Women looking for a libido boost may find less success with Addyi—a libido drug commonly referred to as “female Viagra”—than previously thought, according to a review of clinical trial data published Monday in the American Medical Association’s Journal of Internal Medicine. The researchers found that the recently FDA-approved drug, clinical name Flibanserin, results in a mere “one-half an additional SSE”—meaning satisfying sexual event—”per month” on average.

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The study’s authors analyzed eight studies (five published, three unpublished) involving more than 5,900 women. They found, by pooling efficacy data, that the subjects experienced slightly fewer satisfying sexual events per month on average than what the original three clinical trial findings—the ones on which the FDA based its regulatory approval—had determined.

The earlier studies found that women experienced one additional satisfying sexual encounter per month on average, a supplement to their two to three regular preexisting ones, as the New York Times reports.

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Addyi-maker Valeant (VRX) took issue with the team’s methodology. The company sent Fortune a statement attributed to Dr. Tage Ramakrishna, Valeant’s chief medical officer, in an email. He said the new study “provided little additional context. Meta-analyses using pooled data carry less statistical weight than the prospective, randomized, placebo-controlled trials used to secure FDA approval.”

The drug has struggled in terms of sales since it hit the market in Oct.