Does CoQ10 Have Side Effects?

Most adults can safely take CoQ10 (Coenzyme Q10) at doses up to 3,000 milligrams daily for up to 8 months, 1,200 milligrams for 16 months, or 600 milligrams for 30 months without any significant side effects reported.

However, some mild side effects have been reported, including: stomach discomfort, allergic rashes, loss of appetite, nausea, heartburn, vomiting, insomnia, fatigue, dizziness, light sensitivity, irritability, and diarrhea (especially at daily doses reaching 200 mg).