Naltrexone for fibromyalgia treatment: what does the evidence show?

Some fibromyalgia patients take low-dose naltrexone for their pain, but it is off-label. A systematic literature review examined its effects on the disease.

Key points of the study

Naltrexone: what is it?

Originally, naltrexone was mainly used for addiction. It is often prescribed for an existing opiate addiction or - at least in the USA - also for alcoholism.

The drug is an opiate antagonist. It is assumed that the pain-reducing effect in fibromyalgia is related to the fact that the central blocking of opioid receptors, as occurs at a low dosage, leads to an endorphin rebound. This then leads to pain relief.

Naltrexone use is so far off-label

More and more patients are therefore taking the drug for their pain. But the therapy is considered off-label. Many doctors therefore are in need of evidence for or against taking naltrexone. 

A current literature search has investigated this question. However, the available data is relatively small. Only three randomised studies could be included in the search and evaluated. It is therefore important that further research projects take up the topic, according to the authors.

Medication for pain, and for quality of life

Particularly in the case of severe pain, the patients' quality of life often suffers. The study authors therefore wanted to know whether taking naltrexone actually leads to pain reduction and an improved quality of life for fibromyalgia sufferers.

The answer is: yes. In all three studies, this goal was achieved. But the results should be treated with caution. The data available is very small, with limited studies and clear bias.

Naltrexone: Its influence on inflammation parameters is questionable

While the question of a pain-relieving effect was clear in the included studies, the effect on inflammation values is different.

Only one study showed a reduction in the parameters after taking naltrexone. Another describes that baseline blood sedimentation rate may predict the effectiveness of naltrexone. Again, further research is needed to confirm and develop these findings.

Naltrexone: a viable application for fibromyalgia?

Naltrexone seems to be a promising candidate for pain therapy in fibromyalgia. However, the data on which this assessment is based is extremely limited. Further studies on the topic are currently being conducted and will hopefully provide more information.