A Cochrane review ¹ included nine studies with 649 participants. The daily dose of amitriptyline was 25 mg to 50 mg, and some studies had an initial titration period.

There was no first or second tier evidence for amitriptyline in the treatment of fibromyalgia. Using third tier evidence the RR for at least 50% pain relief, or equivalent, with amitriptyline compared with placebo was 3.0 (95% CI 1.7 to 4.9), with an NNT of 4.1 (2.9 to 6.7). There were no consistent differences between amitriptyline and placebo or other active comparators for relief of symptoms such as fatigue, poor sleep, quality of life, or tender points. More participants experienced at least one adverse event with amitriptyline (78%) than with placebo (47%). The RR was 1.5 (1.3 to 1.8) and the NNH was 3.3 (2.5 to 4.9).

Comment: The quality of evidence is downgraded by sparse data.