If you are currently being treated with any of the following medications, you should not use CoQ10 without first talking to your health care provider.

Daunorubicin and doxorubicin -- Coenzyme Q10 may help to reduce the toxic effects on the heart caused by daunorubicin (Cerubidin) and doxorubicin (Adriamycin), two chemotherapy medications that are commonly used to treat several kinds of cancer. Always speak to your oncologist before taking antioxidants along with chemotherapy.

Blood pressure medications -- In a clinical study of individuals taking blood pressure medications, including diltiazem (Cardizem), metoprolol (Lopressor or Toprol), enalapril (Vasotec), and nitroglycerin (Nitrostat or Nitrobid), CoQ10 supplementation allowed the individuals to take lower dosages of these drugs. This suggests that CoQ10 may enhance the effectiveness of certain blood pressure medications, but more research is needed to verify these results.

Blood-thinning medications -- There have been reports that coenzyme Q10 may decrease the effectiveness of blood-thinning medications such as warfarin (Coumadin) or clopidigrel (Plavix), leading to the need for increased doses. Therefore, given that this medication must be monitored very closely for maintenance of appropriate levels and steady blood thinning, CoQ10 should be used with warfarin only under careful supervision by your health care provider.

Timolol -- CoQ10 supplementation may reduce the heart-related side effects of timolol drops (Betoptic), a beta-blocker medication used to treat glaucoma, without decreasing the effectiveness of the medication.

Other -- Medications that can lower the levels of coenzyme Q10 in the body include statins for cholesterol , including atorvastatin (Lipitor), lovastatin (Mevacor), pravastatin (Pravachol, and simvastatin (Zocor), fibric acid derivatives for cholesterol, including gemfibrozil (Lopid), beta-blockers for high blood pressure, such as atenolol (Tenormin), labetolol (Normodyne), metoprolol (Lopressor or Toprol), and propranolol (Inderal), and tricyclic antidepressant medications, including amitriptyline (Elavil), doxepin (Sinequan), and imipramine (Tofranil).