Almost anyone who has lupus experiences achy joints, a low-grade fever, and extreme fatigue — all symptoms you see in fibromyalgia. But lupus is an autoimmune disorder that occurs when the body's immune system attacks its own cells and tissues. For reasons that no one knows, the body cannot tell the difference between foreign substances and its own healthy cells and tissues.

Experts estimate there are 500,000 to 1.5 million Americans who have been diagnosed with lupus. No one knows what causes the immune system to go awry. Only about 10 percent of people who have lupus have a parent or sibling with the illness, and only about 5 percent of children born to parents with lupus eventually develop it. That's why the environment is believed to play a role in the onset of lupus. Possible environmental triggers include infections, stress, antibiotics, ultraviolet light, and hormones.

Lupus can strike at any age, and occurs in both men and women, though women are ten to fifteen times more likely to get it.

Types of Lupus

Lupus is difficult to diagnose. To make matters even more complicated, there are actually three kinds of lupus:

Systemic Lupus Erythematosus (SLE)

Systemic lupus erythematosus (SLE) can affect almost any organ or system in the body. This chronic inflammatory condition alternates between flares and periods of remission. SLE is by far the most common form of lupus. It is also the most serious form, and in extreme cases it can be fatal.

Discoid Lupus

Discoid lupus is a less serious form of lupus that is limited to the skin and causes a rash on the face, neck, and scalp. About 10 percent of cases will become systemic lupus.

Drug-Induced Lupus

People who take certain medications may wind up with drug-induced lupus. Drugs that can provoke a bout of lupus include hydralazine, which is used for hypertension, and procainamide, which is used to treat irregular heart rhythms. This condition occurs only in about 4 percent of people who take these drugs and goes away when the drug is discontinued.

Symptoms and Diagnosis

More than 90 percent of people with SLE experience joint and/or muscle pain, brought on by inflammation or arthritis. Many also suffer fatigue, rashes, anemia, and sensitivity to light. Some develop a butterfly-shaped rash across the cheeks and nose. In addition, symptoms may include Raynaud's phenomenon, hair loss, and involvement of the kidneys.

Diagnosing lupus involves the presence of four of the following eleven symptoms:

• Rash over the cheeks

• Red raised patches on the skin

• Sensitivity to sunlight, resulting in rash or increase in rash

• Ulcers in the mouth or nose

• Arthritis pain in two or more joints

• Inflammation of the lining of the heart or lungs

• Excess protein or other abnormalities in the urine

• Seizures or psychosis

• Low red or white blood cell count

• Positive antinuclear antibodies (ANA) in the blood

• Positive auto-antibody tests

Many of these symptoms may not occur at the same time. Some may come and go or simply change. As a result, getting a diagnosis of lupus can sometimes take months, even years.

Treating Lupus

The goal of treatment is to prevent flares, treat them appropriately when they occur, and minimize damage to body organs. Treatment often involves a cocktail of medications that may include nonsteroidal anti-inflammatory drugs, antimalarials, corticosteroids, and immune suppressants. Just as the disease will change over time, so too will the treatments.

How Lupus Differs from FMS

Although lupus and fibromyalgia are two distinct illnesses, it's not unusual for people to have both conditions. Among people who have lupus, approximately 10 to 40 percent also eventually develop fibromyalgia.

At times, it may be difficult to distinguish lupus from fibromyalgia, especially if you have FMS and are only suffering from pain and fatigue. But while lupus and FMS have those symptoms in common, there are definite differences between the two conditions, most notably in the blood and urine.