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Cancer Health Center

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Coenzyme Q10 (PDQ®): Complementary and alternative medicine - Health Professional Information [NCI] - Adverse Effects

No serious toxicity associated with the use of coenzyme Q10 has been reported.[1,2,3,4]Doses of 100 mg /day or higher have caused mild insomnia in some individuals. Liver enzyme elevation has been detected in patients taking doses of 300 mg/day for extended periods of time, but no liver toxicity has been reported.[1] Researchers in one cardiovascular study reported that coenzyme Q10 caused rashes, nausea, and epigastric (upper abdominal) pain that required withdrawal of a small number of patients from the study.[5] Other reported side effects have included dizziness, photophobia (abnormal visual sensitivity to light), irritability,[5] headache, heartburn, and fatigue.[6]

Certain lipid -lowering drugs, such as the statins (lovastatin, pravastatin, and simvastatin) and gemfibrozil, as well as oral agents that lower blood sugar, such as glyburide and tolazamide, cause a decrease in serum levels of coenzyme Q10 and reduce the effects of coenzyme Q10 supplementation.[1,7,8,9] Beta-blockers (drugs that slow the heart rate and lower blood pressure) can inhibit coenzyme Q10 -dependent enzyme reactions. The contractile force of the heart in patients with high blood pressure can be increased by coenzyme Q10 administration.[1] Coenzyme Q10 can reduce the body's response to the anticoagulant drug warfarin.[9] Finally, coenzyme Q10 can decrease insulin requirements in individuals with diabetes.

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  1. Pepping J: Coenzyme Q10. Am J Health Syst Pharm 56 (6): 519-21, 1999.
  2. Overvad K, Diamant B, Holm L, et al.: Coenzyme Q10 in health and disease. Eur J Clin Nutr 53 (10): 764-70, 1999.
  3. Hodges S, Hertz N, Lockwood K, et al.: CoQ10: could it have a role in cancer management? Biofactors 9 (2-4): 365-70, 1999.
  4. Heller JH: Disease, the host defense, and Q-10. Perspect Biol Med 16 (2): 181-7, 1973 Winter.
  5. Baggio E, Gandini R, Plancher AC, et al.: Italian multicenter study on the safety and efficacy of coenzyme Q10 as adjunctive therapy in heart failure. CoQ10 Drug Surveillance Investigators. Mol Aspects Med 15 (Suppl): s287-94, 1994.
  6. Feigin A, Kieburtz K, Como P, et al.: Assessment of coenzyme Q10 tolerability in Huntington's disease. Mov Disord 11 (3): 321-3, 1996.
  7. Kaikkonen J, Nyyssönen K, Tuomainen TP, et al.: Determinants of plasma coenzyme Q10 in humans. FEBS Lett 443 (2): 163-6, 1999.
  8. Thibault A, Samid D, Tompkins AC, et al.: Phase I study of lovastatin, an inhibitor of the mevalonate pathway, in patients with cancer. Clin Cancer Res 2 (3): 483-91, 1996.
  9. Coenzyme Q10. In: Jellin JM, Hitchens K, eds.: Natural Medicines Comprehensive Database. Stockton, Calif: Therapeutic Research Faculty, 1999, pp 241-42.

    This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

    WebMD Public Information from the National Cancer Institute

    Last Updated: 8/, 015
    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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