Find care now
If you are experiencing a medical emergency, please call 911 or seek care at an emergency room.
When the influenza virus invades the body, the immune system responds with inflammation. Some of the flu’s classic symptoms, like fever, are a result of this response. For people with controlled multiple sclerosis (MS), inflammation can cause symptoms to temporarily flare in what’s known as a pseudo relapse.
Most MS medications suppress the immune system, so contagious respiratory viruses such as the flu and COVID-19 can be more severe in people who are taking these treatments. I advise my patients to take common sense steps against getting sick, such as getting vaccinated against both flu and COVID.
Based on this year’s flu season in the southern hemisphere, the U.S. Centers for Disease Control and Prevention predicts an average severity in 2024-2025. Between 2010 and 2023, at least 9 million and as many as 41 million people have contracted the flu each year.
If you are one of the approximately 1 million people in the U.S. diagnosed with multiple sclerosis, there are steps you can take to reduce exposure to the flu and limit your chances of a severe infection this season.
Multiple sclerosis & inflammation.
MS is a chronic immune disease in which inflammation impacts the brain, spinal cord, and/or optic nerve. Areas of inflammation and damage to these important parts of the nervous system are called lesions, and can lead to a wide range of neurologic symptoms, including:
-
Balance issues
-
Difficulty controlling the bladder
-
Dizziness
-
Muscle weakness or stiffness
-
Tingling, numbness, or pain
-
Vision problems
In patients with MS, new inflammation or changes to the body’s stable internal environment can cause symptoms to return or worsen without new lesions. This is called a pseudo relapse.
For example, sometimes being outdoors on a hot day can raise the body’s internal temperature enough for MS symptoms to flare up temporarily. When the core temperature returns to normal, the symptoms go away.
The same thing can happen when any type of inflammation occurs, including when the immune system is fighting off a virus like the flu.
Related reading: Multiple Sclerosis Early Intervention Can Mean a Bright Future
The body’s immune response to flu.
The body’s natural immune response to viral infection like influenza is complex. The immune system releases chemicals that trigger the production of virus-fighting antibodies and other cells. This can trigger inflammation, raise the body’s temperature, and cause other changes that can influence MS symptoms.
Many of the classic symptoms of influenza, such as a runny nose, coughing, fever, and muscle aches, are a result of the body working to fight the infection. If you also have a fever, chills, and body aches, be sure to rest and get plenty of fluids. It’s worth a call to your doctor to check in. We can discuss any MS symptoms you may have and prescribe an antiviral medication if necessary.
Related reading: Cold and Flu Season: 3 Reasons Why You Might Get Sick When It’s Cold Outside.
Flu prevention: Get a vaccine every year.
Medications to treat MS often work by suppressing the immune system to short-circuit symptom-producing inflammation. This leaves patients at greater risk for more severe symptoms from a viral infection like influenza.
I advise my patients to get the latest flu vaccine (and COVID, too) each year to reduce their risk of a serious viral infection. Vaccines can cause a temporary pseudo relapse of symptoms. But these flares last only up to 12 hours instead of a week or more with a flu infection.
Other precautions are similar to those we would recommend for people who don’t have MS. Wash your hands often, and wear a mask if you’re around someone who has symptoms of a respiratory infection.
There is no evidence that getting vaccinated against the flu will cause MS symptoms to worsen in the long run. But the risk of flu is real for people with suppressed immune system. Taking steps to avoid illness will protect your health this flu season and in the long term.
