• A multiple sclerosis (MS) relapse — also called a flare-up — involves new or worsening symptoms that last more than 24 hours and aren’t caused by a fever, infection, or overheating.
• Having an MS flare-up while taking disease-modifying treatment may be a sign that your MS is becoming more active.
• Symptoms of MS flares may vary widely. Mild symptoms may resolve on their own, while more severe symptoms may require hospitalization.

Multiple sclerosis damages the myelin sheath that coats neurons (nerve cells) within the brain and spinal cord, collectively known as the central nervous system. This damage can cause symptoms such as vision problems, weakness, numbness, imbalance, spasticity, and bowel or bladder dysfunction. As MS progresses, its symptoms and their severity can fluctuate based on several factors.

Symptom fluctuations may or may not be an MS relapse. MyMSTeam sat down with Dr. Jacqueline Nicholas to find out more about MS relapses — what causes them and how to manage them. Dr. Nicholas is a board-certified neurologist specializing in neuroimmunology, MS, and spasticity. She currently serves as the system chief of neuroimmunology and multiple sclerosis, the director of MS research, and the neuroimmunology fellowship director at the OhioHealth Multiple Sclerosis Clinic in Columbus, Ohio.

What Is a Relapse?

Relapses are often referred to as attacks, exacerbations, or flares. Most people living with MS will experience a relapse at some point. However, a relapse is not the same thing as the standard progression of MS. According to Dr. Nicholas, “When we use the term progression, we usually think of something that is slowly worsening over a long period of time, separate from relapses.”

An exacerbation is a worsening of MS symptoms or the onset of new MS symptoms that last more than 24 hours and are not due to fever, infection, or overheating. Symptoms of a relapse typically develop over hours to days.

Symptoms of a relapse vary from person to person. No two exacerbations are alike. How often and how severe relapses will be is unpredictable. One MyMSTeam member described their MS flare-up: “I will not be able to sleep for a few nights. I get very cold when normally I am always hot. My stiffness in my legs and back start getting bad. It will feel like I am getting the flu. Then it gets worse, and I have trouble with balance and sometimes can't walk.”

A true MS exacerbation will have these characteristics:

• The flare must include new symptoms or a worsening of old symptoms.
• The attack must last at least 24 hours.
• The episode cannot occur within 30 days of the last flare-up.
• There cannot be another cause for the exacerbation, such as an infection, fever, or temperature extremes (usually hot weather).

What Causes MS Flare-Ups?

Relapses are caused by inflammation which results in damage to the myelin coating on neurons within the brain or spinal cord. Most exacerbations occur for a few days at a time. Recovery from a relapse can be complete, partial, or without any improvement. Most people recover from a relapse within two to three months of onset. In general, the full degree to which an individual will recover from a single relapse may take up to one year. That’s not to say that there won’t be improvement sooner, but the majority of the improvement would occur within one year.

Common symptoms of an MS flare include fatigue, dizziness, balance and coordination issues, weakness in a leg or arm, muscle spasms, difficulties remembering and concentrating, and areas of numbness, pain, or tingling. Vision issues, particularly optic neuritis, may also point to an MS flare. “Optic neuritis is a common relapse symptom in the setting of MS,” Dr. Nicholas explained.

What Is a Pseudo-Relapse?

A pseudo-relapse or pseudo-exacerbation is a temporary worsening of prior or chronic symptoms. It can seem like a relapse, but it isn’t. A pseudo-relapse is not caused by an uptick in disease activity. In other words, it is not accompanied by inflammation or new brain or spinal cord damage.

A pseudo-exacerbation is usually caused by an external factor, such as excessive heat or stress. A pseudo-flare can also be caused by an infection, such as a urinary tract infection (UTI), or a cold or flu. The most common cause of pseudo-relapse is UTI. For this reason, when doctors are evaluating people with MS for a possible relapse, they often screen for a UTI.

To differentiate between a relapse and a pseudo-relapse, it's important to determine whether or not the person has a fever. Even a mild infection or the smallest body temperature increase can trigger symptoms.

“When I am tired, hot, or stressed, I will have a pseudo-flare,” said a MyMSTeam member. “Once I am cool, calm, and collected, my symptoms go away.” Most pseudo-flares resolve within 24 hours after the underlying cause of the exacerbation is resolved.

Why Do Relapses Occur?

Exacerbations are caused by inflammation in the central nervous system. Inflammation damages the myelin on neurons within the brain and spinal cord, also known as demyelination. Demyelination and inflammation interrupt the flow of signals traveling along neurons. The location of inflammation or damage determines which symptoms of MS develop. Sometimes, inflammation may cause no symptoms at all. This is why health care professionals recommended individuals with MS be monitored for silent disease activity with magnetic resonance imaging (MRI) scans.

One can experience just one symptom or many symptoms together during a relapse. When the inflammation impacts a single area of the central nervous system, relapses typically produce only one neurologic symptom — for example, numbness in one leg. Other times relapses cause a person to experience several symptoms simultaneously — for instance, muscle weakness and vision changes. This usually happens when the inflammation occurs in more than one part of the brain or spinal cord.

