Relapsing-remitting multiple sclerosis represents the most common pattern of multiple sclerosis, affecting around 85% of people diagnosed with this complex neurological condition. Understanding how symptoms come and go, what triggers flare-ups, and how modern medicine approaches management can help patients and their families navigate the challenges of living with this lifelong disease.

Understanding Relapsing-Remitting Multiple Sclerosis

Relapsing-remitting multiple sclerosis, often abbreviated as RRMS, is a specific type of multiple sclerosis, which is an autoimmune condition that affects the central nervous system (the brain and spinal cord). The name itself describes the pattern of symptoms that people with this condition experience. During a relapse—also called an attack, flare-up, or exacerbation—symptoms appear suddenly or existing symptoms become significantly worse. These episodes are followed by periods of remission, when symptoms partially or completely disappear, and the disease doesn’t actively get worse.^[1][2]

What makes RRMS distinct from other types of multiple sclerosis is this alternating pattern. People with this condition might feel relatively well for months or even years between relapses. During these quiet periods, they may have no symptoms at all, or their symptoms remain stable and manageable. However, when a relapse strikes, it can bring new symptoms or make old ones return with greater intensity.^[2]

The relapses themselves typically develop quickly, usually over a few hours or days, and can last anywhere from 24 hours to several weeks or even months. After each relapse, the body attempts to repair the damage, which is why symptoms often improve during remission. However, this repair process isn’t perfect—it creates scar tissue on the nervous system, which is where the term “sclerosis” comes from (meaning scarring). Over time, this accumulated damage can lead to lasting effects.^[1][4]

How Common Is This Condition

Relapsing-remitting multiple sclerosis is not a rare condition. In the United States alone, approximately 1 million people are living with multiple sclerosis, and an estimated 80% to 85% of those diagnosed with MS have the relapsing-remitting type, making it by far the most common form of the disease.^[1][4]

Multiple sclerosis most often develops in people during their 20s and 30s, though it can occur at other ages. Women are twice as likely to develop MS compared to men. This gender difference is consistent across different populations and geographical regions, though researchers are still working to understand exactly why women are more susceptible to the condition.^[3]

Around the world, MS affects approximately 2.1 million individuals every year. The disease creates a significant economic burden on healthcare systems, with direct and indirect costs ranging from $8,528 to $52,244 per patient per year in the United States. These costs reflect not only medical treatments but also the impact on a person’s ability to work and maintain their normal activities.^[9]

What Causes Relapsing-Remitting Multiple Sclerosis

The exact cause of multiple sclerosis remains unknown, which can be frustrating for people seeking clear answers. However, research has revealed important clues about what contributes to the development of this condition. Scientists believe that MS develops when a combination of genetic and environmental factors come together in a particular person.^[1]

When someone has multiple sclerosis, their immune system makes a critical mistake. Instead of only attacking harmful invaders like bacteria and viruses, it mistakenly attacks healthy parts of the central nervous system. Specifically, the immune system targets myelin, which is a protective fatty layer that surrounds nerve fibers in the brain and spinal cord. You can think of myelin like the insulation around electrical wires—it helps nerve signals travel quickly and efficiently.^[1][6]

When the immune system damages this protective myelin sheath, the nerve fibers underneath can also become damaged. This damage disrupts the messages that the brain sends through the nervous system to different parts of the body. During a relapse, inflammation attacks the myelin, creating new areas of damage. The damaged areas form scar tissue called lesions, which give the disease its name—multiple sclerosis means “many scars.”^[3]

Genetics play a role in determining who develops MS, but it’s only a small part of the picture. Research suggests that certain changes in DNA can make someone more susceptible to developing an autoimmune condition like MS. However, the risk of passing the condition to children is relatively low. MS is not directly inherited like some genetic diseases, but having a family member with MS does slightly increase a person’s risk.^[1]

Environmental factors also contribute to disease development. Scientists think that certain infections might trigger MS in people who are genetically susceptible. The Epstein-Barr virus, which causes infectious mononucleosis (sometimes called “mono”), has been particularly linked to MS risk. Other environmental factors that research has identified include vitamin D deficiency and exposure to certain bacteria or viruses during childhood.^[1][3]

Who Is at Higher Risk

While anyone can develop relapsing-remitting multiple sclerosis, certain groups of people face higher risks. Understanding these risk factors doesn’t mean that someone will definitely develop the condition, but it helps identify who might benefit from paying closer attention to early warning signs.

