Cannabis in multiple sclerosis: a randomised, double blind, placebo controlled trial

Can cannabis help people with MS?

What was this study about?

Multiple sclerosis (MS) is the most common disabling neurological condition affecting young adults. Around 85,000 people in the UK have MS. 9 out of every 10 people with MS experience muscle spasms or muscle spasticity at some point in their illness. This can be very distressing.

The CAMS trial aimed to find out whether cannabis could reduce these symptoms. People who agreed to take part in this trial were allocated at random to receive capsules containing either:

  • Cannabis oil
  • Placebo in capsules that looked like the capsules containing cannabis oil
  • Tetrahydrocannabinol (THC), the major active ingredient in cannabis
  • Placebo in capsules that looked like the THC capsules

All of the capsules were given for three months. Doctors used a measure called the Ashworth Scale to see if muscle spasticity had reduced at the end of their treatment.

This trial was carried out in partnership with the Peninsula College of Medicine and Dentistry, Derriford Hospital and the University of Plymouth.

What difference did this study make?

The trial found that cannabis had no significant effect on muscle spasticity, when measured using the Ashworth scale. However, the majority of people who took part in the trial and took cannabis reported significant improvement in their spasticity, sleep quality and pain. There was also some evidence that cannabis treatment led to improved mobility. There was no evidence of more serious adverse events in those receiving cannabis.

The trial was later extended for a year. 80% of the participants in the original CAMS trial took part in this extension. The results of this trial suggested that cannabis based drugs might slow the development of disability over time.

Type of study

Randomised trial

Who funded the study?

The Medical Research Council.

When did it take place?

This trial began recruiting people in 2000. It closed to recruitment in 2002.

Where did it take place?

Participants attended 33 centres across the UK

Who was included?

633 people with MS took part in this trial