Tramadol for treating neuropathic pain
We found low-quality evidence that oral tramadol has any important beneficial effect on pain in people with moderate or severe neuropathic pain. There is very little evidence from which to take these conclusions.
Neuropathic pain is pain coming spontaneously or abnormally from damaged nerves. It is different from pain messages that are carried along healthy nerves from damaged tissue (a fall or cut, or burns). Neuropathic pain is often treated by different medicines (drugs) to those used for pain from damaged tissue, which we call painkillers.
Opioid painkillers (drugs like morphine) are sometimes used to treat neuropathic pain. Morphine is derived from plants, but many opioids are made in a laboratory rather than being extracted from plants. Tramadol is a laboratory-synthesised opioid drug.
Characteristics of the drug
In January 2017, we searched for clinical trials in which tramadol was used to treat neuropathic pain in adults. Six studies met the inclusion criteria, randomising 438 participants to treatment with tramadol or placebo. Study duration was between four and six weeks. Not all reported the outcomes of interest.
Our definition of a good result was someone who had a high level of pain relief and was able to keep taking the medicine without side effects that made them stop treatment.
Three small studies reported that pain was reduced by half or better in some people. Pain reduction by half or better was experienced by 5 in 10 with tramadol and 3 in 10 with placebo. Side effects were experienced by 6 in 10 with tramadol and 3 in 10 with placebo, and 2 in 10 with tramadol and almost no-one with placebo stopped taking the medicine because of side effects.
Quality of the evidence
The evidence was mostly of low or very low quality. This means that the research does not provide a reliable indication of the likely effect and that the likelihood is very high that the effect will be different from what is shown in the analysis of these trials. Small studies like those in this review tend to overestimate results of treatment compared to the effects found in larger, better studies. There were also other problems that might lead to over-optimistic results. The low-quality evidence and the lack of any important benefit mean that we need new, large trials before we will know if tramadol is useful for the management of neuropathic pain.