Stopping relapses

In short

Relapses and new lesions come mainly from immune cells that travel from the blood into the brain and spinal cord.

Stopping them prevents the damage each attack leaves behind, and it is where treatment has advanced most.

Several medicines now prevent most relapses in many people. The open questions are safety, cost, how long to treat and whether early, strong treatment changes the long-term course.

Where we are

• For most people relapses can be stopped. B-cell therapies, S1P modulators, natalizumab and immune reconstitution cut relapses by half or more against placebo or older medicines.
• The open questions are about use, not whether: when to start the strongest medicines, when to stop, and dosing by blood level.
• BTK inhibitors are the next class. Fenebrutinib beat teriflunomide in two phase 3 trials reported in 2026, and tolebrutinib did not.
• Safety over decades, in pregnancy, in children and in older people is where most new evidence now comes from.

Written by the editors from the records below. Last reviewed 6 November 2026. Not yet reviewed by an MS specialist.

The evidence

What comes next

Further reading

References

The sources behind this area's background are listed with its Research background in MS in depth. Every trial, hypothesis, review and lab study above links to its own record.