Introduction

This information is for people who have multiple sclerosis. It tells you about botulinum toxin, a treatment used to help muscle spasms in multiple sclerosis. It is based on the best and most up-to-date research.

Does it work?

We're not sure. If you have muscle stiffness or spasms because of multiple sclerosis (MS), botulinum toxin aims to help by relaxing your muscles. But we need more research before we can say how well this treatment works.

What is it?

Injections of botulinum toxin damage the nerves that tell your muscles to contract (tighten up). Doctors use just a small amount of the toxin to relax your muscles.

The brand names for botulinum toxin are Botox and Dysport. You've probably heard of people using this treatment to relax the muscles in their face and reduce wrinkles. The effects of the toxin wear off over time. One injection lasts about 12 to 16 weeks.

If you have a fairly specific group of muscles that are stiff or get spasms, your doctor may recommend botulinum toxin. But the treatment should be given only by a specialist, alongside physiotherapy or other therapies to help improve your movement.^[2]

How can it help?

Injections of botulinum toxin can help stop your muscles contracting or twitching when you don't want them to.

One small study found that the injections made a slight difference to how far people could move their legs.^[101] By easing spasms, botulinum toxin helped people to sit and lie with their knees slightly farther apart, so their thighs didn't rub together so much. This made it easier for them to wash between their legs too.

The research hasn't looked at whether it's easier to move or do things for yourself if you have botulinum toxin injections.

We need more research to know for certain how helpful botulinum toxin is.

How does it work?

Your nerves release a chemical that tells your muscles to contract. Botulinum toxin stops your nerves releasing this chemical. So your muscles should relax.

Can it be harmful?

Doctors try to be very careful when they give you these injections so that they block only the nerves to the stiff muscles. But some of the toxin might spread into other muscles. This is rare. But if you get any problems with swallowing, talking, or breathing after one of these injections, get medical help straight away.^[102]

And sometimes it's hard to predict what will happen if you have these injections. Relaxing one muscle might make another one contract.

In one study, people treated with injections of botulinum toxin said they had muscle weakness more often than people who had injections that didn't have any drug in them (called placebos).^[101] The side effects were more common when a higher dose of botulinum toxin was used.