MS Relapses: Causes, Symptoms and Treatments

Patient Expert

The majority of people diagnosed with multiple sclerosis have a relapsing form of the disease, characterized by unpredictable episodes (called relapses or exacerbations) of acute worsening of neurologic function. During a relapse, you might experience new symptoms and/or a worsening of previous or existing symptoms.

What causes a relapse?

Relapses are caused by acute inflammation in the central nervous system which can cause a variety of symptoms. Sometimes relapses are marked by new lesions in the white matter of the brain or spinal cord which can be seen on MRI scans. Neurologists will often prescribe a 3- or 5-day course of high-dose intravenous steroids to reduce inflammation and speed resolution of a relapse.


With the onset of a relapse, you may experience a dramatic change in symptoms, such as muscle weakness which makes lifting your arm difficult or a case of optic neuritis resulting in temporary blindness or altered color vision in one eye. Or perhaps you suddenly have trouble with slurred speech or bladder control. A relapse is defined by new or worsening symptoms which last for more than 24 hours and are separated by more than 30 days from a previous relapse.

While symptoms of a relapse may be dramatic, they can also be more subtle. Numbness, tingling, or other altered sensations are very common MS symptoms which you might notice much of the time. However, numbness that begins to spread or becomes more intense over the course of a day or two may indicate an impending relapse. Loss of sensation can be more than annoying, it can become dangerous. Call the doctor when you notice new or worsening numbness that doesn’t go away.

Foot drop is a common symptom of MS that involves weak ankle muscles which make it hard to flex the foot. Foot drop may cause you to trip as the toes of the foot drag or get caught on surfaces as you walk. People with MS who experience foot drop may develop an exaggerated gait to avoid tripping. Working with a physical therapist who may prescribe a specially designed ankle brace can be helpful. If you develop a new case of foot drop, call your doctor.

Loss of positional awareness (called proprioception) caused by disrupted nerve signals can impair coordination and balance. Lack of proprioception may cause tripping or make you feel clumsy when you reach for things. Persons who have difficulty with proprioception often use visual cues to maintain body awareness. Call your doctor if you suddenly notice that you have difficulty maintaining balance, especially in the dark or when your eyes are closed.

A relapse may cause noticeable weakness in the limbs. Weakness in the legs can make your legs feel like they weigh fifty pounds. Weakness in the hands or arms can make tasks such as opening jars seem impossible. Most often it is the combination of symptoms which is most troubling. Muscle weakness, spasticity, numbness, and a loss of balance during a relapse can make you feel uncoordinated and unsteady on your feet.

Symptoms of a relapse do not always need to be sensory or physical. MS can affect cognitive functions involving memory, concentration, language, and information processing. It can also affect mood causing depression, anxiety, mood swings, or inappropriate laughing or crying. Any new problems you may have with memory, thinking clearly, problem solving, or changes in mood may be signs that you are in the midst of a relapse.

Other more subtle signs of a relapse include increased fatigue or pain. It can be difficult to determine whether fluctuating fatigue levels are just part of your MS or if they warn of a relapse. Sometimes you may not notice small increases in MS symptoms until you are so fatigued and tired that you can’t seem to muster the energy or strength to complete normal daily tasks. When you are having trouble keeping up with life, it’s a good idea to call your doctor. It might be a relapse.


Do heat or stress cause a relapse? No. An increase in body temperature, even as small as one degree, can interfere with nerve signals resulting in a temporary increase in MS symptoms (called a pseudoexacerbation). Heat does not cause permanent neurological damage and symptoms will usually return to normal once the body cools off. While stress can make us feel worse, there is no conclusive evidence that stress causes exacerbations, according to the National MS Society (Artemiadis, 2011).


Treatment for a relapse often include high doses of corticosteroids (IV Solumedrol or oral prednisone). However, not all relapses require treatment as steroids simply help to shorten a relapse. If your movement isn't limited and you're not uncomfortable, your doctor might recommend waiting until symptoms improve on their own. Patients for whom steroids are not effective may use H.P. Acthar Gel or undergo plasmapheresis (plasma exchange) to stop a relapse.

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Artemiadis AK, Anagnostouli MC, Alexopoulos EC. Stress as a Risk Factor for Multiple Sclerosis Onset or Relapse: A Systematic Review. Neuroepidemiology. 2011;36(2):109-20. doi: 10.1159/000323953. Epub 2011 Feb 17.  Accessed at