Living with MS

Relapse

What it is

A relapse, also called an exacerbation or flare, is a new symptom or a clear worsening of an old symptom that lasts at least 24 hours and is not caused by something like heat or illness. Relapses often build over days and then slowly improve. They are a sign of new inflammation in the nervous system.

What you might notice

New or clearly worse symptoms that persist for more than a day and are not tied to heat, a fever, or an infection. Relapses often creep in over hours or days, not minutes.

Why it matters for you

Relapse is one of the most important distinctions in MS care. Having a clear definition can reduce second-guessing and make symptom timelines easier to describe.

Questions to ask your doctor

Has this lasted more than 24 hours?
Could this be a pseudo-exacerbation (heat, infection, stress)?
Should I come in for an exam?
Would steroid treatment help?
Should I go to the ER?

See all something feels off today questions

Frequently asked

How do I know if this is a real relapse?

A relapse lasts at least 24 hours and is not tied to heat, a fever, or an infection. If symptoms fade when you cool down or the illness passes, it is more likely a pseudo-exacerbation.

What happens when someone reports a possible relapse?

MS teams usually ask when symptoms started, what changed, whether there was heat or illness, and whether the symptoms are new or clearly worse. That information helps them decide whether a visit, scan, or steroid treatment is relevant.

Symptom timeline for flares

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