If it proves safe and effective, the gel could finally expand the very short list of contraceptive options that can be utilised by men.
"Many women cannot use hormonal contraception and male contraceptive methods are limited to vasectomy and condoms," study investigator Diana Blithe, said in a statement from the National Institutes of Health (NIH), which is funding the trial.
"A safe, highly effective and reversible method of male contraception would fill an important public health need."
The gel, applied to the back and shoulders once daily, contains a combination of a progestin compound and testosterone that is absorbed through the skin.
The progestin reduces sperm production to "low or nonexistent levels," the NIH statement said, while the testosterone will work to maintain normal sex drive and other functions that require the hormone. The researchers plan to enroll 420 couples in the trial, the statement added.
Christina Wang, another investigator involved in the study, told Gizmodo that she and her colleagues have been working on the gel for nearly a decade and testing it in small human studies since 2009, refining its balance of hormones for both safety and effectiveness.
"We've had over 200 men exposed to the medication, and we've never had any serious adverse events," she told Gizmodo. "But we will be monitoring everything very closely."
On social media, the news prompted strong reactions among women.
Though the gel still remains to be studied in large groups of men, many women expressed frustration, saying that a gel applied to the skin seems far more convenient than some of the birth control options currently available to women.
The pill, for example, can have side effects like nausea, headaches, and breast tenderness, and IUDs require an insertion procedure that many women find painful.
Male birth control is going to be rubbing a gel on your shoulders?! Nah y'all can swallow a pill every single night, get injections & implants like the rest of us.— Erin Charles (@ercharles15) November 30, 2018
Who do I write letters to? We have to stick foreign objects in our body and y'all talking about Gel for men?!— Jay ??♀️ (@Jay_liebe) December 2, 2018
Y'all don't understand how angry I am about this, fine to prod us with needles and implants and alter our hormones every day but first male birth control and it's a simple and convenient GEL, I'm outta here https://t.co/mSdSg7Togj— seagal (@lucybadlose) December 3, 2018
Well... I've had no shortage of painfully inserted IUDs dislodge and stab my uterus, but yes, let's invent a birth control GEL for men. ? #maleprivilege— Dr. Kehaulani Watson (@hehawaiiau) December 2, 2018
New Non-Invasive Male Birth Control Being Tested & Women Everywhere Say 'WTF'? https://t.co/5QW2HlkHPT
Scar from my implant, where's the gel for women at? pic.twitter.com/6mMMpUTq87— lisha (@aalishakenn) December 4, 2018
But – as HelloGiggles noted – other women seemed to celebrate the news as welcome progress.
LISTEN I understand the gel male birth control frustration bc us as women have to go through HELL, but let's be fucking thankful there's steps being taken in the right direction so we don't have to go through that hell!— astod (@baestod) December 3, 2018
So there's a male birth control being tested where you spray a gel on the mans arms and shoulders?? SHIIIIIT let me find out. Preventing pregnancy easier than putting on sunscreen!!— Sar? (@sarahashlynnn) November 30, 2018
It is true that the burden of contraception falls largely on women, who can choose from a bevy of birth control options, including the pill, a vaginal ring, IUDs, an arm implant, injections, and more.
This comes down partly to a mathematical reality, as Business Insider previously reported: It's harder to eliminate millions of sperm than it is to eliminate an egg or two each month.
"Women only ovulate one or two eggs a month," Stephanie Page, a University of Washington researcher who's also involved in the new gel trial, told Business Insider earlier this year.
"Men on the other hand, are making 1,000 sperm a second. So every time a man ejaculates, there's 15 to 100 million sperm."
But there are other factors, too. Previous attempts to develop male birth control have been hindered by side effects, including liver damage, and there's also been a lack of support for male birth control from pharmaceutical companies, Business Insider's report added.
The new gel, if effective, is still a long way off from your local pharmacy.
Gizmodo reported that the current clinical trial won't fully finish until 2022, and from there, the investigators will need to conduct more studies with thousands of additional men before the drug can get approval from the Food and Drug Administration.
But, if it does reach that point, the gel may help ease contraception burden faced by many women of reproductive age.
"The goal of the whole field of male contraceptive development is to try and create choices for men and for families, Page told Business Insider earlier this year.
"A lot of women can't use contraceptives, and men want to share the burden of contraception."
This article was originally published by Business Insider.
More from Business Insider: