Background: Pyospermia is a multifactorial disease. There is no ideal treatment, but the most promising treatment modalities are antibiotics and antioxidants.

Objective: To evaluate the effects of coenzyme Q10 (CoQ10) on sperm motility of men with pyospermia treated with doxycycline.

Materials and Methods: The present study, a double-blinded, randomized, placebo-controlled trial, enrolled 84 men who attended Siriraj Infertility Clinic, Faculty of Medicine Siriraj Hospital, Mahidol University with pyospermia on the initial semen analysis (SA) (T0). The participants were randomly assigned into two groups, group A received oral doxycycline 100 mg twice daily for 14 days plus oral CoQ10 200 mg per day for 30 days and group B received the same dose of doxycycline plus placebo for 30 days. The SA was repeated at      30 ± 7 days (T1) and 60 ± 7 days (T2) after initiating treatment.

Results: Of 70 eligible participants, the age of the participants was around 36 years. None of them had symptomatic urethral infection or abnormal urological examination. There was no difference in body mass index, education level, and female infertility factors between groups (p > 0.05 for all). Two-thirds of both groups became non-pyospermic after the treatment. There was no difference of total sperm motility between group A and group B (46%; 32% to 55% versus 43%; 33% to 50% at T1 and 46%; 32% to 57% versus 45%; 32% to 53% at T2,   p > 0.05 for all).

Conclusion: A 30-day course of daily oral intake of 200 mg CoQ10 shows no additive benefit on total sperm motility in Thai men with pyospermia treated with doxycycline.