According to their findings, published in the Drugs and Therapeutics Bulletin (DTB), the trials showed sufferers who used the mouth spray, called Sativex, experienced small improvements compared to those who received a placebo. However, the reviewers say in many of the studies Sativex was used for relatively short periods – from six weeks to four months.
They also say two of the trials included doses that exceeded the 12 daily sprays for which the preparation is licensed and one trial did not have sufficient numbers of participants to validate the results.
James Cave, GP and DTB editor, said the findings were disappointing.
He said: "MS is a serious and disabling condition, and it would be great to say that this drug could make a big difference, but the benefit is only modest."