Lupus, also called systemic lupus erythematosus or SLE, is a disease that affects your immune system. Normally, your immune system fights infections caused by germs. Instead of protecting your body, your immune system makes the mistake of attacking your body's healthy cells.

Diagnosis - Lupus Image Credit. Tashatuvango / Shutterstock

Lupus can affect almost any part of your body, including your joints, skin, kidneys, heart, lungs, blood vessels, and brain. There is no way to know what part of your body will be affected.

For most people though, lupus is a mild disease affecting only a few parts of your body, and some patients don't get inner organ problems (like in the heart and lungs), but do have skin and joint problems.

Normally, lupus develops slowly, with symptoms that come and go. For some, it can cause serious and even life-threatening problems.

Even for patients with diseases that hurt their organs, with good care and management and a strong partnership between a patient and her health care provider, the prognosis is good.

Lupus affects up to 1.4 million people in the United States. About 9 out of 10 people who have lupus are women.

Lupus is 3 times more common in black women than in white women. It is also more common in women of Hispanic/Latina, Asian, and American Indian descent.

Black and Hispanic/Latina women tend to develop symptoms at an earlier age than other women. African Americans have more severe organ problems, especially with their kidneys.

Each person with lupus has slightly different symptoms that can range from mild to severe and may come and go over time.

Because many people with lupus are sensitive to sunlight (called photosensitivity), skin rashes often first develop or worsen after sun exposure.

In an autoimmune disorder like lupus, the immune system cannot tell the difference between foreign substances and its own cells and tissues.

The immune system then makes antibodies that, simply put, attack the body itself. This causes inflammation, pain and damage to various organs.

Sometimes people with lupus experience a "flare." This occurs when some symptoms appear for short periods then disappear.

Even if you take medicine for lupus, you may find that there are times when the symptoms become worse.

Learning to recognize that a flare is coming can help you take steps to cope with it. Many people feel very tired or have pain, a rash, a fever, stomach discomfort, headache, or dizziness just before a flare.

There is no one test to diagnose lupus, and it may take months or years to make the diagnosis. There is no cure for lupus, but medicines and lifestyle changes can help control it.

Also called: Discoid lupus, SLE, Subacute cutaneous lupus, Systemic lupus erythematosus.

What Causes Lupus?

The cause of lupus is not known. It is likely that there is no single cause but a combination of genetic, environmental, and possibly hormonal factors that work together to cause the disease.

Lupus is not contagious-you can't catch it from someone. No specific "lupus gene" has been found, but it does run in families.