Gender plays a significant role, with women being approximately twice as likely as men to develop MS. The disease also tends to affect people during their most productive years, typically striking individuals in their 20s and 30s. This timing can significantly impact education, career development, family planning, and other major life events.^[3]

Geography and ethnicity also influence MS risk. The condition is more common in people of European descent and in those living farther from the equator. Scientists aren’t entirely sure why this pattern exists, but it may relate to differences in sunlight exposure and vitamin D production, along with genetic factors that vary among different populations.^[3]

Cigarette smoking appears to increase the risk of developing MS and may also make the disease more active once it develops. People who smoke tobacco products face a higher chance of both getting MS and experiencing more severe symptoms. This makes smoking cessation an important consideration for anyone at risk or already diagnosed with the condition.^[3]

Having other autoimmune conditions or a family history of autoimmune diseases can also increase risk. While MS itself isn’t strongly inherited, the general tendency toward autoimmune problems can run in families. If a close relative has MS or another autoimmune condition, the risk increases slightly, though most people with these family connections never develop MS.^[1]

Common Symptoms of RRMS

The symptoms of relapsing-remitting multiple sclerosis vary tremendously from person to person. No two individuals experience the condition in exactly the same way, which can make it challenging to recognize initially. The specific symptoms someone experiences depend on which areas of the brain or spinal cord are affected by the immune system’s attack.^[1]

Vision problems are often among the earliest symptoms of RRMS. These can include blurry vision, difficulty seeing colors correctly, painful eye movements, or seeing double. Some people experience inflammation of the optic nerve, called optic neuritis, which often starts with pain in the eye or headache on one side of the head. Vision problems can be particularly alarming, but many people find that these symptoms improve during remission.^[1][6]

Sensory symptoms are also extremely common. Many people with RRMS experience numbness, tingling, or unusual sensations in various parts of their body. These feelings often affect the hands, feet, arms, or legs. Some people describe a squeezing sensation around their chest or abdomen that feels like a tight hug. Another distinctive sensation that some people experience is an electrical tingling or shock-like feeling that runs down the back when bending the neck forward.^[1]

Fatigue represents one of the most challenging symptoms for many people with RRMS. This isn’t ordinary tiredness that improves with rest—it’s a profound exhaustion that can make even simple daily activities feel overwhelming. The fatigue associated with MS can affect a person’s ability to work, care for family members, or maintain social connections.^[1]

Movement and coordination problems frequently occur in RRMS. People may experience muscle weakness, particularly in the legs, making walking difficult. Muscle stiffness or spasticity can develop, where muscles feel tight and resistant to movement. Balance problems and lack of coordination can make activities like walking, climbing stairs, or even standing still more challenging. These symptoms can significantly impact independence and mobility.^[1][4]

Bladder and bowel problems affect many people with RRMS. These issues can include difficulty starting urination, a feeling of urgency (needing to go immediately), constipation, or loss of bladder or bowel control. While these symptoms can be embarrassing to discuss, they are common enough that healthcare providers are well-prepared to address them.^[1]

Cognitive difficulties, often described as “brain fog,” can affect memory, concentration, and the ability to think clearly. Some people find it harder to multitask, process information quickly, or remember details. These cognitive symptoms can impact work performance and daily decision-making, though they may be less visible to others than physical symptoms.^[1]

Depression and other mood changes occur frequently in people with RRMS. This can result from both the physical effects of the disease on the brain and the emotional challenge of living with a chronic, unpredictable condition. Sexual problems, including difficulty becoming aroused or reaching climax, can also develop and affect quality of life and relationships.^[3][4]

