Article

Epidemiologic surveys have estimated that as many as 75% of women with regular menstrual cycles experience some physical and psychological symptoms premenstrually.¹ Vitamin B₆ (pyridoxine hydrochloride) use is one of the numerous treatments suggested for premenstrual syndrome (PMS). Wyatt and colleagues have systematically reviewed trials comparing the efficacy of vitamin B₆ with placebo in women with PMS. Although their meta-analysis includes a few more trials than a previous review published in 1991,² they, too, conclude that “there is insufficient evidence of high enough quality to give a confident recommendation for using vitamin B₆ in the treatment of premenstrual syndrome” (p 1378).

The authors used extensive data sources and rigorous selection criteria to identify 10 relevant trials. They used two different scales to evaluate the methodologic quality of each trial. Nine trials (after excluding 1 trial that caused statistical heterogeneity) were included in the meta-analysis, although only four were rated as high-quality studies on either of the two scales. The nine trials differed in many ways, including the outcomes, the dosage of vitamin B₆, and whether the intervention was vitamin B₆ alone or as the ingredient of a multivitamin. Moreover, the authors did not consider the severity of premenstrual symptoms.

This is an important variable because women who meet criteria for premenstrual dysphoric disorder, the more severe form of PMS, usually do not respond to more conservative interventions, such as vitamin B₆.³ The lack of a dose response adds to the uncertainty about the effectiveness of vitamin B₆ for PMS.

This review highlights the need for well-designed trials to compare the use of vitamin B₆ with placebo to establish more accurate recommendations for treatment. In the meantime, what do clinicians tell patients? Given that vitamin B₆ is readily available, relatively inexpensive, and generally has minimal adverse effects in doses of less than 200 mg, clinicians may suggest that patients take = 100 mg per day as a conservative treatment option before considering drugs with stronger evidence of effectiveness such as selective serotonin reuptake inhibitors.