Not all doctors agree about the benefit of vitamins and supplements, but Dr. Kali Hollingsworth says there’s one thing we can all agree on: If you take any kind of vitamin or supplement, you need to tell your primary care doctor.

More than half of all American adults take some kind of vitamin, but most don’t think they need to tell their doctor. All vitamins, minerals, supplements, detox regimens—you name it—are medically important.

Unfortunately, just like prescription medications, the wrong combinations of vitamins can mean more harm than help. Some pre-existing health conditions don’t mix well with certain supplements. Some vitamins counteract or react with prescription medications—such as birth control, blood thinners, heart medication, and even antibiotics. Taking the wrong doses of vitamins, combining vitamins, or mixing supplements and alcohol could negatively affect your health.

Ask first

It’s always best to talk with your doctor before taking a supplement. Even more so if you already take medications, have health concerns, or are pregnant. People who take more than one medication or supplement are at high risk for a negative interaction. Some can take weeks to develop.

If you’re a caregiver who manages medications for a family member or a loved one, keep a list of every medication your loved one takes. This includes prescription and nonprescription drugs, nutritional supplements, and vitamins.

Be sure to have a doctor or a pharmacist review that list at least once a year to look for possible drug interactions.

Take extra care

Be aware of common supplements that can interact with medications. Here are just a few:

• St. John’s wort
• Feverfew
• Vitamin E
• Garlic
• Coenzyme Q10
• Fish oil
• Vitamin D

Millions of Americans are also taking probiotics for digestive health. There’s evidence that some probiotics may help prevent diarrhea caused by infections or antibiotics. Some may also ease the symptoms of irritable bowel syndrome or lactose intolerance. But the U.S. Food and Drug Administration hasn’t approved any health claims for probiotics.

“It’s always best to talk with your doctor before you start taking a supplement, especially if you already take medications, have health concerns, or are pregnant,” advises Dr. Hollingsworth.

People who take more than one medication or supplement are at high risk for a potentially negative interaction, some of which can take weeks to develop.

When possible, foods, not supplements, are the best sources of nutrients. That’s because produce is packed with other naturally occurring substances that are good for you, too.

If you’re a caregiver who manages medications for a family member or loved one, be sure to keep a list of every medication your loved one takes. This includes prescription and nonprescription drugs, as well as nutritional supplements and vitamins. Give a copy to each healthcare provider that your family member or loved one sees.

Be sure to have a doctor or pharmacist review that lists at least once a year and look for possible drug interactions.