That’s a big “if,” and it hinges on a tangle of scientific, social, and bureaucratic complications. The gel itself is more than a decade in the making, developed by researchers at the Los Angeles Biomedical Research Institute and the University of Washington. The groups have spent their careers chasing better birth control options for men, but none has made it onto pharmacy shelves yet. But the gel—called NES/T—looks very promising. Now the researchers just need to study how it works with Medrano and the other couples in the wild, hoping to prove that hormonal male birth control finally deserves to move out of the lab and into men’s lives.

Recently, some 400 other couples in nine cities worldwide have similarly worked the gel into their daily routines. It is one of the largest investigations into hormonal male contraception ever. Like Medrano, they’ll use the gel in place of other contraceptives while researchers monitor their sperm counts and any unforeseen side effects. If the gel makes it to market, it will become the first hormonal contraceptive for men—more than a half-century after the first birth control pill was approved for women.

A few years ago, Julia stopped taking Depo-Provera, an injectable form of hormonal birth control, which had caused her weight to fluctuate and made her, in Medrano’s words, “kind of moody.” Condoms worked fine, but Julia worried about slipping up. So when Medrano came across a post on Reddit recruiting participants for a clinical trial of this new kind of male contraceptive , it seemed worth a shot. Julia, happy to be relieved of the burden of managing the couple’s birth control, agreed.

The gel, which Medrano describes as having the consistency of hand sanitizer, contains testosterone and progestin, a hormonal composite that suppress his body’s natural production of sperm. Massaged into his skin, it functions as the only birth control he and his wife, Julia, will use for the next year and a half.

The path to hormonal male contraception begins in 1957, in the laboratory of Gregory Pincus, an endocrinologist who made his name studying the effects of hormones on ailments like heart disease and schizophrenia. In 1951, encouraged by a friendship from the feminist activist Margaret Sanger—and a small grant from the Planned Parenthood Federation of America—Pincus began researching how hormones could manipulate a woman’s menstrual cycle and forestall ovulation. A combination of estrogen and progestin, he found, did the trick. His invention, called Envoid, was marketed as a “menstrual regulator with a side effect of preventing pregnancy.” In 1960, the FDA approved its use as a contraceptive, which would soon become known simply as “the pill.”

While doing the research that led to the pill, Pincus also hoped to create an analog of the drug for men. It seemed that, just as progestin could upset a woman’s natural cycle, it could also disrupt the natural production of sperm. He and other researchers put this hypothesis to the test in the late ’50s, injecting both men and women in Massachusetts mental hospitals with doses of the drug (ethical standards were looser at the time) to see if it could render men temporarily sterile. The results were inconclusive.

Arielle Pardes covers personal technology, social media, and culture for WIRED.

“As soon as this began, the women who were funding the project—[Margaret] Sanger and [birth-control pioneer Katharine] McCormick, became furious. They just wanted it for women,” says Jonathan Eig, the author of The Birth of the Pill. “It’s brilliant design if what you’re trying to do is put control into the hands of women. But over time, one of the side effects is that men are not even participating in the conversation.”

Interest in male birth control waned, eclipsed by the overwhelming success of the pill. But some researchers continued to work on the idea in the next few decades. The National Institutes of Health supported clinical trials throughout the 1970s, followed by multinational studies sponsored by the World Health Organization in the 1990s. In China, researchers experimented with gossypol, a plant derivative, to lower sperm count nonhormonally. Another plant extract, ouabain, has also been considered. (The compound is used by African hunters, who dip their arrows in it to stop the hearts of their prey.) In India, scientists have found promise with an injection-based procedure called RISUG, sometimes called a “nonsurgical vasectomy.” None of these methods has made it to market.

Stephanie Page had just finished her medical training when, in 2002, she began researching male hormonal birth control. Now a professor at the University of Washington School of Medicine, Page oversees three studies of new contraceptive methods for men: a hormonal pill, which suppresses sperm production with a compound called DMU; an injection, modeled after the Depo-Provera shot for women; and the NES/T gel, which uses a type of progestin called nesterone in concert with testosterone. Of the three, the gel is the furthest along, though Page cautions that “drug development is not a startup. It doesn’t happen overnight, or even in a matter of years.”

Progestin has been proven, in many trials, to stunt sperm production. The testosterone is in there to balance out its side effects, like loss of libido, hair loss, or fatigue. Christina Chung-Lun Wang, a researcher at Los Angeles Biomed and another principal investigator in the NES/T clinical trials, says similar methods of male birth control have been tested as far back as the 1970s, with “overwhelmingly very positive” results. “So the goal now is to find a combination that will be just as efficacious but with minimal side effects,” she says.

Developing contraception for men is basically a numbers game, involving very large numbers. A woman’s fertility is cyclical; the target, a single ovulation. For men, sperm production is continuous; the targets are legion. “In one ejaculate, there are millions of sperm—15 to 200 million per milliliter,” Page says. But fertility researchers have learned that a man’s sperm count doesn’t need to be lowered to zero—a count of around 1 million sperm per milliliter of ejaculate is low enough to count as contraception. (Statistically, none of those 1 million sperm will reach the egg.) The combination of testosterone and progestin can accomplish that reduction. It’s reversible too; when men stop taking it, their sperm counts should bounce back. The greater challenge is getting pharmaceutical companies interested enough to fund R&D and in getting men to take such a drug.

Men simply haven’t had to push for a future where more birth control options exist. And it’s not clear whether men would take a birth control pill: Some surveys show that men are reluctant, while others suggest the opposite. The most pervasive feeling might be apathy—a sense of complacency because women are running the contraceptive show. “There’s no real buy-in when it comes to men taking responsibility for birth control,” says Eig of Birth of the Pill. Plus, “the pill becomes so successful financially that there’s not much incentive for researchers to investigate new forms of birth control for men either.”

Wang says there is “zero industry interest” from pharmaceutical firms to fund new methods of contraception that target men. To develop the NES/T gel, she and Page have relied on funding from the National Institute of Child Health and Human Development and the Population Council, a nonprofit that supports biomedical research. Other nonprofits, like the Bill and Melinda Gates Foundation, have also earmarked funds for research on male contraception. These groups are focused on finding new ways to meet contraceptive needs; in the US, almost half of pregnancies are unplanned. That signals the need for better and more diverse options.

“The goal is not to take away what’s already accepted, but to provide another avenue, another choice,” according to Wang.

In Los Angeles, Medrano makes occasional visits to see Wang to have his sperm levels checked, to monitor the effects of the NES/T gel. So far, everything seems to be working as planned—Julia is not pregnant. Recently, he says he thinks the hormones are making him “a little bit moody,” which has made him more sympathetic what Julia experienced with Depo-Provera.

When he tells his friends about the gel and taking part in a clinical trial, some of them seem surprised. Birth control for men? They’d never heard of such a thing. But then, Medrano says, the excited questions start rolling in. “They all wanted to know what the side effects were,” he adds, “and when they could get it.”

How We Reproduce