During a relapse, it’s common for people to experience a combination of these symptoms rather than just one isolated problem. For some fortunate individuals who have complete recovery during remission, symptoms may disappear entirely. For others, incomplete recovery means that some symptoms persist even between relapses, though these can usually be managed with appropriate treatments and therapies.^[1]

What Can Trigger or Worsen Symptoms

Many people with RRMS notice that certain situations or conditions in their environment can trigger relapses or temporarily worsen their symptoms. Understanding these triggers can help people take steps to avoid them when possible and recognize the difference between a true relapse and a temporary worsening of symptoms.

Heat sensitivity is remarkably common among people with MS. Increased body temperature—whether from hot weather, exercise, fever, or even a hot bath—can temporarily worsen symptoms. This phenomenon occurs because heat can slow down nerve signal transmission in damaged nerve fibers. Once the body cools down, symptoms typically improve. This temporary worsening due to heat is sometimes called a pseudo-exacerbation rather than a true relapse because no new damage is occurring.^[1][4]

Infections, even minor ones, can trigger MS symptoms to flare up. A urinary tract infection, sinus infection, or even a common cold can cause old MS symptoms to reappear or existing symptoms to intensify. This happens because infections activate the immune system, which can inadvertently increase inflammation in the central nervous system. Managing infections promptly becomes particularly important for people with RRMS.^[1]

Stress—whether physical or emotional—can worsen MS symptoms. Major life events, work pressures, family conflicts, or even the stress of managing the disease itself can contribute to symptom flares. While it’s impossible to eliminate all stress from life, learning stress management techniques can help minimize its impact on the disease.^[1][4]

Vitamin D deficiency has been linked to increased MS activity. People with lower levels of vitamin D in their blood may experience more frequent relapses and more active disease. While research continues to explore this connection, maintaining adequate vitamin D levels through diet, supplements, or careful sun exposure may help manage the condition.^[1][4]

Lack of sleep, poor diet, and tobacco use can all contribute to worsening symptoms. Sleep deprivation can intensify fatigue and cognitive problems. Poor nutrition may affect overall health and the body’s ability to repair damage. Smoking tobacco products not only increases the risk of developing MS but also appears to make the disease more active once present.^[4]

It’s important to understand that triggers can vary significantly from person to person. Something that causes problems for one individual with RRMS might not affect another person at all. Learning to recognize personal triggers often requires paying attention to patterns over time and keeping a symptom diary.^[1]

How to Reduce Your Risk and Stay Healthier

While there’s no guaranteed way to prevent multiple sclerosis, certain lifestyle choices and health measures may help reduce risk for those who haven’t developed the condition and potentially slow progression for those already diagnosed.

Avoiding tobacco products represents one of the most important steps anyone can take. Smoking increases the risk of developing MS, makes symptoms worse, and may speed up disease progression. For people already diagnosed with RRMS, quitting smoking can potentially improve outcomes and overall health. Support programs and smoking cessation aids can help people successfully quit.^[3]

Maintaining adequate vitamin D levels may offer some protection against MS. People who have higher levels of vitamin D in their blood appear to be at lower risk of developing the condition. Vitamin D can be obtained through diet (particularly fatty fish and fortified milk), supplements, and sensible sun exposure. However, people should consult with healthcare providers about appropriate vitamin D intake rather than self-treating.^[16]

Regular exercise appears to have multiple benefits for people with MS. Rather than making the disease worse, as doctors once feared, exercise actually strengthens muscles, eases fatigue, improves mood, and enhances quality of life. Some evidence suggests that strength training might even help slow damage in the brain. Exercise programs for people with MS typically include aerobic activities like walking or swimming for 150 minutes per week, along with daily stretching and twice-weekly strength training.^[16]

