The Lupus Foundation of America estimates that 1.5 million Americans and perhaps 5 million people worldwide have the autoimmune disease, in which the body’s immune system attacks and destroys healthy tissue. So how do you know if you really have the condition or if another disease is masquerading as lupus?

The autoimmune disease lupus often causes patients extreme fatigue and weakness. Pexels

Lupus is a disease of flare-ups; it comes and goes, but it affects people their entire lives. Many people think of HIV and AIDS when they hear the term “autoimmune disease,” but those conditions are marked by an underactive immune system, while lupus is overreaction. When the immune system, which is supposed to fight off viruses and other invaders, instead sends out antibodies that attack the healthy tissue, that can eventually lead to inflammation, pain or damage, the Lupus Foundation says.

Most commonly, people with lupus will experience fatigue, headaches, swollen joints or extremities, fever, chest pain, hair loss, light sensitivity, low red blood cell counts, ulcers in the nose or mouth, and a butterfly-shaped rash on the cheeks and nose. The Mayo Clinic also lists confusion, memory loss, dry eyes and a condition called Raynaud’s phenomenon in which fingers and toes turn white or blue when they are cold. Although the symptoms are numerous, they can sometimes be a bit vague: “Lupus can be difficult to diagnose because its signs and symptoms often mimic those of other ailments,” the Mayo Clinic says.

The effect on skin is usually the most visible sign of lupus, hitting about two-thirds of those with the disease. The Lupus Foundation notes those rashes or lesions described as appearing in a butterfly shape will show up on the body’s most sun-exposed areas, like the face, ears and neck. The shape of the lesions has not always been described in that way; there’s a reason the name “lupus” sounds like a condensed version of the Harry Potter character name Remus Lupin, a werewolf — a physician in the 1200s compared the facial skin lesions common with the illness to a wolf’s bite, the Lupus Foundation explains, and lupus is the Latin word for wolf.

For those wondering if they have the disease, the age of onset is usually between 15 and 44, and the Lupus Foundation says women of color are more likely to have it than whites. And while the most common form of lupus, called systemic lupus erythematosus, is believed to be caused by a combination of genetics and environment, the Centers for Disease Control and Prevention explains that there is a form of lupus stemming from a person’s overreaction to certain medications that will disappear when the meds are stopped. Those can be anti-seizure medications, blood pressure medications or even antibiotics.

Lupus can be difficult to deal with, but if you have the disease, you are not alone. Famous people with lupus include singers Selena Gomez and Seal, 3rd Rock from the Sun actress Kristen Johnston and actor Nick Cannon. Some believe composer Ludwig von Beethoven also had the chronic condition, although it has not been proven.