It is essential to be aware of the potential interactions between vitamins and medications, as they can increase the risk of serious side effects. Certain dietary supplements can alter the absorption, metabolism, or excretion of a drug, potentially affecting its potency. For instance, fat-soluble vitamins (such as vitamin A, vitamin D, vitamin E, and vitamin K) can accumulate in the body over time and reach toxic levels. When warfarin and vitamin K-containing products are taken together, warfarin activity decreases and there is a decrease in prothrombin time and INR.
If the affected medication is to be taken chronically and the supplement is deemed necessary, the pharmacist should work with the patient and the prescriber to suggest alternatives that limit exposure to potentially dangerous drug interactions. In these cases, it may be necessary to interrupt or reduce the dosage of the multivitamin or increase the dose of phenytoin. Patients may not think to share information with their pharmacist about the vitamins and minerals they take, or they may think that the substances are harmless and irrelevant to their medication regimen. Let's look at some categories of medications to get a rough idea of some of the most common drug interactions.
Drug Interactions with VitaminsDr. Marilyn Tan, double certified in endocrinology and internal medicine and associate clinical professor of medicine at Stanford University School of Medicine, told Verywell that some supplements and vitamins can affect the absorption or metabolism of prescription drugs. Patients taking iron supplements or multivitamins containing iron should be told to avoid taking their supplement within two hours of receiving a dose of tetracycline or fluoroquinolone antibiotics, digoxin, or levothyroxine. It is important to remember that vitamins and supplements can also affect prescription medications when mixed.
Information on the use of vitamins, minerals, herbal products and other nutraceuticals should be documented in patient records for future reference. Ultimately, if you are taking medications, you should check with your doctor before adding vitamins and supplements. By being aware of potential interactions between vitamins and medications, you can help reduce your risk of serious side effects. It is important to consult with your doctor or pharmacist before taking any new supplements or medications.