Following a balanced, healthy diet supports overall health and may influence MS activity. Research suggests that people with MS who eat plenty of fruits, vegetables, and whole grains experience less disability and fewer symptoms like depression and fatigue compared to those who eat less of these healthy foods. Limiting processed foods and animal fats while getting fats from healthier sources like fish, nuts, avocados, and olive oil may be beneficial. The Mediterranean diet, which is high in fish, vegetables, and nuts but low in red meat, has been shown to be neuroprotective.^[7][16]

Getting adequate, restful sleep helps the body repair and recover. Sleep problems can worsen MS fatigue and cognitive difficulties, so establishing good sleep habits becomes particularly important for people with this condition. This includes maintaining a regular sleep schedule, creating a comfortable sleep environment, and addressing any sleep disorders that may develop.^[16]

Staying current with vaccinations can help prevent infections that might trigger MS relapses. People with RRMS should work with their healthcare providers to ensure they receive appropriate vaccines, though some vaccines may need to be timed carefully depending on the treatments they’re receiving.^[16]

Managing other health conditions effectively also matters. Heart disease, diabetes, lung disease, and depression can all make MS progress more quickly. People with RRMS benefit from seeing their primary care doctor regularly to address any other health problems that develop. Taking care of overall health creates the best foundation for managing MS specifically.^[16]

What Happens in the Body During RRMS

Understanding what happens inside the body during relapsing-remitting multiple sclerosis helps explain why symptoms occur and why they follow the relapsing-remitting pattern.

In a healthy nervous system, nerve cells (neurons) send signals through the central nervous system to other parts of the body along nerve fibers called axons. These signals control everything from physical functions like balance and muscle coordination to cognitive abilities like memory and concentration. The myelin sheath that surrounds these axons allows signals to travel quickly and efficiently, much like insulation on electrical wires helps electricity flow properly.^[6]

During a relapse in RRMS, inflammatory immune cells called T cells mistakenly attack the myelin in the central nervous system. This inflammation damages the protective myelin sheath and can also harm the nerve fibers underneath. As the myelin breaks down, nerve signals slow down or get blocked entirely. This disruption in signal transmission causes the symptoms people experience during a relapse.^[6][9]

The damaged areas where myelin has been destroyed form lesions or scars in the brain and spinal cord. These lesions can be seen on MRI scans, which is why imaging tests play an important role in diagnosing and monitoring MS. Different locations of lesions cause different symptoms—for example, lesions in the optic nerve cause vision problems, while lesions in the spinal cord might cause weakness or numbness in the limbs.^[3]

During remission periods, the body attempts to repair the damaged myelin. Special cells try to rebuild the myelin sheath, which is why symptoms often improve after a relapse. However, this repair process isn’t perfect. The new myelin that forms is often thinner and less effective than the original, and scar tissue develops in the damaged areas. This is why some people don’t fully recover from each relapse and why accumulated damage over time can lead to lasting disability.^[4]

The inflammation that occurs during relapses also affects B cells, another type of immune cell. Modern research has revealed that B cells play a crucial role in MS, which is why some of the newest and most effective treatments work by targeting these cells. The interaction between T cells, B cells, and the cells that form myelin creates a complex cascade of events that researchers continue to study.^[13]

Over time, the accumulated damage from repeated relapses can lead to brain and spinal cord shrinkage as nerve cells die. Everyone loses some brain and spinal cord cells as they age, but in areas damaged by MS, cells die off faster than in healthy areas. This process typically happens very slowly over decades and usually shows up as gradual walking difficulty developing over several years.^[5]

Not all MS damage is accompanied by obvious symptoms. Particularly early in the disease, lesions can form without causing noticeable problems. These “silent” relapses can only be detected through MRI scans. If doctors perform MRIs regularly to look for new lesions at the beginning of the disease, they often find that lesions occur frequently. Only when a lesion develops in a critical area of the brain—like the optic nerve, spinal cord, or brainstem—where a lot of important functions are packed into a small space, does it cause a noticeable clinical relapse with accompanying symptoms.^[13]