Many people with multiple sclerosis (MS) experience periods of new or worsening symptoms. These episodes are known as flare-ups, relapses, or exacerbations. Most people with MS are diagnosed with relapsing types of MS (including relapsing-remitting MS, or RRMS), which can all involve flares.

During a flare, you may experience new MS symptoms or have old symptoms return. Symptoms may last anywhere from a couple of days to several months. There’s no specific list of symptoms that doctors use to diagnose a flare — these episodes look different from person to person.

Flares may also vary each time you have them. New flares may involve different symptoms compared to old flares. Additionally, some flares only cause minor issues, but severe relapses can drastically affect your health or require emergency care.

Read more about how long MS relapses last.

How Do You Know if It’s a Flare?

You’re not necessarily having a flare-up every time you feel a little worse than usual. You could be experiencing health problems caused by other factors, or your MS symptoms may periodically improve and worsen without technically being a flare. Neurologists consider a flare to have these characteristics:

• Your symptoms last for 24 hours or more.
• Your symptoms can’t be explained by another factor, including fever or infection.
• Your condition was stable for 30 days or more before your symptoms worsened.

If your new or worsening symptoms don’t meet these criteria, you may be having a pseudoexacerbation. Pseudoexacerbations aren’t caused by new damage to the central nervous system. They’re associated with other influences, such as hot weather, stress, or an infection — most frequently a urinary tract infection.

Below are some possible symptoms that may arise when you’re having a flare. However, keep in mind that your flares may not include all — or even any — of these symptoms. You may also experience other health issues that aren’t on this list. Talk to your health care provider if you’re not sure whether you are experiencing a flare and need help managing relapses.

1. Fatigue

Tiredness is one of the most common symptoms of a flare. You may also experience weakness or malaise (a general overall feeling of sickness).

During a flare, fatigue may be caused by cytokines, which are substances produced by the immune system. In addition to causing certain symptoms of MS attacks, cytokines may slow the speed at which your nerves convey messages.

A flare that consists primarily of fatigue may not need any treatment — your energy levels should eventually return to normal. However, talk to your doctor if you’re so tired that you can’t carry out your usual activities.

2. Pain

Pain is another common symptom during MS flares. The many types of pain you may experience include:

• Cramping
• Headaches
• Facial pain
• Back pain
• Burning pain in your feet or hands
• Muscle aches
• A squeezing feeling around your midsection

Pain may occur as nerve cells in your brain, spinal cord, or other parts of your body are damaged. MS can also cause tightening or stiffening of muscles, which may lead to pain.

Medications, medical devices, massage, acupuncture, and yoga may help reduce pain. Physical therapy or occupational therapy may also help prevent new symptoms of pain.

3. Unusual Sensations

MS flares can lead to several unusual or uncomfortable sensations, such as:

• Numbness
• Tingling
• Pins and needles
• Itching
• Electric shocks
• Restless legs syndrome (a condition that makes you feel like you have to move your legs)

Your nerves are responsible for noticing various sensations and communicating these feelings to the brain. When MS damages the nerves, these unusual sensations can be the result.

Mild sensations may not need treatment. The sensations will generally improve after a short time. However, you should talk to your doctor if these feelings are severe or ongoing.

4. Balance Problems

You may feel dizzy, lightheaded, or uncoordinated during an MS exacerbation. It may be harder than usual to walk. You may also experience vertigo (feeling like everything is spinning around you). These changes occur when the parts of your nervous system that control balance become damaged by MS.

Balance problems may make it unsafe for you to walk or take part in your usual activities. Tell your doctor about this symptom so that it can be treated right away.

5. Muscle Tightness and Weakness

Trouble walking or moving may also come as a result of spasticity — stiffness or uncontrolled muscle movement. You may have a hard time bending or straightening your joints.

Severe spasticity can be painful. In people with MS, this symptom most often occurs in the leg muscles. Weakness can also be an issue and affect your legs or your arms.

6. Problems With Thinking

An MS relapse may leave your mind in a fog. You may have a hard time:

• Thinking clearly
• Concentrating
• Remembering
• Learning
• Planning or organizing
• Talking or listening

Known as cognitive symptoms, these symptoms affect more than half of people with MS. Tell your doctor if you’re experiencing changes in the way your mind works. Your health care team can help evaluate problems and may recommend cognitive rehabilitation or other strategies to help you improve and cope.

7. Changes in Bladder or Bowel Habits

Many people with MS need to urinate frequently, experience constipation or diarrhea, or have a hard time holding in stool or urine. These problems, which can get worse during a flare, may develop due to problems with the parts of the spinal cord that help control the bladder or intestines.

Bladder or bowel problems may hold you back and keep you from living your life to the fullest. Your doctor can help you come up with treatment options — which may include medication, medical devices, diet changes, pelvic floor therapy, surgery, or lifestyle changes — to help you avoid these issues in the future.

8. Vision Changes

You may have a hard time seeing clearly during an MS flare-up. About 7 out of 10 people with MS experience vision problems at some point. These issues include blurred vision, double vision, a blind spot, difficulty seeing colors, unusual eye movements, or blindness.

Eye problems during MS may occur as a result of inflammation of the optic nerve (the nerve fiber that carries signals from the eyes to the brain) or because of weak or stiff muscles around the eye.

Vision problems can be serious. If you’re having new or worsening vision problems, tell your doctor right away. Medications such as corticosteroids can help treat vision loss and other symptoms of a flare.

MS Treatments Can Reduce the Rate of Relapses

Disease-modifying therapies (DMTs) were approved to treat MS based on their proven effectiveness in reducing the rate of relapse and slowing disease progression. If you’ve been taking your prescribed DMT on schedule, as directed, and you’re still having multiple sclerosis relapses, it may be time to talk to your doctor about your MS treatment plan.

Talk With Others Who Understand

MyMSTeam is the social network for people with multiple sclerosis and their loved ones. On MyMSTeam, more than 205,000 members come together to ask questions, give advice, and share their stories with others who understand life with multiple sclerosis.

Can you always tell when an MS flare is starting? Have you had similar or different symptoms with each flare? Share your experience in the comments below, or start a conversation by posting on your Activities page.