Over-the-counter pills, powders, extracts and tinctures can interact with other medications and cause unexpected side effects

Every time you head to the doctor’s office, it’s the same question: “What medications are you taking?” While you likely list all of your regular prescription medications, your over-the-counter medications and supplements matter, too. Your healthcare provider needs to know about anything you take regularly, including:

Here’s why it’s so important.

Potential interactions with medications

Just as prescription medications can interact with one another, so, too, can they interact with over-the-counter medications and supplements. Your healthcare provider needs a complete list of what you’re taking so they can be on the lookout for possible drug interactions, including when they write you a new prescription.

“Let’s say, for example, that you have an infection, and your doctor puts you on an antibiotic,” poses family medicine specialist Matthew Goldman, MD. “Calcium and iron supplements can bind to certain antibiotics, making it harder for your body to absorb them, which, ultimately, makes that medication less impactful on your infection.”

There are many other examples of how over-the-counter supplements can interact with prescription medications, like:

  • Vitamin K can prevent blood thinners from doing their job effectively.
  • Vitamins C and E can interfere with chemotherapy drugs.
  • If taken alongside an antidepressant, St. John’s wort can cause a life-threatening drug reaction called serotonin syndrome.

These are just a few of the many instances that drive home why your provider needs to know exactly what you take.

Underlying health conditions

“If you already have certain medical conditions, supplements can bring added risks,” Dr. Goldman warns. “Your provider needs to know what you take so they can make informed decisions about your care.”

Here are a few examples:

  • Blood clotting disorders. Many supplements interfere with blood clotting and raise your risk of bleeding. This makes them especially risky if you have a blood clotting disorder or an upcoming surgery.
  • Allergies.If you have plant allergies, herbal supplements like chamomile and echinacea may cause allergic reactions — even if you don’t realize you have allergies to those specific plants.
  • Pregnancy.Many vitamins and supplements are considered unsafe when you’re pregnant. For example, black cohosh may induce preterm labor, berberine may worsen jaundice in infants and large doses of vitamin A may lead to birth defects.

Dosage concerns

Too much of a good thing can be harmful. When you determine your own supplement dosage, you risk serious side effects and even overdosing.

For example:

Another problem? You might not even realize you’re taking too much.

“Sometimes, multivitamins and other combination supplements have overlapping ingredients,” Dr. Goldman explains, “so you may be getting more of one substance than you realize.”

There’s also the fact that the U.S. Food and Drug Administration (FDA) categorizes supplements as foods, not drugs. That means they aren’t regulated with the same standards as pharmaceutical medications, so you can’t always be sure the dosages are precise.

Importantly, dosage is mostly a supplement-specific problem. Dr. Goldman says you’re typically not at risk of vitamin overdoses from the foods you eat (though some exceptions exist). So, it’s always better to focus on diet than to add extra pills to the mix.

Other possible side effects

A lack of FDA regulation means supplement manufacturers don’t have to disclose possible side effects on their packaging. But just like medications, dietary supplements can bring unwanted side effects.

There are lots of examples, like the fact that oral aloe supplements can decrease potassium levels or that the active ingredient in licorice root can increase blood pressure.

“If you don’t tell your healthcare provider which supplements you take, they don’t have all the information they need to accurately troubleshoot any symptoms you’re experiencing,” Dr. Goldman reiterates.

What to do before your next visit

It may not seem like a big deal to add extra vitamins or herbal supplements to your daily medication regimen. But given the trouble that these over-the-counter options can sometimes cause, your healthcare provider needs to know exactly what you take, including:

  • The name of each medication or supplement
  • What it is and/or what it’s for (like a multivitamin, probiotic, vitamin D, etc.)
  • How much you take and how often you take it

Worried you’ll forget what you take or leave something off the list the next time you head into an appointment? Dr. Goldman shares a tip for staying thorough and organized.

“Bring your over-the-counter medications, supplements and vitamins with you to your appointment so your provider can see exactly what’s in them,” he recommends. “If you can’t do that, take pictures of the labels.”

Then, maintain an updated list of everything you take, whether it’s written on a piece of paper that you keep in your wallet or stored in an app on your phone. That way, when the doctor’s office asks you, “What medications are you taking?” you’ll be able to simply show them the list.