Why (and Which) Autoimmune Diseases Are More Common in Women

Autoimmune diseases are four times more common in women than men. In fact, women make up 80% of people diagnosed with an autoimmune disease. Although experts don't know the exact reason for this gender gap, they have a few ideas. Autoimmune diseases are triggered by a mix of genes and environment, such as your diet and exposure to chemicals or other toxins. Women's hormones, DNA, and immune systems have key differences that make them more likely to have an autoimmune disease.

Women have a stronger immune response. This helps them fight off infections better and recover faster than men. But there's a catch for people with a family history of autoimmune diseases. Although both men and women can have genes that put them at risk, women have a greater chance of developing an autoimmune disease. They're more likely to have an overactive immune response that triggers those genes. This causes the immune system to turn on itself and attack healthy parts of the body.

Many autoimmune diseases in women happen after pregnancy, puberty, or menopause. That's because these events cause a major shift in hormones, which impacts the immune system. The female sex hormone estrogen boosts immune cell function, while the male sex hormone dampens it. These changes can throw off the immune system, trigger inflammation, and set off reactions that lead to an autoimmune disease.

Your DNA is housed in structures called chromosomes. Women have two X chromosomes, while men have an X and Y chromosome. Usually, females shut down the activity of one of the X chromosomes. Issues with X-chromosome inactivation (XCI), which involves proteins that the body can mistake as foreign invaders and attack, are linked to higher rates of autoimmune diseases in women. What's more, certain genes act differently in women than in men. They're more likely to trigger inflammatory pathways linked with autoimmune diseases.

Along with genetics, your environment plays a role in developing an autoimmune disease. Smoking, toxins, UV light exposure, medications, and infections can trigger autoimmune diseases. Women are more likely to encounter some of these risk factors, such as the toxins in some cosmetics, nail polish, and hair dye. Birth control and hormone replacement therapy can also raise the odds of some autoimmune diseases, such as lupus and rheumatoid arthritis. They increase estrogen levels, which may rev up the immune system.

These autoimmune diseases overwhelmingly strike women. With Sjogren's disease and Hashimoto's disease, diagnoses in women outnumber those in men by as much as 19 times. 

• Lupus. Also called systemic lupus erythematosus (SLE), this disease damages the joints, heart, lungs, skin, kidneys, and more. Symptoms include a fever, painful joints, and a butterfly-like rash over the nose and cheeks.
• Sjogren's disease. The immune system attacks glands that make moisture, such as tears and saliva. This can make your eyes and mouth dry.
• Hashimoto's disease. With this disease, the thyroid doesn't make enough thyroid hormone. Low levels of thyroid hormones can trigger fatigue, shortness of breath, and cold hands and feet.

These conditions also strike at least three times more women than men. 

• Scleroderma. The body makes too much collagen, a protein in skin, tendons, and blood vessels. Symptoms include thick, waxy skin and painful joints.
• Graves' disease. This causes the thyroid to make too much thyroid hormone, which can lead to insomnia, weight loss, and bulging eyes.
• Rheumatoid arthritis. The immune system attacks the lining of the joints. The main symptom is painful, stiff, and swollen joints.
• Multiple sclerosis. This disease strikes the protective nerve coating in the brain and spinal cord. This causes issues with balance, coordination, speaking, and walking.

These autoimmune diseases are more common in women, though psoriasis and type 1 diabetes may be slightly more common in men, according to some studies. 

• Psoriasis causes thick, red skin patches, usually covered in scales.
• Celiac disease is when people can't have gluten, a protein found in wheat, rye, and barley. Symptoms include stomach pain and bloating.
• Alopecia areata strikes hair follicles and causes hair loss.
• Vitiligo results in white patches on the skin. 
• Inflammatory bowel disease causes chronic inflammation in the digestive system, resulting in weight loss, rectal bleeding, and more.
• Type 1 diabetes attacks the cells that make insulin and leads to high blood sugar. Signs of the disease include increased thirst, frequent urination, and weight loss.

These rare autoimmune diseases strike more women than men.

• Hemolytic anemia attacks red blood cells. Symptoms may include dizziness and cold hands and feet.
• Primary biliary cholangitis destroys the liver's bile duct. Signs include itchy skin and a yellowing of the eyes and skin.
• Autoimmune hepatitis strikes the liver and can result in joint pain, itchy skin, and exhaustion.
• Guillain-Barre syndrome affects brain and spinal cord nerves. You'll feel tingling or weakness in your legs that can spread to your upper body.
• Antiphospholipid antibody syndrome strikes blood vessels and causes blood clots.
• Myasthenia gravis damages nerves and muscles, which can lead to weakness, double vision, and trouble swallowing and talking.

About 80% of people diagnosed with fibromyalgia and chronic fatigue syndrome are women. Both conditions are sometimes mistaken for autoimmune diseases, because they cause similar symptoms. Chronic fatigue syndrome can cause you to feel very tired, have muscle pain, feel weak, and have brain fog. People with fibromyalgia have painful or tender spots all over their body. They may also have morning stiffness, sleep issues, and exhaustion. Experts aren't sure what causes these conditions, but they're not autoimmune diseases.

Women can develop an autoimmune disease at any age, but certain diseases tend to be more likely to happen in certain phases of life. 

• Teens and 20s: Changing hormones in puberty can trigger an autoimmune disease. Multiple sclerosis, type 1 diabetes, and lupus are often diagnosed during women's teens and early 20s.
• Ages 30 to 50: The immune system is active during this time, thanks in part to the hormones of pregnancy and perimenopause. Rheumatoid arthritis and Hashimoto's disease are commonly detected during this age.
• Age 50 and beyond: Women still have hormonal shifts because of perimenopause and menopause. Lupus, rheumatoid arthritis, and Sjogren's disease are common after age 50.