An acute exacerbation of MS is also known as an MS relapse or MS attack. It’s defined as a new or worsening set of neurologic symptoms that last more than 24 hours in a person who lives with relapsing MS. This is caused by an immune-related injury to the brain or spinal cord. When such an injury occurs, new symptoms typically develop over hours or days. Symptoms might include numbness or tingling, weakness or difficulty with coordination, changes in vision, and changes in bladder or bowel function.

But not all exacerbations are due to an MS relapse. Common stresses on the body, such as infections — including upper respiratory, gastrointestinal, urinary tract infections — and elevated body temperature, can unmask symptoms due to a prior neurologic injury. This is considered a “pseudo-relapse.” A pseudo-relapse doesn’t require the same treatment as an MS attack. This is a complex issue. The distinction between a relapse and a pseudo-relapse should be made by your neurologist.

If you’re experiencing new neurologic symptoms, contact your neurologist or primary care doctor right away. Depending on the severity of your symptoms, you might need to go to the hospital. At the hospital, you can get an MRI scan and other diagnostic tests right away.

In general, you should go to the hospital if you have new significant physical disability. For example, you should go to the hospital if you suddenly can’t see, walk, or use your limbs. If you go to the hospital, you might be admitted for a few days. You might also be allowed to go home if your symptoms improve. If you don’t have significant disability, you can get diagnostic testing as an outpatient, provided that you are closely monitored by your doctor.

The main treatment for a new MS relapse is corticosteroids. The goal of therapy is to minimize injuries caused by inflammation and reduce the recovery time. The typical treatment includes 3 to 5 days of high-dose “pulse” corticosteroids. This treatment can be given intravenously or orally. It’s usually followed by 3 to 4 weeks of “tapering” with oral medication. This involves taking progressively lower doses of the medication until the treatment is completed.

High-dose intravenous steroids can be given in the hospital or at an outpatient infusion center. High-dose oral steroids are just as effective and can be taken at home, but involve taking up to 20 pills daily.

Some people have acute, severe neurologic symptoms due to MS but respond poorly to corticosteroids. They usually need to be hospitalized, and they might receive a treatment called “plasma exchange” for 3 to 5 days. It involves filtering the blood to remove potentially harmful antibodies. Treatment with plasma exchange isn’t used for most people with MS.

Side effects of high-dose corticosteroids might include mood changes, upset stomach, insomnia, and risk for infections. Abnormalities on laboratory testing are another possible side effect, and could include having elevated blood glucose and white blood cell count.

While being treated with corticosteroids, you might also be prescribed medications for gastric protection, to help with sleep, and to prevent infections.

Short-term treatment with high-dose steroids carries a low risk of lasting health issues. However, chronic treatment increases the risk for several conditions including infections, decreased bone mineral density, prediabetes, and metabolic syndrome. This highlights the importance of using steroid-sparing therapies, also known as disease-modifying therapies (DMTs), to prevent MS relapses.

In addition, people with diabetes who receive treatment with high-dose corticosteroids may need to be monitored in the hospital for possible complications.

Without treatment, symptoms due to an MS relapse generally improve over weeks to months in people with relapsing multiple sclerosis. However, the recovery might be less complete and take longer. Speak with your neurologist about the benefits and risks of treatment.

Treatment with high-dose corticosteroids reduces active injury due to MS within hours to days. If your symptoms are caused by an MS relapse, they should stabilize within days. Your symptoms should continue to improve over weeks or months. If this is not the case, speak with your doctor to discuss next steps, which might include additional testing and treatment.

If you experience an MS relapse within six months of starting a new disease-modifying therapy, this might be because the therapy has not yet achieved full efficacy. This isn’t considered a treatment failure.

However, if you experience two or more confirmed MS relapses in one year, or have an attack that causes significant disability while on therapy, you should revisit your treatment plan with your neurologist.

Yes. Depending on the type and severity of your symptoms, you might receive additional treatments. This could include physical therapy, occupational therapy, or speech therapy. It might also include medications that help with specific symptoms, such as neuropathic pain, muscle spasms, bowel and bladder symptoms, and fatigue. These treatments are personalized to your symptoms and tapered as your symptoms improve.

Most people who experience an MS relapse don’t need to go to an inpatient rehabilitation program, unless there is significant physical disability. For example, if a person experienced an MS relapse and could no longer walk due to a spinal cord injury, they would need to go to a rehabilitation program.

For most people, a rehabilitation program isn’t necessary after an MS relapse. If needed, physical therapy can be done on an outpatient basis several times per week, and tapered as your symptoms improve.

Xiaoming (Sherman) Jia, MD, MEng is a graduate of Massachusetts Institute of Technology and Harvard Medical School. Dr. Jia trained in internal medicine at Beth Israel Deaconess Medical Center and in neurology at the University of California San Francisco. In addition to specializing in treatment of patients with multiple sclerosis, Dr. Jia conducts research on the genetics of neurologic disorders. He led one of the first studies to identify genetic factors that influence a progressive disease course in MS. His early work focused on understanding the genetics of the human immune system, and significantly advanced understanding of immune-mediated disorders including MS, rheumatoid arthritis, and HIV-1 infection. Dr. Jia is a recipient of the HHMI Medical Fellowship, the NINDS R25 award, and the UCSF CTSI Fellowship. Aside from being a neurologist and statistical geneticist, he is a lifelong violinist and served as Concertmaster of the Longwood Symphony, an orchestra of medical professionals in Boston, MA.