Summary

Fibromyalgia is a pain-related condition common in women and is present in about 5% of the population [1]. Its treatment involves physical exercise, psychotherapy (mainly behavioral–cognitive therapy), and antidepressant/anticonvulsant use as class IA evidence treatments [1]. Although in several cases this treatment fails or loses effectiveness over time, necessitating novel therapeutical agents.

Naltrexone is an opioid antagonist drug used for opioid addiction therapy. It also has anti-inflammatory and analgesic properties when used in low dosages [2]. Our group recently wrote a systematic review of low-dose naltrexone (LDN) for treating rheumatic diseases, including fibromyalgia [3]. In all seven published articles on LDN for fibromyalgia, a benefit was observed in pain reduction and improvements in fibromyalgia questionnaires [3]. To the best of our knowledge, no study using LDN as the first option of treatment has been conducted. Therefore, in this study we aimed to evaluate the effects of LDN as the first line of therapy in patients with fibromyalgia.