Aching joints and a rash on the face may be signs of systemic lupus erythematosus (SLE). This condition (which most doctors simply call lupus) occurs when the body's immune system mistakenly attacks healthy tissue. The most distinctive signs of lupus are a butterfly-shaped rash on the face and sore joints. Other symptoms include fatigue, weight loss, and shortness of breath. Lupus is a serious condition that may make you more likely to develop other health problems, such as heart attacks and strokes. See a doctor right away if you have signs of lupus.