Discerning Between Rash from Strep Throat and Antibiotic Allergy

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Discerning Between Rash from Strep Throat and Antibiotic Allergy

Question:

My five-month-old child was diagnosed with strep and was put on antibiotics, but now has a rash all over. How can I tell if this is scarlet fever or an allergic reaction to the antibiotic?

Answer:

The rash of scarlet fever looks very different than an allergic rash due to an antibiotic.

The rash of scarlet fever is found in the body's creases, such as around the neck, under the arms, or in the groin area. The rash can have small bumps and can feel rough like sandpaper. After about a week, the rash may begin to fade and the skin may begin to peel.

Hives are a common sign of an allergic reaction. Hives appear as pale bumps surrounded by reddened areas of skin that are itchy. They can vary in size and appear in different shapes anywhere on the body. Hives can be a bother because of the blotchy rash all over the skin that is itchy. It is often hard to figure out exactly what caused the hives. Most cases of hives clear up on their own.

Other symptoms that may appear with scarlet fever are a fever and sore throat. Strep throat can occur in any age child, and at any time of the year. Most often, it is seen in school-aged children and adolescents during the winter and early spring.

It is less common for an infant to be diagnosed with scarlet fever. However, if your doctor feels this rash looks like it, an antibiotic is the right treatment. Strep throat must be treated to prevent rheumatic fever, a serious condition that affects the joints and the heart.

Henry (Hank) Bernstein, D.O. is a Senior Lecturer in Pediatrics at Harvard Medical School and Professor of Pediatrics at Dartmouth Medical School. Formerly the Associate Chief of General Pediatrics and Director of Primary Care at Children's Hospital Boston, he currently is the Chief of General Academic Pediatrics at Children's Hospital at Dartmouth. He has extensive and varied experience as a primary care pediatrician, and is a spokesperson for the news media on a variety of pediatric health care topics, including vaccination, common childhood illnesses, and practical information for caregivers.

Last updated:	July 20, 2009