A drug intended to treat low sexual desire in women won approval from US health regulators this week, but with a warning that side-effects such as dangerously lowered blood pressure and fainting were possible if the medication were taken with alcohol. The US Food and Drug Administration said that the drug, the first to be approved for the treatment of depressed libido in women, will be available only from healthcare professionals and pharmacies.It is to be sold under the brand name Addyi.The FDA has twice refused approval of the use of the active ingredient in Addyi, flibanserin, which is made by Sprout Pharmaceuticals.Its latest decision was made after an advisory panel concluded in June that sale of the drug should be approved but with strict measures to ensure that patients are fully aware of the risks.The drug has been nicknamed "the female Viagra" even though it does not work like Pfizer's blockbuster Viagra pill for men. Flibanserin has to be taken every day and, unlike Viagra, which affects blood flow to the genitals, flibanserin works on the brain.It is similar to drugs known as "selective serotonin re-uptake inhibitors", which include antidepressants such as Prozac.Originally developed by Germany's Boehringer Ingelheim, flibanserin was first rejected by the FDA in 2010 after a panel said the benefits did not outweigh the risks.Sprout bought the rights to the drug, conducted additional studies and resubmitted the application in 2013. The FDA rejected it again.The rejection sparked a lobbying campaign by Sprout, aided by some women's groups who accused the FDA of gender bias because it had approved Viagra for men.Flibanserin is designed for premenopausal women who lack sexual desire. ..