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Heart Failure Health Center

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Coenzyme Q10 - Topic Overview

Other claims

Research does not support a helpful effect of CoQ10 in periodontal (gum) disease, muscular dystrophy, or exercise recovery.

Is CoQ10 safe?

Taking 100 mg a day or more of CoQ10 has caused mild insomnia in some people. And research has detected elevated levels of liver enzymes in people taking doses of 300 mg per day for long periods of time. Liver toxicity has not been reported.

Other reported side effects include rashes, nausea, upper abdominal pain, dizziness, sensitivity to light, irritability, headache, heartburn, and fatigue.

Medicines for high cholesterol (statins) and medicines that lower blood sugar cause a decrease of CoQ10 levels and reduce the effects of CoQ10 supplements. CoQ10 can reduce the body's response to the blood thinner (anticoagulant) medicine warfarin (Coumadin) and can decrease insulin requirements in people with diabetes.

The U.S. Food and Drug Administration (FDA) does not regulate dietary supplements in the same way it regulates medicines. A dietary supplement can be sold with limited or no research on how well it works or on its safety.

Always tell your doctor if you are using a dietary supplement or if you are thinking about combining a dietary supplement with your conventional medical treatment. It may not be safe to forgo your conventional medical treatment and rely only on a dietary supplement. This is especially important for women who are pregnant or breast-feeding.

When using dietary supplements, keep in mind the following:

  • Like conventional medicines, dietary supplements may cause side effects, trigger allergic reactions, or interact with prescription and nonprescription medicines or other supplements you might be taking. A side effect or interaction with another medicine or supplement may make other health conditions worse. Always tell your doctor or pharmacist about all dietary supplements you are taking.
  • The way dietary supplements are manufactured may not be standardized. Because of this, how well they work or any side effects they cause may differ among brands or even within different lots of the same brand. The form of supplement that you buy in health food or grocery stores may not be the same as the form used in research.
  • Other than for vitamins and minerals, the long-term effects of most dietary supplements are not known.

WebMD Medical Reference from Healthwise

Last Updated: November 14, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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