What Happens When Men Take Hormonal Birth Control?
Caitlin Kinast couldn’t help feeling a bit salty during the 12 months her husband, Seth, was on birth control. “His energy was up through the roof,” she says. “He was super happy, like a teenager again.” She pauses. “I wish my birth control was like that.”
The Kinasts are sitting in a basement fertility lab at the University of Washington in Seattle, one of 15 sites around the world running the first real-life road test of a groundbreaking male contraceptive gel. We’ve barely exchanged pleasantries when Caitlin, 34, starts recounting the years of frustration that brought them here. She’d tried just about every kind of birth control—one prescription after another—but never found one that didn’t cause complications. Seth tried wearing condoms, but they irritated Caitlin’s skin. The couple already had one child and agreed they weren’t ready for a second. Yet it was always Caitlin’s body—and hers alone—that had to deal with the ramifications of trying to have sex while trying not to get pregnant.
Seth, also 34, felt powerless to help. He was nervous that a vasectomy might not be reversible, and wasn’t that the only option left to him? Then one day, on Reddit, he saw a post from a guy who claimed to be enrolled in a medical trial for something called NES/T. The drug, this person wrote, was an experimental form of male birth control—a super-goop that goes on the shoulders and suppresses sperm production. Yes, Seth thought.
And that’s how, in 2019, he and Caitlin found themselves in a volunteer pool with hundreds of other couples who would, over the course of a year, use NES/T as their only form of contraception. No condoms. No Pill. Just the gel. The NES/T study, a phase II clinical trial launched in 2018 and expected to reach its conclusion in 2023, is playing out in a time when other attempts to develop male contraceptives have stuttered or failed and in a political landscape that continues to strip away women’s reproductive freedoms and endanger the lives of pregnant people. In 2020, the Supreme Court ruled that employers can deny their workers birth-control coverage on the basis of religious or moral objections. A year later, birth-control access remained a seemingly low priority for lawmakers: Of the 199 state-level proposals to protect or expand access to contraceptive services, just 16 were passed. Meanwhile, 19 states enacted 108 abortion restrictions, making 2021 the grimmest year for abortion rights in half a century.
So, yeah, it’s fair to say that the need for male birth control, the very idea of which has often been treated as a futuristic joke, is, at this point, critical. And many in the scientific community—including the University of Washington site researchers who granted Cosmo special access to the trial and its participants—believe NES/T could be the answer.
Seth’s first hurdle: believing the stuff was legit. He’d read about previous attempts to develop a male contraceptive, including ones that required hormone injections given by a doctor, which somehow seemed more “real.” The NES/T gel, on the other hand, looked just like a hand sanitizer you’d grab at CVS. “It smells like Purell; it looks like Purell,” he says. “Can it really work if it’s just going on my skin?”
In theory, yes, says Diana Blithe, PhD, of the Contraceptive Development Program at the U.S. National Institutes of Health, which is funding the trial. Here’s how it works: Test subjects (men ages 18 to 50 who are in monogamous relationships with women ages 18 to 34) rub one pump of NES/T onto each shoulder every morning, after a shower. The couples agree to have otherwise unprotected sex once a month for a full year—bonus encounters encouraged—while researchers conduct regular semen and blood analyses to track NES/T’s effects. The gel is formulated to subdue sperm production by suppressing a man’s luteinizing and follicle-stimulating hormones, the crucial chemicals needed to make sperm. This comes courtesy of the branded progestin Nestorone (the “NES” in the gel’s name and a synthetic hormone that’s been used for years in a vaginal contraceptive ring and for endometriosis treatment).
“It drives these sperm producing hormones down to almost zero,” says John Amory, MD, a professor at the University of Washington and a co-investigator on the Seattle trial. It also all but eradicates testosterone production, which would be…er…counterproductive to sexual performance, so the drugmakers added in some testosterone—aka the “T”—to replace what gets lost.
While millions of women deal with it every day, reproductive hormone manipulation is a new frontier for most men. But Dev Bellman, a 29-year-old from Seattle who considers himself “kind of a feminist,” has always been curious about the possibility. He joined the NES/T trial in 2019. It all seemed low-risk enough, especially since any effects were meant to be reversible, and his partner of four years was totally on board. “She was like, ‘Hell yeah. Men should be taking more responsibility,’” he says. “It was really nice that I could step in and be like, ‘Let me meet you at your level and see what you’ve been going through.’”
Not that everyone in his life was so supportive. “I got the most pushback from family and people 35 and over,” he says. “Like, ‘Don’t do that. It’s scary. What if you become infertile? That’s just unnatural!’”
