To assess the possible efficacy of fluoxetine hydrochloride in severe PMS (premenstrual syndrome, luteal phase dysphoric disorder), an open trial of this medication was undertaken on women with severe PMS. Of 38 patients seeking evaluation of PMS, 35 met the criteria for diagnosis, and 21 had mild symptoms and were treated symptomatically. Fourteen had more severe symptoms persisting for more than 5 to 6 days of the month, and 11 elected to participate in an open trial of low-dose (20 mg) fluoxetine, an antidepressant. Ten continued treatment for 3 to 20 months, with moderate to marked relief of symptoms during treatment and without problematic side effects (one patient was given 40 mg daily; the remainder received 20 mg daily). On discontinuing therapy, seven have had persisting remissions, and two have returned for another cycle of fluoxetine therapy, with relief. It is unclear whether such a strong positive response to fluoxetine, an antidepressant with particularly good effects in ''atypical depression,'' indicates that the women affected by severe PMS have a cyclic, hormonally induced change in brain chemistry causing a depressive type of condition, or whether they have a true (atypical) mild depression with brief remission due to ''perifollicular euphoria'' in the estrogenic follicular phase.
