A new, effective form of birth control pills for men could be available in as little as ten years from now after the experimental oral drug known as 11-beta-MNTDC passed its first round of safety tests.

“Our results suggest that this pill, which combines two hormonal activities in one, will decrease sperm production while preserving libido,” Dr. Christina Wang from L.A. Biomen said in a report.

The phase 1 clinical trial recruited 40 healthy men, 14 of whom received 200 mg of the birth control drug, 16 receiving 400 mg and the remaining receiving a placebo. The study participants took the pills daily with food 28 days in a row. Men taking the drug experienced a drop in testosterone levels without experiencing any severe side effects.

However, some men reported having some mild side effects from taking the pill, such as fatigue, acne, or headaches. Those are similar to side effects commonly reported by women who take the contraceptive pill. At least five men reported having their sex drive decrease, with at least two men reporting having trouble with erectile dysfunction.

No study participant stopped taking the drug because of the effects, the report said.

The study also found that the drug’s effects were reversible after the men stopped taking the pill.

Read the full study here