Possible side effects of taking CoQ10 include nausea, vomiting and upset stomach, according to Mayo Clinic. Other side effects associated with CoQ10 include headache, decreased mobility, low blood pressure and blood sugar level fluctuations. It can also cause itching and rashes on the skin. CoQ10 may affect thyroid hormone levels and interact with thyroid agents.
CoQ10 may affect a person's heart rate, increase the risk of bleeding and affect liver enzyme levels, notes Mayo Clinic. Other potential side effects of CoQ10 include viral infection, urinary infection, stomach pain and trembling. Some people may experience a sore throat or runny nose after taking CoQ10. CoQ10 can cause sinus inflammation, a respiratory tract infection, night sweats and reduced g-force tolerance.
Other possible side effects of CoQ10 include back pain, abnormal breathing, changes in attention and bronchitis, states Mayo Clinic. CoQ10 can cause changes in sperm motility, and it may also cause dizziness, falling, fainting and chest pain. After taking CoQ10, some people may have gas or diarrhea.
Experiencing symptoms similar to the flu sometimes occurs after taking CoQ10, according to Mayo Clinic. It can also cause pressure in the head, hearing loss, a fungal skin infection and increased light sensitivity. Indigestion and heartburn are possible side effects of CoQ10. It can also cause a heart attack or heart dysfunction.
CoQ10 is likely safe when healthy people take it for up to eight months in doses of 3,000 milligrams or less per day, states Mayo Clinic. People should use it cautiously when taking high doses for an extended period of time.