Understanding Multiple Sclerosis (MS) Relapses

Symptoms aren't always a sign of disease progression

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In people with multiple sclerosis (MS), a relapse is either the worsening of symptoms you already have or the appearance of new symptoms. It's typically confirmed by the development of a lesion on your brain or spinal cord and is considered a sign that your disease is progressing.

In the course of managing your disease, it can often be difficult to know if you're experiencing true symptoms of MS or if you're simply having an "off day." At other times, you may begin to wonder if a sudden flare-up is incidental or if it's a sign that your MS is worsening. Not knowing can make matters worse, adding anxiety and depression to the long list of possible symptoms.

Am I Having A Multiple Sclerosis Relapse?
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Also referred to as exacerbations, attacks, bouts, or flares, MS relapses are caused by inflammation in the central nervous system, which further damages the protective coating that insulates nerves, known as the myelin sheath. When this protective layer is stripped away, a lesion (an area of inflammation) and eventual damage (demyelination) occur, making the nerves less efficient in conducting signals.


In the most common course of the disease, referred to as relapsing-remitting MS (RRMS), a period of acute symptoms will be followed by a period of remission during which time any inflammation will gradually subside and end. However, this doesn't mean that all symptoms will disappear. In some cases, the symptoms will persist even during remission, albeit at a relatively steady level with only occasional ups and downs.

When you have a relapse, your symptoms depend on the location of the new lesion in the brain, spinal cord, or optic nerve. Some relapses are very obvious; for instance, losing your sight in one eye due to inflammation of the optic nerves. However, other relapses may not be as sudden or dramatic; for instance, inflammation in the cerebellum may just make you feel extra “wobbly” or tired.

Relapse Criteria

In strict medical terms, an MS relapse occurs when you experience either one or more new neurological symptoms OR the worsening of one or more old symptoms for at least 24 hours. In addition, the current attack must be separated from a prior attack by at least 30 days.

When Symptoms Aren't Due to a Relapse

Not all flare-ups mean that your disease is progressing. For example, a pseudoexacerbation, or pseudo-relapse, is the temporary worsening of symptoms caused by external factors.

Most often, these are caused by an increase in core body temperature due to heat from hot weather, exertion, or fever, known as the Uhthoff's phenomenon. Once your body temperature returns to normal, the neurological symptoms subside. Infections and physical or emotional stress are also common causes of pseudo exacerbations.

The same applies to paroxysmal symptoms of MS. These are the symptoms that appear suddenly, last for a few seconds or minutes, and then disappear just as quickly. Paroxysmal symptoms may occur as a one-off event or repeat in cycles over the course of hours or days. In some cases, the recurrent symptoms may take months to fully resolve.

But even recurrent symptoms like these don't constitute a relapse. They don't so much occur because of a progression of the disease but rather because of the existing nerve injury.


Knowing the difference between a relapse, a pseudoexacerbation, and a paroxysmal symptom is not an easy distinction to make. Like the disease itself, the symptoms of MS are often erratic and unpredictable. Even with the relapse criteria mentioned above, healthcare providers sometimes have a hard time distinguishing the difference.

The only way to really know if you're having a relapse is to have a magnetic resonance imaging (MRI) scan with gadolinium. This contrast material, which is injected during the scan, is drawn to areas of inflammation and “lights up” when a lesion is “active.” In this case, demyelination is currently occurring and you are having a true relapse, rather than feeling symptoms caused by older lesions.

It's not always necessary to have an MRI. Depending on what you're experiencing, your healthcare provider may simply want to know if the symptoms are interfering with your ability to function and/or your quality of life. It's a subjective assessment but one that's central to the management of your disease and your long-term well-being.


Many relapse symptoms can be treated with high-dose corticosteroids, usually Solu-Medrol (methylprednisolone). Your healthcare provider will decide how to treat a relapse by weighing how much disability the symptoms are causing and how much they interfere with your daily activities against the potential side effects and complications treatment can cause.

The steroid treatment may significantly shorten the duration of your more severe symptoms, allowing a faster return to normal activities. However, some symptoms may take a longer time to go away and may never quite clear up entirely, which means you may have some residual disability.

Even if there is evidence of relapse, your healthcare provider may still not recommend treatment. Fatigue or mild sensory changes that don’t impact your life can often be left to resolve on their own. Be vocal in conversations with your practitioner to paint a complete picture of how you are feeling. You can use our Doctor Discussion Guide below to help you start that conversation.

Multiple Sclerosis Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Woman


The most important thing that you can do to prevent relapses is to begin using and adhering to one of the disease-modifying therapies. These medications have been shown to reduce the number and severity of MS relapses, the development of new brain and spinal cord lesions, and delay your disability progression.

The good news is that there are a number of options available now for treating MS, so together with your neurologist, you can find the best fit for you.

A Word From Verywell

MS relapses can be incredibly frustrating and anxiety-provoking for both patients and their loved ones, and it's common to question whether you're truly experiencing a new relapse, feeling symptoms from old relapses, or having a pseudoexacerbation. While it's wise to be watchful of your condition, don't let MS take over your life by worrying if every symptom is a sign of relapse. Instead, try to maintain a healthy lifestyle with plenty of rest while adhering to any treatment you may be prescribed.

If there are symptoms you can't explain, try first to avoid any triggers that may have caused them and see if that helps. If it doesn't, try not to panic or assume the worst. Go see your healthcare provider and take the situation one step at a time.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Tauil CB, Grippe TC, Dias RM. Suicidal ideation, anxiety, and depression in patients with multiple sclerosisArquivos de Neuro-Psiquiatria. 2018;76(5):296-301. doi:10.1590/0004-282x20180036

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  4. Gallego-Gallego M, Anillo-Lombana VE, Gómez-Mayordomo V, García-Miguel FJ. Uhthoffʼs phenomenon in a patient with multiple sclerosis during the perioperative period for hip surgery. Case report. Colombian Journal of Anesthesiology. 2018:1. doi:10.1097/cj9.0000000000000078

  5. Yates TJ, Crawley F. Paroxysmal symptoms in multiple sclerosis masquerading as transient ischaemic attacksBMJ Case Rep. 2010;2010:bcr0320102831. Published 2010 Jul 23. doi:10.1136/bcr.03.2010.2831

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Additional Reading
  • Birnbaum G. Multiple Sclerosis: Clinician’s Guide to Diagnosis and Treatment. 2nd ed. New York, NY: Oxford University Press.

  • National Multiple Sclerosis Society. Disease-Modifying Therapies for MS. https://www.nationalmssociety.org/NationalMSSociety/media/MSNationalFiles/Brochures/Brochure-MS-Disease-Modifying-Medications.pdf.

By Julie Stachowiak, PhD
Julie Stachowiak, PhD, is the author of the Multiple Sclerosis Manifesto, the winner of the 2009 ForeWord Book of the Year Award, Health Category.