Many have heard of Vasalgel, a barrier method of male birth control. It's injected into the Vas Deferens, and blocks sperm from leaving the body. It is still experimental, it hasn't been reliably proven to be reversible, and it's expensive.

Men's Health is reporting on another possible method of male birth control, H2-gamendazole.

H2-gamendazole works by stepping in during the last stage of sperm development, before the little swimmers become full-fledged sperm. Sertoli cells help nourish the sperm up to this point by being literally tethered to them so that they can only swim away when they're developed.

H2-gamendazole steps in at this crucial stage, snipping away this tether before sperm can really become fully developed, which means the suckers are destined to die by the testes. If there’s no perfect sperm, there’s no way sperm can ever even make it to the ovary for conception, which means this very well might be an effective method of male contraception.

H2-gamendazole is in the animal trials stages, and there is no estimate given as to when it might be available.

There have been numerous tests done with H2-gamendazole: in one study, rats were given one oral dose of H2-gamendazole once a week, and within two weeks, they were sterile. But here's the kicker: H2-gamendazole is apparently reversible, because ten weeks after they were taken off their once-a-week dose, the rats were fertile again. Tash's team replicated this experiment with mice, rabbits, dogs, and monkeys, and for each animal, there was a "block in sperm production just exactly like we see in the rats," he told Science Magazine. Because it can be taken orally, the testes are especially responsive to it, which means that H2-gamendazole doesn't have a chance to mess around with other tissues and produce unwanted side effects.