Dietary Supplements and Drug Interactions

Betty Chaffee/ July 15, 2020/ Dietary Supplements, Drug interactions, Medication safety/ 2 comments

Dietary supplements are popular among adults in the United States.  About 75% of us take at least one supplement, and many of us take several. Dietary supplements are a big money-maker, too, with over $30 billion in revenue in 2019. We take supplements for a variety of reasons, from doctors' recommendations to persuasive advertisements, and everything in between. We've talked in past articles about the looser regulations for supplements compared to medications, and why you need to choose products carefully. But it's also important to know that supplement labels aren't required to provide a list of warnings and precautions.

When you purchase an over-the-counter medication for a cold, mild pain, or other mild ailment, the label will have a list of things to watch out for. Possible drug interactions, concerns about underlying diseases, side effects to be aware of. You won't see any of those things on the label of the supplement you purchase. And that may give you the impression that there are no safety concerns. But don't be fooled! Dietary supplements ARE medications - they do affect how the body functions and may interact with other medications you take or underlying medical problems.

How can you choose a dietary supplement that's safe for you?

Pharmacists are often asked about the safety of dietary supplements, and we are more than happy to help you make choices that'll improve your health. But you can use information sources on your own, too, to learn more about supplements. With objective information about safety and effectiveness of supplements you can be prepared to purchase the right product. Of course, your pharmacist is ready to help if some questions remain unanswered!

The information sources listed below are available at no cost to you. They both contain information from established and unbiased sources. The databases used are the same ones used by medical professionals. The difference is that these sources are accessible to everyone. And the information is presented in a way that's easy to understand and apply to your individual situation.

Information about drug interactions with dietary supplements

My favorite source for drug interactions is from On this website you can actually enter every medication and supplement you take. When you submit the list for analysis, it will come back with an explanation of every potential interaction between your meds and supplements. Not only that, but it explains in a fair amount of detail the symptoms or problems you might encounter if the interaction occurs. It goes on to suggest whether you should avoid using the combination completely, or go ahead and use it and just watch for problems. 

A couple of pointers:

  • When you use this database you may also get a few possible interactions between your medications. Even medications you may have been taking together for some time. Don't panic! Many medications commonly used together have the potential to interact. Your doctor and pharmacist are likely already aware and may have decided the risk of a problem is very low. Or your doctor may be monitoring you closely for any sign of a problem. If you're concerned about a potential interaction between your medications, ask your pharmacist for more information.

  • You may find that a supplement you're wondering about isn't in the database. Most are, but there are some missing, commonly proprietary or combination products that are only available by the brand name. Take a look at the ingredients listed on the label - you may find that each individual ingredient can be entered into the database.

What about interactions with medical problems?

My favorite source for information about other aspects of safety is Here you can find most supplements listed alphabetically. All available research about a supplement is reviewed and summarized by pharmacists and physicians, and it's continually updated. It's unbiased and thorough. You can review what's known about interactions with underlying diseases, side effects and precautions, and efficacy.

Why is it so hard to get good information about supplements?

Don't be surprised if you find there's little conclusive research on the product you're investigating. That's pretty common with supplements. It's because manufacturers don't have to prove a supplement is effective for anything before putting it on the market. Often there's little research, and the research that's out there may not be well done. That's beginning to change, and more research is being done to learn about the health effects if dietary supplements. But at this point you may still find that some supplements have little objective information about efficacy and safety.

Don't forget about potency and purity!

Because dietary supplements aren't regulated by the government as closely as medications, there's no guarantee that a particular product contains the ingredients or amounts listed on the label. Learn more about how to assess potency and purity of a dietary supplement.

Make sure your dietary supplements are right for you!

Learn as much as you can about your supplement, then take the rest of your questions to your pharmacist!  Start a conversation in the comments below this article, or contact us directly at BetterMyMeds. We love hearing from you!



Share this Post

About Betty Chaffee

Betty Chaffee, PharmD, is owner and sole proprietor of BetterMyMeds, a Medication Management service devoted to helping people get the maximum benefit from their medications.


  1. I’ve been taking supplements for lots of years (Multi, C, and E). Any good?
    I don’t know, but I have felt your body gets use to it so I’ve always felt continue or if you change it do it slowly or if there is no perceivable problem continue.
    Good article!
    Have a great day, Carl W……

    1. Hi Carl, good to hear from you!

      Well, as far as whether multiple vitamins, vitamin C, and vitamin E are good, it depends on what you want to use them for. Typically multiple vitamins don’t do much for those who already eat a healthy, balanced diet. You know me, I’m all about trying to limit medicines and use healthful habits where possible. You can read my previous article on that here. If you look at the website I recommended in this week’s article, you’ll probably find that there’s scant evidence that vitamins C and E are beneficial for most things people take them for. But you’re right, people who take them without safety concerns, can afford them, and don’t mind taking more pills are probably just fine continuing if they want to.

Leave a Comment

Your email address will not be published. Required fields are marked *