Stevens-Johnson syndrome seems to be more common in boys and has a tendency to occur in early spring and winter.

Typically, the illness begins within the first two weeks of taking the drug (if that is the cause). Most parents think that their child as the flu, since the youngster has nonspecific upper respiratory tract infection symptoms. Fever, sore throat, chills, headache, and achiness may be present. Abruptly skin lesions appear. They appear as wide spread skin eruptions consisting of large dark-red spots (caused by microscopic hemorrhage into the skin - purpura) with overlying blisters which then rupture leaving neurotic (dead tissue) centers. The typical lesion has the appearance of a target and does not usually itch the child. Infection may then set it causing skin scarring and the need for additional medication.

Lesions may continue to erupt in crops for as long as 2-3 weeks. But it is the presence of lesions on the membranes lining the eyes, mouth , and other organ systems that make Stevens-Johnson syndrome so dangerous. Involvement of the lining membranes includes redness, swelling , sloughing, blistering, ulceration, and tissue death.

Eye involvement can include ulcerations of the cornea, anterior uveitis, visual impairment and blindness . The eyes will get puffy, swollen, and gritty. There may be so many lesions inside the mouth that the child is unable to eat or drink with cracking or small blisters on the lips and mouth. Esophageal narrowing may occur when there is extensive involvement of the esophagus. If the urinary tract becomes involved, the child may complain of pain while urinating and have difficulty in voiding.