Introduction: There is unmet need for male contraceptive options, but a recent injectable combination male contraceptive trial was terminated early due to adverse events (AEs).

Methods: We examined the frequency of reported AEs by male research participants compared with AEs reported in prescribing information of approved female hormonal contraceptive methods. Published data from trials of the top five most-used female hormonal contraceptives, supplemented by contemporary contraceptive research, were compared with the frequency of AEs reported in a male injectable hormonal contraceptive trial.

Results: We observed similar frequencies of AEs reported by users of male contraceptives compared with those reported by female users. Among quantitatively comparable AEs, compared with men, women reported experiencing higher frequencies of headaches, pelvic pain, and weight gain and similar frequencies of decreased libido. Compared with women, men reported experiencing higher frequencies of acne and mood changes. Men discontinued participation due to AEs at a lower frequency than women.

Conclusions: Female hormonal methods generally have similar frequencies of AEs to those reported in a recent male hormonal contraceptive trial, and male users had lower rates of discontinuation due to AEs. There were fewer serious AEs of the male contraceptive than reported in contemporary female trials which resulted in FDA licensure. This suggests there may be implicit bias in the scientific community regarding the level of acceptable risk for users of male contraceptive methods.

Competing interests: None declared.

• HHSN275201300025I/HD/NICHD NIH HHS/United States
• K23 HD071788/HD/NICHD NIH HHS/United States
• U54 HD012629/HD/NICHD NIH HHS/United States
• P30 AI027757/AI/NIAID NIH HHS/United States
• U54 HD042454/HD/NICHD NIH HHS/United States