What is an autoimmune disease?
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.
Why does the immune system attack the 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 ().
BOTTOM LINE: Researchers don’t know exactly what causes autoimmune diseases. Diet, infections, and exposure to chemicals might be involved.
14 common autoimmune diseases
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
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.
Autoimmune disease symptoms
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.
BOTTOM LINE: Symptoms like fatigue, muscle aches, swelling, and redness could be signs of an autoimmune disease. Often symptoms come and go over time.
When to see a doctor
See a doctor if you have symptoms of an autoimmune disease. You might need to visit a specialist, depending on the type of disease you have.
- Rheumatologists treat joint diseases like rheumatoid arthritis and Sjögren’s syndrome.
- Gastroenterologists treat diseases of the GI tract, such as celiac and Crohn’s disease.
- Endocrinologists treat conditions of the glands, including Graves’ and Addison’s disease.
- Dermatologists treat skin conditions such as psoriasis.
Tests that diagnose autoimmune diseases
No single test can diagnose most autoimmune diseases. Your doctor will use a combination of tests and an assessment of your symptoms to diagnose you.
The antinuclear antibody test (ANA) is often the first test that doctors use when symptoms suggest an autoimmune disease. A positive test means you likely have one of these diseases, but it won’t confirm exactly which one you have.
Other tests look for specific autoantibodies produced in certain autoimmune diseases. Your doctor might also do tests to check for the inflammation these diseases produce in the body.
BOTTOM LINE: A positive ANA blood test can show that you have an autoimmune disease. Your doctor can use your symptoms and other tests to confirm the diagnosis.
How are autoimmune diseases treated?
Treatments can’t cure autoimmune diseases, but they can control the overactive immune response and bring down inflammation. Drugs used to treat these conditions include:
- nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Motrin, Advil) and naproxen (Naprosyn)
- immune-suppressing drugs
Treatments are also available to relieve symptoms like pain, swelling, fatigue, and skin rashes.
Eating a well-balanced diet and getting regular exercise can also help you feel better.
BOTTOM LINE: The main treatment for autoimmune diseases is with medications that bring down inflammation and calm the overactive immune response. Treatments can also help relieve symptoms.
The bottom line
More than 80 different autoimmune diseases exist. Often their symptoms overlap, making them hard to diagnose.
Autoimmune diseases are more common in women, and they often run in families.
Blood tests that look for autoantibodies can help doctors diagnose these conditions. Treatments include medicines to calm the overactive immune response and bring down inflammation in the body.