People take coenzyme Q10 (CoQ10) supplements for many reasons, including to boost energy, to speed recovery from exercise, and to help reduce the effects certain medicines can have on the heart, muscles, and other organs.

There is some evidence that coenzyme Q10 may help to:

• Reduce symptoms from taking statins, such as muscle pain, tenderness, weakness, cramping, or fatigue. ^{footnote 1}
• Stimulate the immune system.^{footnote 2}
• Protect the heart from being damaged from certain chemotherapy medicines.^{footnote 2}

Taking coenzyme Q10 (CoQ10) may cause mild insomnia, Opens dialog or a rise in liver enzymes in some people. Other reported side effects include rashes, nausea, upper abdominal pain, dizziness, sensitivity to light, irritability, headache, heartburn, and fatigue.

Taking CoQ10 can reduce the body's response to the blood thinner (anticoagulant) medicine warfarin.

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 breastfeeding.

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.