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Call it a flare-up, an exacerbation, an attack, or a relapse. Whatever you call it, it's not something you expect. When you have relapsing-remitting multiple sclerosis ( MS), you can go days or years without major changes in your symptoms. Then, suddenly, things change.

You'll work closely with your doctor to feel better. You can also reset your schedule to take special care of yourself. Exercise, stretching, and relaxation can help you manage MS symptoms -- and they boost your mood, too.

Symptoms of a True Flare

Here's how to tell if you're having a relapse of MS, when the illness is active again:

  • You develop a new symptom of MS. For example, you’ve never had vision problems before, and suddenly you can’t see clearly out of your left eye.
  • A regular problem gets worse. Maybe you’ve had some numbness in your left leg before, but now you can’t feel anything below your knee.
  • Your symptoms last 24 hours or longer. A relapse means a change in your brain, called a lesion. "If a symptom lasts less than 24 hours, it’s something transient that’s not related to a new lesion," says Edward Fox, MD, director of the MS Clinic of Central Texas.
  • Symptoms level off after a while and stop getting worse.

MS flares can last days, weeks, or even as long as a year.

"Then they usually do improve, but recovery can be quite slow," says Bruce Cohen, MD, of the Northwestern University Feinberg School of Medicine. You may recover completely, or you could have some permanent loss of function or sensation.

MS False Alarms and What Causes Them

Sometimes, you may fear you're having a relapse, but a different issue is to blame for your symptoms.  Once the trigger is gone, your symptoms should clear up, too. You can have muscle problems, numbness, or blurred vision after the following triggers:

  • Alcohol. One drink can worsen coordination for some people.
  • Cold or flu. Fever or an infection can feel like a flare-up. MS symptoms go away fairly quickly after the illness passes.
  • Heat or cold. Hot or humid weather, exercise, hot showers, and sunbathing can trigger symptoms such as blurred vision. Cold can bring on spastic muscles.
  • Poor sleep position. Morning numbness that goes away after you shake it out is not likely to be a flare-up, even if it happens every day. You just slept wrong.

Ordinary Fatigue or MS Relapse?

If you’re overworked, stressed, or not getting enough sleep, MS symptoms may trouble you more than usual. Rest and take extra time for yourself to get back on track.

If fatigue goes on even after you’ve rested -- especially if it’s extreme and keeps you from your regular activities -- check with your neurologist. Continued fatigue can be a sign of a flare-up.