Clonidine is often used to reduce blood pressure as well as to counter symptoms that occur during withdrawal from alcohol and other addictive substances.
There is some evidence that clonidine might impair the body's ability to manufacture the substance coenzyme Q 10 (CoQ 10 ). 1 However, it has not yet been shown that CoQ 10 supplements offer any particular benefit to those taking this medication.
The herb Coleus forskohlii relaxes blood vessels and might have unpredictable effects if combined with clonidine.
References
REF1 Kishi H, et al. Bioenergetics in clinical medicine. III. Inhibition of coenzyme Q 10 -enzymes by clinically used anti-hypertensive drugs. Res Commun Chem Pathol Pharmacol 12(3): 533–540, 1975.
REF2 Brinker F. Herb contraindications and drug interactions, 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998: 140–141.