An autoimmune disease is a condition in which your immune system mistakenly attacks your body.
The immune system normally guards against germs like bacteria and viruses. When it senses these foreign invaders, it sends out an army of fighter cells to attack them.
Normally, the immune system can tell the difference between foreign cells and your own cells.
In an autoimmune disease, the immune system mistakes part of your body — like your joints or skin — as foreign. It releases proteins called autoantibodies that attack healthy cells.
Some autoimmune diseases target only one organ. Type 1 diabetes damages the pancreas. Other diseases, like lupus, affect the whole body.
Doctors don’t know what causes the immune system misfire. Yet some people are more likely to get an autoimmune disease than others.
Women get autoimmune diseases at a rate of about 2 to 1 compared to men — 6.4 percent of women vs. 2.7 percent of men. Often the disease starts during a woman’s childbearing years (ages 14 to 44).
Some autoimmune diseases are more common in certain ethnic groups. For example, lupus affects more African-American and Hispanic people than Caucasians.
Certain autoimmune diseases, like multiple sclerosis and lupus, run in families. Not every family member will necessarily have the same disease, but they inherit a susceptibility to an autoimmune condition.
Because the incidence of autoimmune diseases is rising, researchers suspect environmental factors like infections and exposures to chemicals or solvents might also be involved.
A “Western” diet is another suspected trigger. Eating high-fat, high-sugar, and highly processed foods is linked to inflammation, which might set off an immune response. However, this hasn’t been proven.
Another theory is called the hygiene hypothesis. Because of vaccines and antiseptics, children today aren’t exposed to as many germs as they were in the past. The lack of exposure could make their immune system overreact to harmless substances.
There are more than 80 different autoimmune diseases. Here are 14 of the most common ones.
1. Type 1 diabetes
The pancreas produces the hormone insulin, which helps regulate blood sugar levels. In type 1 diabetes, the immune system attacks and destroys insulin-producing cells in the pancreas.
High blood sugar can damage blood vessels, as well as organs like the heart, kidneys, eyes, and nerves.
2. Rheumatoid arthritis (RA)
In Rheumatoid arthritis (RA), the immune system attacks the joints. This attack causes redness, warmth, soreness, and stiffness in the joints.
Unlike Osteoarthritis, which affects people as they get older, RA can start as early as your 30s .
3. Psoriasis/psoriatic arthritis
Skin cells normally grow and then shed when they’re no longer needed. Psoriasis causes skin cells to multiply too quickly. The extra cells build up and form red, scaly patches called scales or plaques on the skin.
About 30 percent of people with psoriasis also develop swelling, stiffness, and pain in their joints. This form of the disease is called psoriatic arthritis.
4. Multiple sclerosis
Multiple sclerosis (MS) damages the myelin sheath — the protective coating that surrounds nerve cells. Damage to the myelin sheath affects the transmission of messages between your brain and body.
This damage can lead to symptoms like numbness, weakness, balance issues, and trouble walking. The disease comes in several forms, which progress at different rates. About 50 percent of people with MS need help walking within 15 years after getting the disease .
5. Systemic lupus erythematosus (lupus)
Although doctors in the 1800s first described lupus as a skin disease because of the rash it produces, it actually affects many organs, including the joints, kidneys, brain, and heart.
Joint pain, fatigue, and rashes are among the most common symptoms.
6. Inflammatory bowel disease
Inflammatory bowel disease (IBD) is a term used to describe conditions that cause inflammation in the lining of the intestines. Each type of IBD affects a different part of the GI tract.
- Crohn’s disease can inflame any part of the GI tract, from the mouth to the anus.
- Ulcerative colitis affects only the lining of the large intestine (colon) and rectum.
7. Addison’s disease
Addison’s disease affects the adrenal glands, which produce the hormones cortisol and aldosterone. Having too little of these hormones can affect the way the body uses and stores carbohydrates and sugar.
Symptoms include weakness, fatigue, weight loss, and low blood sugar.
8. Graves’ disease
Graves’ disease attacks the thyroid gland in the neck, causing it to produce too much of its hormones. Thyroid hormones control the body’s energy usage, or metabolism.
Having too much of these hormones revs up your body’s activities, causing symptoms like nervousness, a fast heartbeat, heat intolerance, and weight loss.
One common symptom of this disease is bulging eyes, called exophthalmos. It affects up to 50 percent of people with Graves’ disease.
9. Sjögren’s syndrome
This condition attacks the joints, as well as glands that provide lubrication to the eyes and mouth. The hallmark symptoms of Sjögren’s syndrome are joint pain, dry eyes, and dry mouth.
10. Hashimoto’s thyroiditis
In Hashimoto’s thyroiditis, thyroid hormone production slows. Symptoms include weight gain, sensitivity to cold, fatigue, hair loss, and swelling of the thyroid (goiter).
11. Myasthenia gravis
Myasthenia gravis affects nerves that help the brain control the muscles. When these nerves are impaired, signals can’t direct the muscles to move.
The most common symptom is muscle weakness that gets worse with activity and improves with rest. Often muscles that control swallowing and facial movements are involved.
Vasculitis happens when the immune system attacks blood vessels. The inflammation that results narrows the arteries and veins, allowing less blood to flow through them.
13. Pernicious anemia
This condition affects a protein called intrinsic factor that helps the intestines absorb vitamin B-12 from food. Without this vitamin, the body can’t make enough red blood cells.
Pernicious anemia is more common in older adults. It affects 0.1 percent of people in general, but nearly 2 percent of people over age 60.
14. Celiac disease
People with celiac disease can’t eat foods containing gluten — a protein found in wheat, rye, and other grain products. When gluten is in the intestine, the immune system attacks it and causes inflammation.
Celiac disease affects about 1 percent of people in the United States. A larger number of people have gluten sensitivity, which isn’t an autoimmune disease, but can have similar symptoms like diarrhea and abdominal pain.
The early symptoms of many autoimmune diseases are very similar, such as:
- achy muscles
- swelling and redness
- low-grade fever
- trouble concentrating
- numbness and tingling in the hands and feet
- hair loss
- skin rashes
Individual diseases can also have their own unique symptoms. For example, type 1 diabetes causes extreme thirst, weight loss, and fatigue. IBD causes belly pain, bloating, and diarrhea.
With autoimmune diseases like psoriasis or RA, symptoms come and go. Periods of symptoms are called flare-ups. Periods when the symptoms go away are called remissions.