November 2026
Your immune system is designed to protect your body by fighting off bacteria, viruses, and other harmful invaders. But in people with an autoimmune disease, the immune syst em mistakenly attacks healthy cells, tissues, or organs instead.
Scientists have identified more than 80 autoimmune diseases. A nationwide study published in 2025 found that about 15 million people (4.6%) in the U.S. have been diagnosed with at least one autoimmune disease.
Learn about common autoimmune diseases, symptoms, risk factors, and trends.
Common autoimmune diseases
According to that same 2025 study in the Journal of Clinical Investigation, the five most commonly diagnosed autoimmune diseases in the U.S. are:
- Rheumatoid arthritis (RA), which attacks the joint linings, causing pain and swelling.
- Psoriasis, which speeds up the growth of skin cells and leads to raised, scaly patches of skin.
- Type 1 diabetes, which destroys the cells in the pancreas that produce insulin.
- Graves’ disease, which makes the thyroid overactive.
- Autoimmune thyroiditis (primarily Hashimoto’s thyroiditis), which is the top cause of hypothyroidism (underactive thyroid).
Autoimmune disease symptoms
Autoimmune disease symptoms tend to be vague and there’s a lot of overlap between diseases.
Common symptoms of autoimmune diseases include:
- Fatigue
- Joint pain and swelling
- Muscle aches
- Low-grade fever
- Weight loss or gain
- Dizziness
- Trouble thinking clearly or concentrating
- Rashes
- Digestive problems
A hallmark of an autoimmune disease is that symptoms flare up and then quiet down rather than staying constant.
Who is most at risk for autoimmune disease?
Several factors may increase risk:
- Being female. Women are almost twice as likely as men to be diagnosed with an autoimmune disease, likely due to a combination of genetic and hormonal factors.
- Family history. Certain genes raise your chances of developing an autoimmune disease.
- Already having one autoimmune disease. Among people with at least one autoimmune disease, 34% have more than one.
- Certain infections. Some infections appear to increase the risk of certain autoimmune conditions.
- Smoking. Smoking is a well-known risk factor for rheumatoid arthritis and may contribute to other autoimmune conditions as well.
Are autoimmune diseases increasing?
The evidence increasingly points to yes.
In the U.S., the share of people testing positive for antinuclear antibodies, a marker of autoimmunity, rose from about 11% to nearly 16% over two decades.
Why? Better diagnosis explains part of it, but researchers point to environmental and lifestyle changes, including:
- Ultra-processed diets
- Obesity
- Reduced early-life exposure to microbes
- Environmental chemicals
If autoimmune disease runs in your family, or you have persistent, unexplained symptoms, talk to your healthcare provider. Getting the right diagnosis can take time, but early evaluation may help you get answers and start treatment sooner.
