What Is an Autoimmune Disease?

Medically Reviewed by Zilpah Sheikh, MD on October 04, 2023
9 min read

Autoimmune diseases result when your immune system is overactive, causing it to attack and damage your body's own tissues.

Normally, your immune system creates proteins called antibodies that work to protect you against harmful substances such as viruses, cancer cells, and toxins. But with autoimmune disorders, your immune system can't tell the difference between invaders and healthy cells.

Doctors have identified more than 100 different autoimmune diseases, which together affect over 24 million people in the U.S. It's not clear exactly what causes or triggers them. Treatment usually focuses on reducing immune system activity.

Some examples of autoimmune diseases are:

What's the most common autoimmune disease?

Doctors don't agree on which autoimmune disorder is most common. Because there are so many different types, there's no one way that they're reported. Many of them are also hard to diagnose, so people may have them without knowing it. But some of the most common types are type 1 diabetes, MS, RA, lupus, Crohn's disease, and psoriasis.

The exact causes of autoimmune diseases are unknown, but scientists have some theories on what triggers them:

  • Certain medications. Some drugs may cause changes in your body that confuse your immune system. Talk to your doctor about the side effects of statins, antibiotics, and blood pressure medications in particular.

  • Genetics. Some autoimmune diseases run in families, so you're at higher risk if your family has a history of them. People who have certain genes may also be more likely to have autoimmune disorders. While genes do play a role, they aren't enough to cause an autoimmune disease on their own.

  • Infections. Microorganisms like viruses and bacteria could set off changes that make your immune system attack itself. This may be more likely if you're genetically prone to immune system disease.

Certain risk factors raise your chances of getting an autoimmune disorder. Some common ones include:

  • Smoking
  • Exposure to toxins, such as air pollution or hazardous chemicals
  • Female gender, or having been assigned female at birth (78% of people with an autoimmune disease are women)
  • Obesity

While signs of autoimmune diseases differ depending on the type and location of the condition you have, some symptoms that are common to many include:

  • Fatigue
  • Frequent fevers
  • A general sick feeling
  • Joint pain and swelling
  • Skin problems, such as redness or rashes
  • Stomach pain or digestion issues
  • Swollen glands

A diagnosis may take time and several different kinds of tests to confirm. The symptoms of many autoimmune diseases look like those of other conditions, so it can take months or even years to get the right diagnosis.

Your doctor may start by interviewing you about your symptoms and health history. Then, they may run some tests commonly used to help diagnose autoimmune disorders.

Blood tests

Your doctor can use different blood tests to cross-check any symptoms you've described. One common test, known as an autoantibody screen, looks for antibodies that are attacking your own tissues (autoantibodies). While the presence of autoantibodies in your blood isn’t enough to confirm an autoimmune disease diagnosis, it's a start.

Other blood tests your doctor may use include:

  • Antinuclear antibody test (ANA)
  • Complete blood count (CBC)
  • Erythrocyte sedimentation rate (ESR)
  • Comprehensive metabolic panel
  • C-reactive protein (CRP)
  • Urinalysis


Your doctor can use these tests to look for visible signs of an autoimmune disease. For instance, ultrasounds and x-rays can reveal joint issues, and MRIs can show damage deep in your body.

While there aren't any cures for autoimmune diseases yet, there are many kinds of treatment that help control your immune system response and manage your symptoms.


Your doctor can prescribe different medications depending on the type of autoimmune disorder you have, how serious it is, and what your symptoms are. Some drugs they may use to tamp down an overactive immune reaction include:

Steroids. A group of drugs called corticosteroids are often the first treatment because they work quickly and effectively to lessen your immune system's overactive response. But these slow down your entire immune system, which can come with serious side effects.

Some other drugs focus only on slowing down part of your immune system and come with fewer side effects. These can target cells that make certain antibodies or get rid of specific proteins in your immune system.

Anti-inflammatory drugs. These medications help control your immune system while still supporting organ function. For instance, anti-TNF medications fight tumor necrosis factor (TNF), a protein that spurs inflammation. These are used to treat some forms of autoimmune arthritis and psoriasis. And nonsteroidal anti-inflammatory drugs (NSAIDs) help ease pain, swelling, and stiffness.

Then there are drugs and treatments to help manage symptoms, including:

  • Painkillers
  • Medications for depression and anxiety
  • Insulin shots
  • Sleep medications
  • Plasma exchanges, in which a machine draws some of your blood, removes troublesome antibodies, and returns it to your body
  • Creams and pills for rashes
  • Intravenous immune globulin (IVIg), a blood product made up of antibodies that can help correct your immune system without stopping its normal function

Your doctor may prescribe medications to supplement substances your body is low on due to your autoimmune disease, such as insulin, thyroid hormone, or vitamin B12.

If the disorder affects your blood, they may also do blood transfusions.

Lifestyle changes

Aside from medications, doctors often suggest shifts in personal habits as part of treatment. Exercise or physical therapy are common for autoimmune diseases that affect your muscles, such as myositis and multiple sclerosis. For those with autoimmune diseases that affect blood vessels, quitting smoking can help.


There are many types of autoimmune diseases, which result when your immune system mistakenly attacks healthy body tissues. Scientists aren't sure why this happens. Most treatments aim to calm your overactive immune system.


What are the 10 most common autoimmune diseases?

While there are more than 100 different kinds of autoimmune disorders, the most common ones include:

  1. Inflammatory bowel disease (Crohn's disease, ulcerative colitis)
  2. Rheumatoid arthritis (RA)
  3. Lupus
  4. Type 1 diabetes
  5. Multiple sclerosis (MS)
  6. Scleroderma
  7. Psoriasis
  8. Psoriatic arthritis 
  9. Thyroid diseases
  10. Sjögren’s syndrome

What are the most serious autoimmune diseases?

While any autoimmune disease can be hard to manage day to day, there are a few that can be fatal:

  • Giant cell myocarditis. Though rare, giant cell myocarditis is a life-threatening autoimmune condition that attacks your heart muscle. It has a one-year death rate of 70%.

  • Mixed connective tissue disease (MCTD). Also rare, this disease has the symptoms of a range of autoimmune diseases such as lupus, scleroderma, and polymyositis. Many people with MCTD also have Sjögren’s syndrome, and the disease can lead to serious problems, some of which can be fatal.

  • Anti-NMDA receptor encephalitis. Often misdiagnosed as other psychotic conditions, this autoimmune disease causes the body to disrupt normal brain signals and makes the brain swell. While people tend to have less serious symptoms at first, their condition often worsens quickly, requiring hospitalization. 

What can trigger autoimmune disease?

Typically, one or more triggers in your everyday environment can make your immune system start to attack itself. Some things that can cause an autoimmune disease include:

  • Too much sun exposure
  • Certain viruses
  • Specific kinds of chemicals
  • Genetics
  • Injury or tissue damage
  • A preexisting autoimmune disease
  • Exposure to toxins
  • Certain medications
  • Obesity
  • Smoking

Is eczema an autoimmune disease?

While your immune system plays a role in eczema, and drugs that suppress your immune system can treat it, it's not technically considered an autoimmune disorder. That's because it doesn't result from an immune system attack on a specific target in your body.