Coenzyme Q10 Side Effects
Although studies have shown that side effects of coenzyme Q10 (if they even occur) are not likely to be serious, you should contact your healthcare provider right away if you develop fainting, allergic reactions, or signs of liver damage. These serious side effects may indicate that you should stop taking the supplements. Other, less serious coenzyme Q10 side effects may include nausea, diarrhea, and loss of appetite.
Coenzyme Q10 (CoQ10) is a vitamin-like substance produced by the human body. Just because coenzyme Q10 is a naturally occurring human compound, however, does not automatically mean that it is free of side effects. For most people, side effects, if they occur, are merely bothersome. In fact, most people tolerate coenzyme Q10 supplements quite well, often with no side effects or just mild ones.
(This article covers many, but not all, of the possible side effects with coenzyme Q10. Your healthcare provider can discuss a more complete list of coenzyme Q10 side effects with you.)
In general, studies have shown that coenzyme Q10 supplements are not likely to cause serious side effects. However, based on reported side effects or theoretical problems that could occur, there are a number of side effects with coenzyme Q10 that you should report to your healthcare provider. These side effects may also indicate that you should stop taking the supplement. These include but are not limited to:
- Dizziness or fainting, which could be a sign of low blood pressure
- High liver enzymes (early studies suggested that coenzyme Q10 could increase liver enzymes, although later studies have not confirmed this)
- Signs of an allergic reaction, including an unexplained rash, hives, itching, unexplained swelling, wheezing, or difficulty breathing or swallowing.
Coenzyme Q10 supplements are regulated as dietary supplements, not as medications. Because dietary supplements are not as closely regulated as medications, they may be more likely to contain contaminants or have more or less of the active ingredient than stated on the label. As a result, it is reasonable to predict that some poor-quality coenzyme Q10 supplements could cause side effects due to contaminants or other manufacturing defects. This is why it is important to choose high-quality supplements from reputable manufacturers.