Symptoms of measles usually develop 8 to 12 days after a person has been exposed to the virus. But the incubation period-the time between when you are first exposed to the measles virus and when you develop symptoms-can range from 7 to 18 days. Early symptoms of measles include fever [101F and higher], runny nose, sneezing, sore throat, hacking cough, swollen glands, fatigue, diarrhea, and loss of appetite. Many times, the eyes become red, irritated, swollen, and sensitive to light. There may be a discharge from the eyes.

These symptoms usually last 3 to 5 days. Toward the end of this phase, red spots with tiny grayish white heads, called Koplik spots, appear on the inside of the cheeks at the back of the mouth. These spots disappear within 18 hours, and a blotchy rash follows. It first develops on the face and behind the ears and spreads downward over the entire body. A fever of 104F or higher often develops with the rash but drops in about 2 days.

The rash lasts about 5 days and usually causes only slight itching, if any. The rash fades in the same order it appeared. After the rash disappears, the skin may have a brownish discoloration, which gradually fades away.

A person who has measles can spread the disease to others from 4 days before the rash breaks out to 4 days after the rash appeared.