As an autoimmune disease, multiple sclerosis (MS) commonly occurs along with other autoimmune conditions. When your immune system also attacks cells in the thyroid, a gland located at the front of your neck, you may develop thyroid disorders in addition to your MS.

Some therapies for MS are also associated with a higher risk of thyroid disease. For instance, treatment with alemtuzumab (Lemtrada) has been shown to cause thyroid disease in some people with MS.

More than 1,300 members of MyMSTeam experience hypothyroidism, which causes low thyroid hormones. “My MS led to me having a thyroid problem. My doctor is watching it,” one member shared. The relationship between thyroid disease and MS is complicated, and scientists continue to explore the connection.

What Are Autoimmune-Related Thyroid Diseases?

The thyroid is a small gland in your neck that helps control how your body uses food for energy, a process called metabolism. It does this by making hormones that regulate body functions. If the thyroid makes too much hormone, it can cause a condition called hyperthyroidism. If it makes too little, it leads to hypothyroidism.

Like MS, thyroid diseases can have an autoimmune component. Autoimmune disorders are conditions in which the immune system attacks your body’s tissues and healthy cells.

One autoimmune-related thyroid disease connected to MS is Hashimoto’s disease. This condition usually causes hypothyroidism. Graves’ disease, another autoimmune-related disease of the thyroid, causes hyperthyroidism.

Hashimoto’s Disease

Hashimoto’s disease progresses over years, sometimes co-occurring with MS. Inflammation associated with Hashimoto’s disease causes the thyroid to make fewer hormones. Hypothyroidism may cause neurological symptoms, such as memory lapses and:

• Fatigue or sluggishness
• Muscle aches, tenderness, stiffness, or weakness
• Joint pain or stiffness
• Increased sensitivity to cold
• Constipation
• Pale, dry skin
• Puffy face
• Brittle nails
• Hair loss
• Swelling of the tongue
• Weight gain
• Prolonged menstrual bleeding
• Depression
• Trouble concentrating

More than 340 MyMSTeam members have discussed having Hashimoto’s disease alongside MS. One member described joint pain: “I’ve had knee pain for about 16 years that is caused by Hashimoto's thyroiditis. Once I started having MS symptoms, it aggravated my knee pain.”

Graves’ Disease

Graves’ disease is also associated with MS. Signs and symptoms of an overactive thyroid include:

• Anxiety or irritability
• Tremor of the hands or fingers
• Fatigue
• Heat sensitivity
• Heart palpitations
• Warm, moist skin and increased sweating
• Weight loss
• Bulging eyes
• Irregular menstrual cycles
• Reduced libido (desire to have sex) and erectile dysfunction
• Frequent bowel movements
• Thick, darkened skin on the tops of the feet or shins
• Sleep problems

More than 100 MyMSTeam members have reported experiencing Graves’ disease alongside their MS.

One member shared their frustrations with fluctuating thyroid hormones. “My thyroid hormone levels go crazy at times,” they said. “One day they can be normal, the next not. I also can tell when they are off. My husband can too. I become very irritable — basically, just pure mean!”

Why Does Thyroid Disease Occur in People With MS?

Although MS may not directly cause thyroid disease, people with MS have a significantly higher risk of thyroid disease.

A 2024 study in Health Science Reports found that thyroid-stimulating hormone (TSH) levels were more likely to be abnormal (either high or low) among people with MS. The researchers also noted that females with MS were more likely than males to experience thyroid dysfunction.

Researchers believe that thyroid disease and MS may be associated in two ways — shared risk factors and certain medications.

Shared Risk Factors

Research suggests that MS has many risk factors. Some of these are tied to the environment, and others are genetic. For example, habits and conditions that cause inflammation, such as smoking and obesity (a body mass index above 30), are thought to activate genetic processes that may lead to MS.

Thyroid diseases such as hypothyroidism and Graves’ disease also have a range of risk factors. These include links to other autoimmune conditions like rheumatoid arthritis (an inflammatory disease) and type 1 diabetes, as well as family history. This suggests that genetics play an important role in thyroid disorders too.

MS and autoimmune-related thyroid diseases share some common risk factors. For instance, research shows that certain genetic pathways and imbalances in regulatory T cells (a type of white blood cell) are involved in both MS and Hashimoto’s disease.

Overall, shared genetic factors may affect how the endocrine system (which includes the thyroid) and the central nervous system work. These changes may affect thyroid function — and possibly the development of MS. More research is needed to understand how MS and thyroid disorders are connected.

Thyroid Disease and Treatments for MS

Some treatments for MS may help explain why thyroid problems often occur alongside MS.

Treatment with alemtuzumab in people with MS has been shown to raise the risk of thyroid disease. In fact, thyroid autoimmune dysfunction — especially Graves’ disease — can develop in up to 40 percent of people who take alemtuzumab for MS. One study found that people with MS who developed autoimmune thyroid disease after being treated with alemtuzumab responded better to the drug than people who didn’t develop autoimmune thyroid disease.

Another study found that treatment with interferon-beta therapy, another common MS treatment, may increase the risk of thyroid disorders. Interferon-beta therapy, alemtuzumab, and other disease-modifying therapies (DMTs) improve symptoms of MS by changing the way the immune system behaves. However, they may cause thyroid problems as a side effect.

If you’re concerned about thyroid problems as a side effect of MS treatment, talk with your health care provider. Thyroid problems can often be managed with medication while you continue your DMT.

Find Your Team

MyMSTeam is the social network for people with multiple sclerosis and their loved ones. More than 217,000 members come together to ask questions, give advice, and share their stories with others who understand life with multiple sclerosis.

Are you living with multiple sclerosis and thyroid disease? Share your experience in the comments below, start a conversation by posting on your Activities page, or connect with like-minded members in Groups.