How it works: A twining vine common in southern China that has been used for hundreds of years to treat a variety of ailments like arthritis and skin diseases. Low doses have been shown to lower sperm density.
Why men might go for it: Side effects are well known, and do not include effects on libido, body weight, or hormones.
Why they might not: Traditionally prepared by simmering roots of the plant for an hour or more; a practical delivery method is in order but has not yet been developed.
Status: Undergoing studies, mostly in China.
Simple Heat Methods
How it works: Decades-old studies by a Swiss doctor practicing in India found that 21 consecutive days of 45-minute-long sitz baths at 116 degrees Fahrenheit provided six months of contraception.
Why men might go for it: Free and readily available.
Why they might not: A hot bath for the testes is not on every man's wish list; the method is time-consuming and requires considerable dedication.
Status: Available to anyone with a bathtub and a contract with the water company, but has yet to gain traction.
Myriad other contraceptive methods for males are in various stages of study or development. But, says Lissner, that research—and the dollars to fund it—can't come quickly enough. "Pharmaceutical companies have no incentive to develop a cheap long-lasting method, and we can't expect them to take the lead. Men will get one if, and only if, they demand it of their governments."