Eighteen women with severe premenstrual syndrome (PMS) (premenstrual dysphoric 
disorder, PMDD) were treated openly with paroxetine for 10 consecutive menstrual 
cycles. Dosage was flexible (5-30 mg/day); also, the patients were free to chose 
between continuous medication and medication in the luteal phase only. The 
rating of premenstrual irritability, depressed mood, increase in appetite, and 
anxiety/tension was markedly lower during treatment with paroxetine than before, 
and this reduction in symptomatology appeared unabated for the entire treatment 
period. Sedation, dry mouth, and nausea were common side-effects but declined 
during the course of the trial; in contrast, reduced libido and anorgasmia, 
which were reported by almost 50% of the participants, were not improved with 
time. The results indicate that the beneficial effects as well as the sexual 
side-effects of serotonin reuptake inhibitors persist unchanged for at least 10 
consecutive cycles of treatment.