The quest for an easy-to-use male birth control alternative to the condom appears to be forging ahead. In the new issue of the journal Cell, scientists are optimistic about a new pill that temporarily stops the production of sperm — without any damaging side effects. Sound too good to be true? Here's what you should know about the discovery:

How does the pill work?
Researchers discovered that a chemical called JQ1 can make a man's testicles "forget" how to produce sperm, says Maggie Fox at NBC News. But that's not all: The molecule pulls double-duty as the centerpiece of an experimental cancer drug that similarly makes cancerous cells "forget" how to be tumors. Researchers correctly guessed that it could do the same with healthy sperm cells. JQ1 works as a pill because it can penetrate  the boundary between blood vessels and a man's testis, where it targets a protein called BRDT that's responsible for sperm production. Mice given the compound not only produce much fewer sperm overall, but the cells they do produce are "much worse swimmers," says Tim Barribeau at io9.

Why is this pill more desirable than others? 
This kind of non-hormonal treatment is advantageous because it doesn't change testosterone levels. Other research into male birth control pills has "largely focused on manipulating male sex hormones," says Salynn Boyles at WebMD, which can have a number of unfortunate side-effects, including blood clots, weight gain, and decreased sex drive. For those reasons, big drug companies have been hesitant to endorse any birth control pills for men. Researchers are excited about JQ1 because its sperm-inhibiting power is completely reversible: When the team stopped giving the pill to mice, "they became fertile again and fathered healthy mouse pups," says NBC News' Fox.  

How big of an advancement would a male birth control pill be? 
It could be huge. "Despite the availability of birth control for women and condoms for men, as many as 49 percent of births in the U.S. were unplanned in 2006, according to a 2011 study by the Centers for Disease Control and Prevention," says Shannon Pettypiece at Bloomberg. A pill could potentially help lower that rate.

Were there any side effects?
None that researchers could detect. The team will continue to test the compound in cancer trials while at the same time monitoring if the male patients become infertile. "We are probably not talking about something that is going to be available in the next two years or even five," says Dr. William Bremner, who wrote the accompanying commentary in Cell. "But this research represents a new biologic approach and it is certainly promising."

Sources: Bloomberg, NBC News, io9, WebMD