For Seth, NES/T came with an unexpected kick. His testosterone level had always been on the lower end of normal, so the T in his birth control actually resulted in a higher libido—“a lot more spontaneous erections,” he says, “kind of like being in high school again.”
“Any kind of physical endeavor…he had a little bit more endurance,” Caitlin laughs.
The application process presented some challenges though. The gel takes four hours to fully absorb, which means Seth’s bare shoulders couldn’t touch anyone else’s skin during that time. Worried it would rub off on his toddler son (and somehow cause the 2-year-old to sprout a 5-o’clock shadow), Seth sprinted to cover his delts every morning. At one point, the family took a vacation to Hawaii, and Seth had to bow out of morning excursions to the beach to keep his NES/T from sweating off or getting washed away in the surf. (Formulation and application tweaks may happen down the line.)
Plus, the whole thing never quite became a habit, even though Seth kept the bottle in plain sight next to his deodorant. One day, Caitlin had to rush his NES/T to his office because he had forgotten to apply. So he, like millions of birth-control-taking women before him, set a recurring alarm on his phone. “I definitely trusted that Seth was going to do this right,” Caitlin says. “But at the beginning, I was always asking, ‘Did you put your gel on?’ It’s just one of those things where it had been on me for almost 10 years. When I’m taking care of it, I know it’s okay.”
For what it’s worth—although not any less aggravating for women to hear about—NES/T may be more forgiving of user error than the Pill. A man’s sperm count doesn’t just bounce back to normal after a day or two of missed gel applications, so the chances of an unintended pregnancy seem low. Mike Bartley, 33, estimates that he missed a dose or so every month during his year in the NES/T trial. “I forgot for whatever reason,” he shrugs. “My sperm counts were always still zero.”
As other guys on NES/T will tell you, it’s not all blasé whoopses and high-school level horniness. Dev, a visibly fit guy as of last fall, spent the early weeks of his trial logging extra hours at the gym because the hormones added water weight to his frame. Not ideal but manageable, he says.
What did throw him was his heightened state of sensitivity. “I had these moments where I would just start crying,” he says. “I’d be really emotional and get way more upset about something that normally would be nothing.”
Still, he’s a fan. Being on NES/T helped set the stage, he says, for deeper empathy with his partner, who had struggled with unwanted mood effects from the Pill. “I never fully grasped what that was like,” he says. With his own emotions now running so high, he became better at communicating, a skill he’s worked to carry forward. “I learned to talk about my problems,” he explains. “I no longer bottle it up.”
But as gratifying as it may feel to have “increased emotional intelligence” as a side effect for a new men’s drug, Dev’s experience may not be the norm. Mike says his year on the gel was emotionally and physically uneventful. He signed up for the trial and…that was kind of it. Sure, he had some skin dryness on his shoulders, but he experienced none of the changes or challenges the others did. Sitting in his garage surrounded by camping gear, he now struggles to recall anything remarkable at all. Most days, he’d just apply the gel after his morning bike commute and workplace shower, then go about his day. “I didn’t really notice anything,” he says. The gel “was just kind of there.”
Once this NES/T study is over, the next step is a phase III clinical trial involving thousands of couples (and likely a pharmaceutical partner that believes in its commercial potential, Dr. Amory notes). Then, hopefully, eventually, FDA approval. The entire process could take another 10 years, but Blithe says the real-life feedback that’s been pouring in has immense value: “The response from men has been, ‘We wish we could continue to use it. When is it going to be available?’” she says. “And the women are saying, ‘I really don’t want to go back on my method. I liked it when he was taking it.’”
At the time of this writing, after more than three years of testing, exactly zero couples have gotten pregnant while using NES/T. The number might well change, but it is exciting. “We have had no serious adverse events—and I would say, overall, no big surprises,” says Stephanie Page, MD, PhD, a professor at the University of Washington School of Medicine and a lead investigator on the Seattle trial.
Dev would gladly go on the gel again if it were available in pharmacies, he says. The way he sees it, today’s younger couples are more open to confronting outmoded relationship norms, including those that revolve around contraception. “Even the way divorce looks now versus in earlier generations—people were staying in unhappy marriages, and now millennials, if they’re unhappy, they’ll up and leave,” he explains. “It’s the same with birth control. Who says it has to be this way forever? Why can’t we make it different?”
For now, post-NES/T, Mike’s sperm count has climbed back to normal. Same with Dev; he and his partner are currently using condoms and ovulation tracking as birth control. And Seth and Caitlin, who had a second child last year and are now debating having a third, wish they still had access to NES/T while they figure it out. Instead, Caitlin is back, once again, to bearing the contraceptive burden solo.
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