Hormone-free male birth control pill shown safe in human trials, raising hopes for new contraceptive option

A new male contraceptive pill that doesn’t use hormones has passed early-stage human trials without any negative side effects, researchers say.

The drug, designed to reversibly reduce sperm count, was tested on 16 male volunteers. This development could offer men a new alternative to condoms or vasectomy, which have long been the only options for male contraception.

Prior attempts at creating a male contraceptive pill often resulted in unwanted effects such as weight gain, acne, mood swings and changes in sex drive.

Meanwhile, although women have a range of birth control options, these also typically come with potential side effects. More than a third (37 per cent) of woman report a negative experience will a contraceptive pill.

What sets this new pill apart, scientists say, is its hormone-free formula, which may mean far fewer adverse effects compared to earlier efforts.

“Since nearly half of all pregnancies in the US and worldwide are unintended, there is a critical need for additional contraceptive options for men and women,” researchers from YourChoice Therapeutics explained.

This contraceptive uses a chemical called YCT-529, aiming to block vitamin A metabolites from binding to certain receptors in the testes, thereby stopping sperm production.

Professor Alan Pacey, an andrologist at the University of Manchester who was not involved in the study, told BBC Radio 4’s Today programme: “This molecule targets a compound which is related to vitamin A, retinoic acid, and we have known for a long time that this compound is important in how sperm are produced in the testis, making it the perfect target for a male contraceptive pill. It is able to inhibit that process without altering the sex hormones, which give men a sex drive.”

Previous animal studies using this compound have shown that it can induce reversible infertility without causing side effects.

In these most recent trials, the 16 male volunteers aged 32 to 59 took the drug twice in increasing doses—10mg, 30mg, 90mg, and 180mg—while some received a placebo to compare results. Side effects and hormone levels were monitored for 15 days.

The authors of the study wrote: “Administration of single oral doses of 10–180 mg YCT-529, fasted, and 30 mg, fed, is well tolerated by healthy male subjects. YCT-529 does not demonstrate an adverse cardiac safety profile, or change in haematology, coagulation or serum chemistry parameters, hormone or pro-inflammatory cytokine levels, sexual drive and mood, and shows good bio-availability (with no clear food effect).”

Dr Pacey described the results as an “exciting step forward,” but warned that the medication has yet to be tested in the real world to confirm its effectiveness in preventing pregnancies.

He pointed out, “It takes three months to produce sperm from start to finish and so if you were to start taking any pill, not just this one, you would need to have the sperm that are currently on the production line to be moved from the system. So, there will be a lag between starting to take the pill and it having its full contraceptive effects.”

He also pointed out that bringing the pill to market remains a significant financial hurdle.