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Coenzyme Q10

Other common name(s): CoQ10, Co-Q10, CoQ-10, vitamin Q10

Scientific/medical name(s): ubiquinone, ubidecarenone


Coenzyme Q10 (CoQ10) is part of an enzyme complex that helps cells use sugar to generate chemical energy that the body can use to power its chemical reactions. Energy is needed for the cells to do their work, and each cell of the body can make CoQ10 on its own. There are a number of forms of coenzyme Q, but Q10 is the major form found in humans and animals, and it has been studied the most. CoQ10 can also be found in a number of foods, such as mackerel, salmon, sardines, beef, soybeans, peanuts, and spinach.


Some preliminary studies suggest that CoQ10 supplements may promote health and fight some diseases, but more research is needed. Some small studies have suggested that taking CoQ10 supplements may help reduce chemotherapy-related heart damage, but these results need to be confirmed by larger randomized clinical trials. CoQ10 may reduce the effectiveness of chemo and radiation therapy, so most oncologists would recommend avoiding it during cancer treatment.

How is it promoted for use?

CoQ10 is an antioxidant, a compound that blocks the actions of free radicals, activated oxygen molecules that can damage cells. Scientists also believe that CoQ10 may have an effect on the immune system.

CoQ10 is sometimes promoted as a treatment for cancer (most commonly breast cancer), often in combination with other vitamins. Supporters also claim CoQ10 supplements may protect the heart from the damaging effects of certain chemotherapy drugs, such as doxorubicin (Adriamycin).

Various web sites show that CoQ10 supplements are also promoted for heart disease, stroke, high blood pressure, muscular dystrophy, gum disease, chronic fatigue, Alzheimer’s Disease, AIDS, and other immune deficiencies. It’s touted to improve athletic performance and help people lose weight. Some claim that CoQ10 can reduce pain and weight loss in people with cancer. It’s also promoted to reduce the signs of aging when used in skin products.

What does it involve?

Coenzyme Q10 occurs naturally in the body. It can also be obtained from a number of foods or as a supplement. The usual supplement dose used in clinical studies is 90 to 400 milligrams per day. Supplements are available as tablets, capsules, and gelcaps. The pure compound is not absorbed well from the stomach and intestine. Formulas that also contain fat may be absorbed better into the body.

What is the history behind it?

Coenzyme Q10 was first identified in 1957. Particularly high amounts were found in heart tissue, which is why researchers became interested in the connection between CoQ10 and heart disease. Studies in the 1960s found a possible link between cancer (especially breast cancer) and lower levels of CoQ10 in the blood. However, CoQ10 levels naturally drop as people get older, which is also when people are more likely to get cancer. No normal range of CoQ10 in the blood has been defined.

Some laboratory studies suggested that CoQ10 might have a role as an immune system booster. Since then, researchers have been testing CoQ10 supplements for treating heart disease, cancer, and other conditions. Still, no firm conclusions have been reached about its usefulness in treating any disease.

What is the evidence?

Some laboratory and animal studies suggest that CoQ10 could theoretically have an effect on cancer. In addition to its ability to act as an antioxidant, CoQ10 has effects on cellular energy and on the immune system. Some laboratory and animal studies have supported this idea. However, evidence from human studies is still minimal.

People taking statin drugs for lowering blood cholesterol levels are noted to have low CoQ10 levels because the statin drugs interfere with mitochondrial function (CoQ10 is made in the cells’ mitochondria, where energy is produced for muscle movement). This was thought to be part of the cause for the painful muscles that some people get when they take statin drugs. However, a study looking at CoQ10 found that it did not help reduce painful muscles in people taking statins.

Early studies involving small numbers of patients have suggested certain CoQ10 supplements showed no harm. But the studies of CoQ10 for cancer done thus far have been fairly small and did not have rigorous designs, meaning that positive findings cannot be counted on without further research. Better-designed studies are needed with larger groups of patients to determine what effect, if any, it has on cancer.

In a Danish study, 32 women with breast cancer that had spread to the lymph nodes were treated with a nutritional supplement program of vitamins, minerals, essential fatty acids, and CoQ10, along with standard treatment. Six patients were reported to have some tumor shrinkage, and all survived at least 2 years. Because there was no comparison group in this study, it did not allow the effects of CoQ10 and the other supplements to be separated from those of the standard treatments. The study and a follow-up were published in 1994, and no studies on women with advanced breast cancer have been done since then to get better data.

In a Canadian study, 90 women with breast cancer that had not spread to distant organs were given high doses of different combinations of vitamins, minerals, and CoQ10 along with standard treatment. They were compared to 180 women not taking the supplements based on the type of conventional therapy received and by several breast cancer predictive factors such as patient age, how far the cancer had spread, and whether cancer cells contained estrogen receptors. Patients receiving only mainstream therapy tended to remain disease-free longer and live longer, although the difference was not quite statistically significant. One weak point of the study was that since the women received a combination of supplements, it was not possible to know how they might have responded to mainstream treatment plus CoQ10 alone.

One clinical trial looked at 142 male smokers randomly chosen to receive anti-oxidants including CoQ10 or a placebo for 2 months. The study found no difference in a chemical indicator of DNA damage, suggesting that CoQ10 is not likely to be useful in preventing cancer. However, no long-term clinical studies of CoQ10 and cancer occurrence have been published.

Low levels of CoQ10 have been linked to heart damage from chemotherapy treatment for cancer, especially from drugs called anthracyclines. A 2004 review looked at 6 clinical trials that tested the use of CoQ10 to protect the heart against damage from chemotherapy. The review noted that some of the studies were not well designed, but the results seemed to suggest that CoQ10 might provide some protection for the heart. The review concluded that further studies were needed to confirm the results.

No scientific research has been published in available medical journals concerning the possible effects of CoQ10 on pain, weight loss, or increased appetite.

Are there any possible problems or complications?

This product is sold as a dietary supplement in the United States. Unlike companies that produce drugs (which must be tested before being sold), the companies that make supplements are not required to prove to the Food and Drug Administration that their supplements are safe or effective, as long as they don't claim the supplements can prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or substance that is on the label, and some may include other substances (contaminants). Actual amounts per dose may vary between brands or even between different batches of the same brand. In 2007, the FDA wrote new rules to improve the quality of manufacturing for dietary supplements and the proper listing of supplement ingredients. But these rules do not address the safety of the ingredients or their effects on health.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.

Few serious reactions to CoQ10 have been reported. Side effects may include headache, heartburn, trouble sleeping, and fatigue. Very high doses may cause involuntary muscle movements. Some users report mild diarrhea and skin reactions. Little is known about dosage or consequences of long-term use of CoQ10 supplements. There have been reports that CoQ10 may interact with blood-thinning medications and could pose a risk for prolonged bleeding.

Because CoQ10 is a strong antioxidant, there are theoretical reasons to suspect that it might interfere with the effectiveness of chemotherapy and radiation therapy. At least one study showed that when mice with implanted human lung cancer were treated with radiation and given CoQ10, they had less slowdown in tumor growth than mice that were treated with radiation alone. This question has not been adequately studied in human clinical trials. CoQ did not affect the ability of doxorubicin (a chemotherapy drug) to kill breast cancer cells in laboratory dishes, but the effect of CoQ on chemotherapy in patients remains uncertain. Many oncologists would recommend avoiding CoQ10 and other antioxidant supplements during chemotherapy and radiation therapy, as well as for a few weeks before and after these treatments.

Relying on this type of treatment alone and avoiding or delaying conventional medical care for cancer may have serious health consequences.

To learn more

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-ACS-2345).

Dietary Supplements: What Is Safe?

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer


Bookstaver DA, Burkhalter NA, Hatzigeorgiou C. Effect of Coenzyme Q10 Supplementation on Statin-Induced Myalgias. Am J Cardiol. 2012 May 17.

Fetrow CW, Avila JR. Professional's Handbook of Complementary and Alternative Medicines. Springhouse, Pa: Springhouse Corp; 1999.

Folkers K, Brown R, Judy WV, Morita M. Survival of cancer patients on therapy with coenzyme Q10. Biochem Biophys Res Commun. 1993;192:241-245.

Greenlee H, Shaw J, Lau YK, Naini A, Maurer M. Lack of effect of coenzyme q10 on doxorubicin cytotoxicity in breast cancer cell cultures. Integr Cancer Ther. 2012; 11(3):243-250.

Hodges S, Hertz N, Lockwood K, Lister R. CoQ10: could it have a role in cancer management? Biofactors. 1999;9:365-370.

Lesperance ML, Olivotto IA, Forde N, et al. Mega-dose vitamins and minerals in the treatment of non-metastatic breast cancer: an historical cohort study. Breast Cancer Res Treat. 2002;76(2):137-143.

Lockwood K, Moesgaard S, Hanioka T, Folkers K. Apparent partial remission of breast cancer in 'high risk' patients supplemented with nutritional antioxidants, essential fatty acids and coenzyme Q10. Mol Aspects Med. 1994;15:S231-240.

Lund EL, Quistorff B, Spang-Thomsen M, Kristjansen PE. Effect of radiation therapy on small-cell lung cancer is reduced by ubiquinone intake. Folia Microbiol (Praha). 1998;43(5):505-506.

Memorial Sloan Kettering Cancer Center. Coenzyme Q10. Accessed at: http://www.mskcc.org/mskcc/html/69186.cfm on January 15, 2013.

National Cancer Institute Physician Data Query (PDQ). Coenzyme Q10. 2012. Accessed at: www.cancer.gov/cancertopics/pdq/cam/coenzymeQ10/healthprofessional on January 15, 2013.

Prieme H. Loft S. Nyyssönen K. Salonen JT. Poulsen HE. No effect of supplementation with vitamin E, ascorbic acid, or coenzyme Q10 on oxidative DNA damage estimated by 8-oxo-7,8-dihydro-2'-deoxyguanosine excretion in smokers. Amer J Clin Nutr. 1997; 65(2):503-7

Roffe L, Schmidt K, Ernst E. Efficacy of coenzyme Q10 for improved tolerability of cancer treatments: a systematic review. J Clin Oncol. 2004;;22(21):4418-4424.

Spigset O. Reduced effect of warfarin caused by ubide-carenone. Lancet. 1994;;344:1372-1373.

Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation

Last Medical Review: 01/15/2013
Last Revised: 01/15/2013