Multiple sclerosis (MS) is often seen as a condition that mainly affects the central nervous system — the brain, spinal cord, and optic nerves. But think of it like a ripple effect in water: Its effects can spread beyond that. The immune system, for example, isn’t left untouched. MS is an immune-mediated disease that disrupts the nervous system. So, if you notice symptoms like swollen lymph nodes, you might wonder if MS could be stirring up more changes than you thought.

On MyMSTeam, members often discuss swollen lymph nodes. “Has anyone experienced swollen lymph nodes in their neck?” asked one member. Another shared, “The lymph nodes in my neck are swollen. Some days, more so than others. Does this have to do with MS?”

Swollen lymph nodes are not a direct symptom of MS but rather a general sign of an infection by a virus or bacteria like strep throat. Less commonly, swollen lymph nodes could be caused by rheumatoid arthritis, lupus, or some types of cancer.

Some medications used to treat MS affect the way the immune system works and make the body more likely to develop infections. People with MS may experience swollen lymph nodes if they wind up with an infection while taking MS medications that suppress (calm) their immune system.

Although swollen lymph nodes aren’t typically related to MS, it can help to understand what lymph nodes are, why they swell, and when it’s time to see a doctor.

What Are Lymph Nodes?

Lymph nodes are small, bean-shaped structures that are part of the lymphatic system — a network of vessels and tissues that helps protect the body from infections and maintain fluid balance. They play a key role in filtering out harmful substances, such as cancer cells and infectious microbes, and in moving immune cells throughout the body.

Lymph nodes are primarily located in the following areas:

• Axilla (armpit)
• Chest
• Neck
• Groin
• Abdomen (belly)

Lymph nodes contain immune cells that help the body fight off infections. They support the immune response and activate white blood cells called B lymphocytes (or B cells) to produce antibodies. Antibodies are proteins that work to fight infections.

Illnesses Associated With Swollen Lymph Nodes

Lymph nodes may become swollen when they’re working to fight off infections or due to inflammation from autoimmune disorders, injuries, or various types of cancer.

Swollen lymph nodes (also called lymphadenopathy) most commonly indicate a bacterial or viral infection. Less commonly, swollen lymph nodes develop in autoimmune diseases like rheumatoid arthritis and lupus. An autoimmune disease is a condition where the immune system mistakenly attacks the body’s own healthy cells, thinking they are harmful. Common causes of swollen lymph nodes include:

• Upper respiratory infections
• Strep throat
• Ear infections
• Mononucleosis (also called “mono”)
• Tooth infections

“I have noticed that my lymph nodes have been swollen,” wrote one MyMSTeam member. “I had a few colds, so I thought it was due to that. In addition to the two swollen ones under my jawline, I just had a sore spot appear on the side of my neck, which I think is also a lymph node.”

Does MS Affect the Lymphatic System?

Swollen lymph nodes are not a direct symptom of MS. People with MS, like the general population, may experience swollen lymph nodes. When people with MS have swollen lymph nodes, it’s likely from the usual causes — like a viral or bacterial infection — and doesn’t necessarily have anything to do with MS disease activity.

However, there are questions about how MS might affect the lymphatic system and whether it can cause swollen lymph nodes. More research needs to be done to determine whether MS causes swollen lymph nodes, but a study found that large-diameter lymph nodes were related to a shorter disease duration.

MS Medications and the Risk of Infections

Some MS medications could indirectly cause swollen lymph nodes because they can increase the risk of infections. In treating MS, neurologists often recommend disease-modifying therapy, which helps to reduce the number of MS relapses and slow disease progression.

Some disease-modifying therapy medications work by suppressing the immune system, to prevent it from causing damage to the brain and spinal cord. When the immune system is suppressed, people are at an increased risk of infections from foreign substances. Therefore, an increased risk of infection — which can cause swollen lymph nodes — is a side effect of some MS medications.

Medications used to treat relapsing-remitting MS — a type of MS where symptoms flare up (relapse) and then improve or go away (remit) — can increase the risk of infection and cause swollen lymph nodes. These treatments include:

• Alemtuzumab (sold as Campath and Lemtrada)
• Cladribine (Mavenclad)
• Fingolimod (Gilenya)
• Natalizumab (Tysabri)
• Ocrelizumab (Ocrevus)
• Siponimod (Mayzent)

Talk to Your Doctor

If an infection causes swollen lymph nodes, they usually return to normal size once the underlying infection is treated or has been successfully fought off by the immune system.

Swollen lymph nodes from a bacterial infection may be treated with antibiotics. When swollen lymph nodes are linked to autoimmune diseases or cancer, treating the underlying condition is key. Your doctor can find the cause with an exam and possibly other tests, like a blood test or biopsy.

See a doctor about swollen lymph nodes if they:

• Continue to get bigger
• Are present for two to four weeks, or longer
• Appeared for no clear reason
• Feel very hard and do not move when you push on them
• Come with other symptoms like a high fever, sore throat, unexplained weight loss, or night sweats

If you’re unsure about what might be causing your swollen lymph nodes or other symptoms, it’s always better to check with your doctor for peace of mind. If you’re having difficulty swallowing or breathing, seek medical care from a health care provider, emergency room, or urgent care immediately.

Talk With Others Who Understand

MyMSTeam is the social network for people with multiple sclerosis and their loved ones. On MyMSTeam, more than 216,000 members come together to ask questions, give advice, and share their stories with others who understand life with MS.

Do you have MS and swollen lymph nodes? Share your experience in the comments below, or start a conversation by posting on your Activities page.