Objective  To determine the effectiveness of gonadotrophin-releasing hormone analogues (GnRHa) with and without hormonal add-back therapy in the management of premenstrual syndrome.

Design  Randomised controlled trials were identified by searching multiple databases.

Setting  Exeter and North Devon Research and Development Support Unit and Keele University Academic Unit of Obstetrics and Gynaecology.

Population  Women with pre-diagnosed premenstrual syndrome and/or premenstrual dysphoric disorder.

Methods  A meta-analysis of published randomised placebo-controlled trials assessing the use of GnRHa in the management of premenstrual syndrome. The standardised mean difference for each individual study and subsequently an overall standardised mean difference were calculated after demonstrating the consistency or homogeneity of the study results.

Main outcome measures  Overall improvement in premenstrual symptomatology and effectiveness of GnRHa with additional hormonal add-back therapy were the main outcome measures assessed in this analysis. A secondary analysis was performed to assess the effectiveness of GnRHa in treating physical and emotional symptoms.

Results  Overall standardised mean difference for all trials that assessed the efficacy of GnRHa was −1.19 (95% confidence interval [CI] −1.88 to −0.51). The equivalent odds ratio was 8.66 (95% CI 2.52 to 30.26) in favour of GnRHa. GnRHa were more efficacious for physical than behavioural symptoms, although the difference was not statistically significant. The addition of hormonal add-back therapy to GnRHa did not appear to reduce the efficacy of GnRHa alone; standardised mean difference 0.12 (95% CI −0.35 to 0.58).

Conclusions  GnRHa appear to be an effective treatment in the management of premenstrual syndrome. The addition of hormonal add-back therapy to reduce side effects does not reduce efficacy.