How does amitriptyline work

Cochrane

Our understanding of fibromyalgia (a condition that causes persistent, widespread pain, tenderness, insomnia, and fatigue) is poor. General pain relievers like acetaminophen and ibuprofen are usually not considered effective in fibromyalgia. Drugs, some of which are used to treat epilepsy or depression, can work very well in some people with fibromyalgia, as well as other forms of chronic pain that may be associated with nerve damage (neuropathic pain).

Amitriptyline belongs to the class of antidepressants recommended for the treatment of fibromyalgia. Although amitriptyline is widely used to treat fibromyalgia, a 2012 review found no good quality evidence to support the drug's use. Most of the studies included were small, old, and methods or results were used that gloss over the benefits from our current perspective.

The present review is an update of the 2012 review, which included both fibromyalgia and neuropathic pain. Now there is a separate review on neuropathic pain. This review examines how effective amitriptyline is in treating fibromyalgia. To assess a “good effect”, a definition is used that includes both strong pain relief and the possibility of taking the tablets over a long period of time without severe adverse effects from side effects.

Searches for new studies were conducted in March 2015, with only two additional small studies eligible for inclusion being found. Neither study contained any good quality evidence on benefits and harms. Still no studies have been found that can provide trustworthy and reliable answers, as most studies were relatively old and they used methods or described results that gloss over the benefits from our current point of view. This is disappointing, but some helpful comments can be made about the medicine.

Amitriptyline is believed to provide good pain relief for some people with fibromyalgia, although we cannot be sure. We can only assume that about 1 in 4 people (25%) have more good analgesic effects than amitriptyline than a placebo. Compared to placebo, 1 in 3 people (31%) are more likely to have one or more side effects. These are usually not serious, but they can be stressful for the patient and affect the use of the medicine. Based on the information available, neither of the two statements is reliable.

The main message is that amitriptyline may have very good analgesic effects in some patients with fibromyalgia, but this is only a fraction; amitriptyline is not effective in most people.