WASHINGTON — The drug industry’s decade-spanning search for a female equivalent to Viagra took a major step forward Thursday, as government experts recommended approval for a pill to boost sexual desire in women.

However, the first-of-a-kind endorsement came with safety reservation due to drug side effects including fatigue, low blood pressure and fainting.

The panel of Food and Drug Administration advisers voted 18-6 in favor of Sprout Pharmaceutical’s daily pill, flibanserin, on the condition the company develops a plan to manage its risks.

The recommendation is a major victory for a drug sometimes hailed as “female Viagra,” but which has been plagued for years by concerns of lackluster effectiveness and safety issues. The FDA has rejected the drug twice since 2010. And a similar panel of FDA experts voted unanimously against the drug five years ago.

Thursday’s vote is non-binding but the FDA often follows the advice of its experts. An official decision is expected in August.

FDA’s experts acknowledged flibanserin’s effect is not very strong, but said there is a need for FDA-approved drugs to address female sexual problems.

“These are very modest results,” said Dr. Julia Heiman of the Kinsey Institute at Indiana University. “But on the other hand, even modest results can make a lot of difference when you’re at a certain point in the clinical problem.”

In general, women taking flibanserin reported between 0.5 and 1 more sexually satisfying event per month, compared with women taking a placebo. They also scored higher on questionnaires measuring desire and scored lower on measures of stress.

Flibanserin, which acts on serotonin and other brain chemicals, was originally studied as an antidepressant, but then repurposed as a libido pill after women reported higher levels of sexual satisfaction.

The effort to trigger sexual interest through brain chemistry is the drug industry’s latest attempt to address women’s sexual problems.