What Do Relapses Indicate?

No evidence of disease activity (NEDA) is an emerging goal of MS treatment. Breakthrough flares (flares that occur during treatment with a disease-modifying therapy) can be an indication that a person's disease is becoming more active. A breakthrough flare may indicate that it’s time to consider starting or switching to a new MS treatment. But not all relapses mean a treatment regimen has stopped working.

Drug therapies for MS need time to take effect. “If somebody just started treatment maybe a month ago and they had a relapse, it's possible that that treatment just hasn't had enough time to get into the system and have its full effect,” explained Dr. Nicholas. “With each disease-modifying therapy, for the most part, they take about six months to give their full benefit.”

The good news is that there are multiple treatment options available to prevent new relapses and new lesions in MS. “Typically, we would pick something that we believe, in our experience and based on clinical trials, is more effective than the one that the individual had a breakthrough on,” said Dr. Nicholas.

Take the quiz: Is My MS Progressing?

What Types of MS Feature Relapses?

In relapsing-remitting multiple sclerosis (RRMS), relapses can occur throughout the span of the disease. Remission is a confusing term because in some conditions, such as cancers, remission typically refers to the absence of disease. Even when MS is considered to be in a phase of remission — not in an active relapse — MS can still cause silent damage in the brain and spine. These bouts of relapse and remission can last days, weeks, or months. Approximately 85 percent of people with MS are diagnosed with RRMS, the most common form of MS.

In RRMS, the time between relapse and remission varies. One study found people with RRMS had a relapse on average once every two years. Sometimes they’re more frequent; in other cases, less frequent. Generally speaking, exacerbations tend to happen more often during the years right after diagnosis, but people with MS can experience a relapse at any time.

“One way to significantly reduce the chance of having an MS relapse is to take a disease-modifying therapy (DMT) for multiple sclerosis,” said Dr. Nicholas. “There are many options which are proven to reduce the risk of relapse.”

People with secondary progressive multiple sclerosis (SPMS) can experience relapses, but much less frequently. People diagnosed with primary progressive multiple sclerosis (PPMS) often experience fluctuations in how they feel from one day to the next, but by definition, they do not experience relapses.

Dr. Nicholas explained, “There are rare individuals who've been believed to have primary progressive MS who then can have a subsequent relapse. We call that progressive-relapsing MS.”

Learn more about how disability is tracked in EDSS: Tracking MS Progression.

Treating Relapses

Relapses that don’t severely impact a person’s ability to comfortably perform daily activities may self-correct without medical intervention. Mild sensory changes or periods of tiredness may resolve on their own.

“I determine whether to give steroids for a relapse based on how severe the relapses are and after a careful discussion with my patient,” said Dr. Nicholas. “If I see an individual who is having a small area of new numbness consistent with a new relapse, but it is not bothersome, we do not have to treat that individual with steroids. However, if somebody comes into my office and they can't walk because of their relapse, I would strongly recommend steroid treatment and potentially plasmapheresis, if there is no or minimal benefit with steroids. This type of relapse is severe, and the goal would be to speed up recovery quickly.”

Pharmaceutical Options

A short course of corticosteroids, such as Solu-Medrol (methylprednisolone), dexamethasone, or prednisone, can speed up recovery from a relapse. “The most classic treatment would be [intravenous] steroids like methylprednisolone for between three to five days,” advised Dr. Nicholas.

If a person doesn't tolerate steroids well or doesn’t like the side effects, another injectable option is Acthar gel — purified adrenocorticotropic hormone. Acthar gel is extended-release and provides therapeutic benefits after it's injected.

“Steroids have always helped me in the past whenever I had a flare-up,” shared a MyMSTeam member. “When I knew I was going to be on steroids, I would change my diet for three months following treatment, so as not to put on the extra weight.”

Recovering After a Flare-Up

Recovery from a relapse usually happens in the first two to three months after the flare. However, in some cases, healing may continue for up to 12 months.

Sometimes, a person’s relapse may be so severe as to warrant hospitalization and post-discharge rehabilitation. Depending on how an exacerbation affects a person, various health care professionals may be involved in recovery, including physical therapists, occupational therapists, and speech therapists.

Mental health is also important in recovering from a flare. “Make sure that mental health and emotional health is addressed,” Dr. Nicholas emphasized. “If somebody feels overly stressed, that can be really bad for the immune system and can be very harmful. In addition, stress can lead to an increase in chronic symptoms.”

Whether or not your flares are significant enough to warrant a trip to the doctor, you should report them to your health care provider. Relapses are a sign that your MS could be becoming more active. Only a qualified medical professional can tell for sure.

Talk With Others Who Understand

On MyMSTeam, the social network for people with multiple sclerosis and their loved ones, more than 170,000 members come together to ask questions, give advice, and share their stories with those who understand life with MS.

How do you manage your MS relapses? Have you ever had a pseudo-relapse? Share your story in the comments below, or start a conversation with others on MyMSTeam.