Chapter 2 Index

A. Evaluation by system:

1. General

2. HEENT

3. Cardiopulmonary

4. GI

5. GU

6. Orthopedics

7. Neurological

8. Skin

The Evaluation of a Rash: Is it Allergic?

How can you tell on the phone if a child has an allergic rash to antibiotics?

Answer: you can never tell if the rash is allergic, but you may be able to tell if it is not.

Characteristics of an allergic rash to antibiotics:

1. The allergic rash is generalized; this does not necessarily mean that the rash is on every part of the body, but means that it may involve face, trunk and extremities.
2. The allergic rash is urticarial, or circular in nature (as in erythema multiform). Of course the urticarial rash is itchy, and leaves blanchable purplish spots when it  fades. (This is not to be confused with true purpura, which does not blanche)
3. The allergic rash is not characterized by petechiae, is not linear, and is not localized.

Questions to ask if a possible allergic rash to an antibiotic is suspected:

1. Is the rash generalized or localized?
2. Is the rash itchy?
3. Does the rash come and go; does it leave purplish spots when it goes?
4. Are there associated symptoms of breathing difficulty, joint involvement, and swelling?

Differential diagnosis of most rashes parents think are allergic:

1. Roseola: rash starts on face and descends over the rest of the body.  This common illness often     is misdiagnosed as an antibiotic allergic rash.
2. Enteroviral infections: particularly ECHO viruses: They are generalized, involve palms and soles, are non-pruritic and often come after the fever is gone.
3. Rickettsial diseases in the summer
4. Heat rashes
5. An “Amoxicillin” rash occurs in up to 5%-8% of children taking this medication.  This rash is characterized by a generalized pinpoint non-pruritic rash that goes away if the medication is continued.

Advice to parents of child with presumed uncomplicated allergic rash that calls at night: D/C meds, and come in to the office in the morning.  If the rash were truly allergic, some remnant of it should be visible the next day.

Never tell any parent that a child is allergic to a med without seeing the child.  It is particularly important to never change antibiotics in a child because of a presumed allergic rash without seeing the rash.  The child will be stuck with the diagnosis of a penicillin allergy forever.

When does the child need to be brought in for a possible allergic rash on an emergent basis?

1. If the itching and discomfort are severe.
2. If there is associated breathing difficulty, or associated swelling of lips or tongue.
3. If the rash sounds like erythema multiform, and child’s joints are involved.

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Department of Pediatrics  |  Medical College of Georgia
Please email comments, suggestions or questions to:
John T.  Benjamin M.D.,  jbenj@mcg.edu

February 27, 2004