Symptoms and Diagnosis of Chickenpox - Varicella

About 24 to 36 hours after the first symptoms begin, a rash of small, flat, red spots appears. The spots usually begin on the trunk and face, later appearing on the arms and legs. Some children have only a few spots; others have them almost everywhere, including on the scalp and inside the mouth. Over 6 to 8 hours, each spot becomes raised; forms an itchy, round, fluid-filled blister against a red background; and finally crusts. Spots continue to develop and crust for several days. The spots may become infected by bacteria (see Bacterial Skin Infections: Introduction), causing erysipelas, pyoderma, cellulitis, or bullous impetigo.

New spots usually stop appearing by the fifth day, the majority are crusted by the sixth day, and most disappear in fewer than 20 days. Spots in the mouth quickly rupture and form raw sores (ulcers), which often make swallowing painful. Raw sores may also occur on the eyelids and in the upper airways, rectum, and vagina. Spots in the voice box (larynx) and upper airways may occasionally cause severe difficulty in breathing. Lymph nodes at the side of the neck may become enlarged and tender. The worst part of the illness usually lasts 4 to 7 days.

Lung infection occurs in about 1 out of 400 people, especially adolescents and adults, resulting in cough and difficulty breathing. Brain infection (encephalitis) is less common and produces unsteadiness in walking, headache, dizziness, confusion, and seizures. Heart infection sometimes causes a heart murmur. Joint inflammation produces joint pain.

Reye's syndrome, a rare but very severe complication that occurs almost only in those younger than 18, may begin 3 to 8 days after the rash begins. A doctor is usually certain of the diagnosis of chickenpox because the rash and the other symptoms are so typical. Measurement of the levels of antibodies in the blood and laboratory identification of the virus are rarely needed.