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 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 Natural and Non-Prescription Health Products Directorate (NNHPD), within the Health Products and Food Branch of Health Canada, regulates natural health products in Canada. Natural health products, including CoQ10, must be reviewed and approved by the NNHPD before they can be sold in Canada.

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

When using natural health products, keep in mind the following:

• Like conventional medicines, natural health products may cause side effects, trigger allergic reactions, or interact with prescription and non-prescription medicines or other natural health products you might be taking. A side effect or interaction with another medicine or natural health product may make other health conditions worse. Always tell your doctor or pharmacist about all natural health products you are taking.
• The way natural health products 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 natural health product 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 natural health products are not known.