8 Supplements You Should Never Mix with Medication

Did you know that more than 50 percent of American adults take dietary supplements? You might assume that all natural supplements are safe, however some contain ingredients that may be harmful when combined with medication.

Some supplements increase the effects of medication while others reduce them. Below are supplements you should never mix with medication.

1. St. John’s Wort and Cancer, Heart, and Kidney Medications

St. John’s wort interacts with so many medications. It speeds up the breakdown of meds, which prevents them from being properly absorbed.

In one case, this supplement almost took the life of a 74-year-old man who was taking prescription meds after a kidney transplant. St. John’s wort has also been shown to interfere with cancer treatment by speeding up the breakdown of certain chemotherapies.

That’s not all. St. John’s Wort also interacts with antidepressants, the blood thinner, warfarin, and other prescription medications.

2. Calcium and Bisphosphonates

Bisphosphonates are powerful and help increase bone density in osteoporosis patients. However, taking calcium supplements immediately after taking this med reduces its effectiveness.

Experts at the University of Washington recommend waiting for four hours before taking calcium.

3. Ginkgo Biloba and Warfarin

Ginkgo biloba is one of the most popular herbal remedies and a natural nootropic. It helps to improve blood circulation and contains antioxidants that fight inflammation. Warfarin, on the other hand, helps prevent blood clots. Taking ginkgo biloba increases its effect, which may lead to internal bleeding or stroke.

If you want to continue taking ginkgo biloba, talk to your doctor so they can recommend smaller doses of warfarin.

Other herbal remedies—like clove oil, alfalfa, danshen and horse chestnut—also interact with warfarin, according to Harvard Health.

4. Iron and Antibiotics

Iron supplements may help lower the risk of anemia, but they also reduce the absorption of antibiotics into the body.

Avoid taking iron supplements within two hours before or after taking antibiotics. Don’t forget to tell your doctors that you’re taking iron supplements when they prescribe antibiotics.

5. Fish Oil and Blood Pressure Meds

Whether you’re taking fish oil to improve brain function or fight inflammation, keep in mind that it interacts with blood pressure medications.

Fish oil increases the effect of blood pressure meds, which may lead to very low blood pressure levels.

6. Melatonin and Antidepressants

Melatonin may improve the quality of sleep, but it also reduces the effect of antidepressants. Combining melatonin with antidepressants may also cause too much sleepiness.

Before taking melatonin supplements, try these natural ways of boosting melatonin levels.

7. Zinc and Antibiotics

Zinc supplements reduce the amount of antibiotics your body absorbs. Luckily, you can avoid this interaction by taking the antibiotic four to six hours after taking the zinc supplement.

It’s worth noting that combining topical zinc ointment with antibiotic drugs, such as erythromycin, can help treat acne.

8. Vitamin C and Cancer Drugs

This may surprise you, but vitamin C and cancer drugs are not a good combination. According to WebMD, vitamin C reduces the effectiveness of many cancer drugs.

Researchers advise against taking vitamin C supplements when undergoing chemo. It’s safer to take multivitamins that contain vitamin C.

These are just some of the common supplements that interact with prescription medications. Any time you start a new medication, talk to your doctor or pharmacist about supplements you’re taking, so they can advise you about potential interactions.

Do you know other supplements that interact with meds?

Image via Thinkstock


Jack Y
Jack Y1 months ago


Jack Y
Jack Y1 months ago


Mia B
Melisa B3 months ago

thank you

Olivia M
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Louise R
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Thank you

Sharonaway R
Past Member 6 months ago

Thank you.

Peter Lee
Peter Lee6 months ago

Great Post. Thanks for sharing.


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