Tolerability considerations for gonadotropin-releasing hormone analogues for endometriosis.

INTRODUCTION: The second-line treatment of endometriosis-related pain symptoms includes injectable depot formulations of gonadotropin-releasing hormone analogs (GnRH-as). These drugs improve the symptomatology by inducing a hypoestrogenic status and a consequent regression of endometriotic implants. However, GnRH-a may cause a not negligible rate of adverse events, in particular vasomotor symptoms and bone mineral density loss, that may limit patients' adherence and safety on long-term treatment. Several strategies have been suggested to improve the compliance to treatment. AREAS COVERED: This narrative review aims to give an overview of the safety and tolerability of GnRH-a therapy and to present the different options of steroidal and non-steroidal add-back therapies in order to reduce the hypoestrogenic side effects. EXPERT OPINION: Side effects of long term GnRH-a treatment are particularly relevant. Although it has been known the efficacy of GnRH-as for treating endometriosis-associated pain, the best schedules of therapy in terms of duration and dosages are still to be defined. The ideal treatment schedule of GnRH-a is still a matter of debate as to the optimal add-back combination.