April 30 (HealthDay News) -- Amitiza (lubiprostone) has been approved by the U.S. Food and Drug Administration to treat irritable bowel syndrome accompanied by constipation (IBS-C) in women 18 and older. It's the first IBS-C treatment that's been approved by the FDA.

IBS -- with symptoms including cramps, abdominal pain, bloating, constipation and diarrhea -- affects twice as many women as men, the agency said in a statement.

Amitiza's safety and effectiveness were evaluated in two studies involving 1,154 people with IBS-C, more than 90 percent of whom were women. More people treated with the drug said their symptoms were moderately or significantly relieved than those who took a non-medicinal placebo.

The effectiveness of the drug in men wasn't conclusively established during clinical testing, the FDA said.

Common side effects included nausea, diarrhea and abdominal pain. More serious yet rarer adverse reactions could include urinary tract infections, dry mouth, fainting, swelling of the extremities, difficulty breathing and heart palpitations, the agency said.

The 8-microgram dose is meant to be taken twice daily with food and water. Amitiza is produced by Maryland-based Sucampo Pharmaceuticals and Illinois-based Takeda Pharmaceuticals America.