(CNN) - Birth control pills aren't a revolutionary concept, but they are if designed for men.
Researchers have spent decades trying to develop a birth control pill for men and according to a new study, they may finally be making headway.
The results were presented at a recent Endocrine Society meeting.
They indicate that the proposed pill reduces hormone levels responsible for sperm production, including testosterone, without any major side effects.
Participants were randomly assigned to one of four groups.
One group received a placebo, and the other three received varying doses of the medication.
After 28 days, testosterone levels in all three groups taking the medication were comparable to levels seen after castration.
The group getting the highest dose also had a significant reduction in two hormones that regulate testosterone and sperm production.
Nine participants reported decreased libido.
The main purpose of the study was to find an effective dosage.
More research would have to be done before any pill could go into production.
The study's sample size is too small to definitively evaluate potential side effects for the general population, the reports states.
Also, the duration was too short to evaluate the potential for liver damage.
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