neuropathy. That’s why doctors and pharmacists recommend a vitamin B6 supplement for people on INH whose diabetes, alcoholism, or malnutrition raises their risk of neuropathy. Bottom line Look for a multivitamin that provides 100 percent of the daily values for both vitamins and essential minerals. (But it isn't possible to fit the full daily value of all minerals such as calcium into a single multivitamin. So you need to try to get your calcium by eating and drinking such foods as dairy products, or take a separate calcium supplement.) Again, check with your pharmacist or healthcare provider about potential multivitamin-drug interactions. Sources:
Hansten, P.D., J.R. Horn. Drug Interactions Analysis and Management. Applied Therapeutics, 2000.
Micromedex Healthcare Series. Micromedex, Inc., 2000.
Drug Facts and Comparisons, Facts and Comparisons, 2000.
Silverman, H.M., J.A. Romano, G. Elmer. The Vitamin Book. Bantam Books, 1999.
This answer prepared 7/25/00.
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