Figuring out a safe, effective form of male contraception has been a tough nut to crack (so to speak). It requires stopping not one egg from doing its job, but millions of backstroking sperm. But researchers are now pretty damn close to making that happen, if a recent study in the Journal of Clinical Endocrinology and Metabolism is to be believed.

Researchers gave 320 men at health centers around the world injections of testosterone (to trick the brain into stopping production) and progestin (a derivative of female hormones that tells the brain to stop making sperm), every eight weeks for 24 weeks. Results were stellar: The injections were 96% effective, with only four pregnancies among the subjects’ partners, though, 20 men did drop out because they couldn’t handle the side effects of the injections, like acne, pain, palpitations, erectile dysfunction, depression, and other mood disorders. Guess PMS isn’t such a joke when you’re the one sobbing.