Scientists have gotten one step closer to developing a reliable and side-effect free birth control for men.

A male contraceptive gel was found to be 100 percent effective at preventing conception in a recent trial in primates.

The product, called Vasalgel, is meant to offer a less invasive alternative to a vasectomy. The product is injected into the sperm-carrying tube – or the vas deferens – where it acts as a long-lasting (but easily reversible) barrier.

“Men’s options for contraception have not changed much in decades. There’s vasectomy, which is poorly reversible, and condoms," said lead author Catherine VandeVoort of the California National Primate Research Centre. 

"If they knew they could get a reliable contraceptive that could also be reversed I think it would be appealing to them." 

The non-profit organization known as The Parsemus Foundation, which funded the work, intends to start a human trial as soon as funding comes in.

“One of the great things about the monkey model is that the male reproductive tract is very similar to humans and they have even more sperm than humans do,” said VandeVoort. “Chances are, it’s going to be effective in humans.”

A number of different male contraceptive options have been partially developed and discussed in recent months, but scientists have struggled to eliminate unwanted side-effects like depression and acne, which are commonly linked to hormone-altering gels, pills and injections.

Vasalgel, however, doesn’t impact sperm production and hormone levels aren't altered, meaning such side-effects aren’t an issue. Just like with a vasectomy, sperm is still produced when Vasalgel is injected, but is naturally absorbed by the body instead of being ejaculated.

 “They wouldn’t have to worry about it on a day-to-day basis,” said VandeVoort. “This would be more akin to an IUD [the coil] in women.”

h/t The Guardian