Scientists at the University of Minnesota created a contraceptive pill that was proven to be 99% effective at preventing pregnancy in mice. According to Md Abdullah Al Noman, a Ph.D. candidate and one of the project’s main researchers, human trials could begin “as early as the end of this year.”

The new pill targets interactions with Vitamin A, key to sperm production and fertility. Mice that took the pill were functionally sterile after four weeks. Those same mice returned to normal levels of virility four to six weeks after treatments ended.

Even though they still need approval from the U.S. Food and Drug Administration in order to begin human trials, a number of men have already volunteered to participate, according to Gunda Georg, a medical chemistry professor at the university who led the research. 

“The response to our findings has been overwhelming. Men care a lot about this topic,” Georg told Fortune. “The volunteers show that there is interest and there’s willingness on the part of men to participate and to take the contraceptive.”

To market in 5 years? That’s ambitious, an expert says

While Noman and Georg’s findings represent an important step towards discovering a safe and effective birth control pill for men, there is still a long and uncertain path ahead before the pill could hit the market.

“If the compound continues to show all the parameters of safety, we can be hopeful that we can see this compound reach the market in five years,” Noman said.

But experts in the field say that timeline is ambitious, and that while the new pill is “exciting,” it’s hard to assess its true potential until human trials begin.

“The trials are so important because you have to make sure it is safe, and you never know until you try it in humans,” Dr. Christina Wang, an expert on contraceptives at The Lundquist Institute at Harbor-UCLA Medical Center, told Fortune.

How this pill is different

The University of Minnesota’s male birth control pill is one of many male contraceptive options that have shown progress in recent years. 

Clinical trials for “an IUD, for men” are anticipated to begin this year for Virginia-based biotech company Contraline, according to its website. 

And in her own work, Dr. Wang is leading a team of researchers who have developed a male contraceptive gel that is applied directly to the skin daily. The gel, which targets male hormones, is currently in clinical trials and is supported by the U.S. National Institute of Health’s National Institute of Child Health and Human Development, in collaboration with the Population Council.

But Noman and Georg’s pill represents a breakthrough because it’s a non-hormonal birth control that, when tested in mice, did not produce any side effects besides the reduction in sperm count.  

Hormonal birth control options like the gel, on the other hand, produce a wide range of side effects “like depression, decreased libido, and increased risk for cardiovascular disease,” Noman said.

And unlike the other options currently being developed, the compound can be administered orally. Dr. Wang said this is a key reason why the new pill has the medical community excited about its potential.

“This is the way to go,” Dr. Wang said. “It’s just that much easier to take a pill each day.” 

Reproductive control for all

Heather Vahdat is the executive director at the nonprofit Male Contraceptive Initiative, which helped fund the research behind the newest pill. 

Vahdat, who has been at the organization since 2018, said the Minnesota research presents an opportunity to enact long overdue social change in the world of contraception. By only having female birth control options available, “We’ve only been working with half of the resources we need to be effective,” she said. 

“Contraception is not a gendered thing,” Vahdat said. “This is about people having the ability to have better health outcomes by not having unintended pregnancies—for everyone to be able to control their own reproductive autonomy by being able to contracept individually or as a dyad.”

While it will likely be a few years before a male contraceptive hits the market, experts say the attention research like Georg and Noman’s has received is key to ensuring the project remains well-funded and on a path to fruition.

In the days following the publication of their research, their work has attracted several new investors. The more money involved, the faster a male birth control pill will hit the shelves, Georg said.

“From clinical trials to toxicology studies, everything is expensive,” she said. “With more investment, this can become a reality much faster.”