Our top picks for emerging methods

Which male contraceptives could be ready first? Which ones are the most promising? Here are our top picks:

RISUG/Vasalgel

What it is: A polymer gel that goes in the vas deferens and kills sperm for more than 10 years. In animal tests, it’s been reliably reversible.
Why we like it: It’s ultra-targeted and specific—no hormone side effects throughout the body. Like vasectomy, it’s “get it and forget it”—one 10-minute procedure and then nothing to think about after that. But unlike vasectomy, it looks like it will be reversible—a huge difference, since psychologically, most people like to keep their options open, and men who aren’t finished having children could use it too.
The holdup and next steps: RISUG is in advanced clinical trials in India and could be available on a limited basis there in the next few years if problems with the syringe design have been solved. In the U.S., a nonprofit foundation is taking up the project under the name “Vasalgel” and doing everything to FDA standards—now all that’s needed is additional funders and investors for the $5 million social venture project.
Show your support: tell us your story so we can show big funders all the reasons men and women want RISUG. And sign up to donate, invest, or hear when clinical trials start.

What it is: Fifteen minutes of painless treatment to the testes provides six months of contraception.
Why we like it: It’s targeted (testes-only), so there are no unpredictable side effects like with hormones. And it’s done using machines that are already in physical therapists’ offices all over the world. Multiple treatments one after another a few days apart can even be used for permanent sterilization.
The catch/next steps: Researchers at the University of North Carolina have confirmed the original researcher’s results, getting an effect in rats—but it took a lot of adjusting to get it right. Armed with those results, they were able to win a small Gates Foundation grant to study it further. Researchers in Italy are successfully using ultrasound to sterilize male dogs. But researchers at the University of California haven’t been able to get it to work in monkeys. What’s the missing secret? We need to figure out before ultrasound use can be widespread.

Tripterygium wilfordii

What they are: Extracts from plants traditionally known to have contraceptive effect. The most advanced work is on plants from India, China, and Indonesia.
Why we like it: This would satisfy people who want a short-term method—and we already know it works.
The catch: To make enough to satisfy the world’s men, you can’t just gather plants—you have to identify the active compound and then chemically synthesize it, which requires very specific skills. Researchers on the Indonesian pill (Justicia gendarussa) have already done this, but researchers on the Indian and Chinese compounds (carica papaya and TW) haven’t. Then you need to test it extensively, since plant compounds can have effects throughout the body (for example, the Indonesian plant seems to have effects similar to aspirin, and the Chinese compound, Tripterygium wilfordii, is used in higher doses to treat autoimmune disease). Finally, reversibility studies need to go on long term before an oral drug can be considered reversible rather than just a vasectomy alternative. This will require a concerted, coordinated effort, preferably at a center funded specifically to test and compare compounds. And that means money!

What they are: The testes need to be slightly cooler than the rest of the body to properly produce sperm. If you keep them at body temperature during the day (with an underwear modification to keep them tucked in the inguinal canal), or a lot warmer for a shorter period of time (with testes-only baths for 45 minutes a day for 3 weeks every 6 months), contraception can be available for free.
Why we like it: It’s simple, free, and available right now to anybody.
The catch/next steps: It takes dedication. And though there are lots of small studies that show it works, the low-tech nature and “eww, weird” factor has kept funders from supporting the large studies that would be reassuring. If you’d like to see these studies done, make your voice heard.