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

Daunorubicin and Doxorubicin
Coenzyme Q10 may help to reduce the toxic effects on the heart caused by daunorubicin and doxorubicin, two chemotherapy medications that are commonly used to treat a variety of cancers.

Blood Pressure Medications
In a study of individuals taking blood pressure medications (including diltiazem, metoprolol, enalapril, and nitrate), 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.

Warfarin
There have been reports that coenzyme Q10 may decrease the effectiveness of blood-thinning medications such as warfarin, 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 only be used with warfarin under careful supervision by your healthcare provider.

Timolol
CoQ10 supplementation may reduce the heart-related side effects of timolol drops, 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 (atorvastatin, cerivastatin, lovastatin, pravastatin, simvastatin), fibric acid derivatives for cholesterol (specifically, gemfibrozil), beta-blockers for high blood pressure (such as atenolol, labetolol, metoprolol, and propranolol), and tricyclic antidepressant medications (including amitriptyline, amoxapine, clomipramine, desipramine, doxepin, imipramine, nortriptyline, protriptyline, and trimipramine).