WASHINGTON — The Food and Drug Administration approved the first prescription drug designed to boost sexual desire in women on Tuesday, a milestone long sought by a pharmaceutical industry eager to replicate the blockbuster success of impotence drugs for men.
But stringent safety measures on the daily pill called Addyi mean it will probably never achieve the sales of Viagra, which has generated billions of dollars since the late 1990s.
The drug’s label will bear a boxed warning, the most serious type, alerting doctors and patients that combining the pill with alcohol can cause dangerously low blood pressure and fainting. That risk can occur when taking the drug with other commonly prescribed medications, including antifungals used to treat yeast infections.
‘‘This is not a drug you take an hour before you have sex. You have to take it for weeks and months in order to see any benefit at all,’’ said Leonore Tiefer, a psychologist and sex therapist who organized a petition last month calling on the FDA to reject the drug.
Under an FDA safety plan, doctors will only prescribe Addyi after completing an online certification test demonstrating that they understand its side effects. Pharmacies will also have to be certified.
‘‘Patients and prescribers should fully understand the risks associated with the use of Addyi before considering treatment,’’ said Dr. Janet Woodcock, director of the FDA’s drug center, in a statement.
Sprout Pharmaceutical’s drug is intended to treat women who report emotional stress due to a lack of libido. Its approval marks a turnaround for the FDA, which rejected the drug twice because of lackluster effectiveness and side effects. The decision represents a compromise between two camps that have feuded for years.
On one side, Sprout and its supporters have contended that women desperately need FDA-approved medicines to treat sexual problems. But safety advocates and pharmaceutical critics warn that Addyi is a problem-prone drug for a questionable medical condition.
Beginning with the drug’s launch in mid-October, doctors who frequently see patients complaining about a loss of sexual appetite will have a new option.
‘‘Women are grasping, and I feel like we need to offer them something that acknowledges that, and that we can feel safe and comfortable with,’’ said Dr. Cheryl Iglesia, with the American Congress of Obstetricians and Gynecologists. Iglesia said she has occasionally resorted to prescribing testosterone creams to boost women’s libido, a use not approved by the FDA.
The search for a pill to treat women’s sexual difficulties has been something of a holy grail for the pharmaceutical industry. It was pursued and later abandoned by Pfizer, Bayer, and Procter & Gamble, among others. But drugs that act on blood flow, hormones, and other biological functions all proved ineffective. Addyi, known generically as flibanserin, acts on brain chemicals that affect mood.