Prozac for PMS
Premenstrual Fluoxetine for PMDD

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In Premenstrual Syndrome (PMS), or as it is officially known, Premenstrual Dysphoric Disorder (PMDD), disabling emotional and physical symptoms appear during the week before menses (late luteal phase) and remit following onset of menses (follicular phase). Results of several studies have documented the efficacy of serotonin reuptake inhibitors for treating this disorder (JW Oct 15 1997, p. 164, and JAMA 1997; 278:983), and daily fluoxetine (Prozac) is the only FDA-approved therapy for PMDD. In this manufacturer-sponsored, multicenter, placebo-controlled trial, investigators evaluated whether premenstrual fluoxetine use, starting 14 days before the next expected menses and continuing only through the first full day of bleeding, also is effective.

A total of 260 women (age range, 18 to 45) with PMDD (i.e., those with =50% increases in PMDD symptom scores from the follicular to the luteal phase) were randomized to receive 10-mg fluoxetine, 20-mg fluoxetine, or placebo daily for approximately 2 weeks before menses for 3 cycles. During 3 months of treatment, 20-mg fluoxetine was associated with significant improvement in total symptom scores compared with placebo, whereas 10-mg fluoxetine was not. Compared with placebo, both fluoxetine doses were associated with improved mood-related symptoms, but the 20-mg dose was associated with improved physical symptoms as well.

Comment: These results confirm findings from smaller studies, which have indicated that premenstrual daily fluoxetine is effective for treating PMDD. The rapidity with which PMDD patients responded suggests that the mechanism is different from the mechanism by which fluoxetine acts to relieve depression.

Cohen LS el al. Premenstrual daily fluoxetine for premenstrual dysphoric disorder: A placebo-controlled, clinical trial using computerized diaries. Obstet Gynecol 2002 Sep: 100:435-44.