A 34-year-old woman comes to the emergency department with a rash and pruritus. She had a sore throat for several days and took some prescription medication (amoxicillin) left over from 1 year ago. The itchy rash developed about 20-30 minutes after she took the first pill 4 hours ago. She has no dyspnea, dizziness, nausea, diarrhea, or abdominal cramps. She has no prior history of skin rash or allergies. Her temperature is 36.7° C (98° F), blood pressure is 124/82 mm Hg, and pulse is 80/min. Oxygen saturation is 98% on room air. Physical examination shows multiple urticaria and mild excoriations over the upper and lower extremities and upper body. The tonsils are mildly erythematous but without exudates or swelling. There is no lymph node enlargement. Lungs are clear on auscultation without wheezes. There is no stridor. Abdominal examination is unremarkable. Which of the following is the best next step in management of this patient?

Question

A 34-year-old woman comes to the emergency department with a rash and pruritus.  She had a sore throat for several days and took some prescription medication (amoxicillin) left over from 1 year ago.  The itchy rash developed about 20-30 minutes after she took the first pill 4 hours ago.  She has no dyspnea, dizziness, nausea, diarrhea, or abdominal cramps.  She has no prior history of skin rash or allergies.  Her temperature is 36.7° C (98° F), blood pressure is 124/82 mm Hg, and pulse is 80/min.  Oxygen saturation is 98% on room air.  Physical examination shows multiple urticaria and mild excoriations over the upper and lower extremities and upper body.  The tonsils are mildly erythematous but without exudates or swelling.  There is no lymph node enlargement.  Lungs are clear on auscultation without wheezes.  There is no stridor.  Abdominal examination is unremarkable.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This patient's symptoms are typical of mild drug-induced hypersensitivity reaction, type 1. Some patients can form drug-specific immunoglobulin E (IgE) on exposure to a medication, although most do not. Once formed, the drug-specific IgE occupies receptors on mast cells and basophils. If the drug is encountered again, these cells may activate, resulting in symptoms. Onset is rapid (seconds to minutes) and symptoms can range from mild (eg, urticaria, pruritus, flushing) to more severe (eg, angioedema of the larynx, anaphylaxis). Most commonly implicated in type 1 reactions are beta lactam drugs, neuromuscular blocking agents, quinolones, platinum-containing chemotherapeutic agents, and foreign proteins (eg, chimeric antibodies). urticaria Urticaria and pruritus without systemic symptoms are usually treated with antihistamines, and treatment with the offending drug is discontinued (Choice C). (Choices A and B) Treatment with epinephrine and corticosteroids is reserved for more severe reactions accompanied by systemic symptoms (eg, anaphylaxis). This patient has no respiratory symptoms (dyspnea, wheezes, stridor) or abdominal symptoms (diarrhea, cramps) and her vital signs are stable without hypotension or hypoxia. Epinephrine and corticosteroids therefore are not required. (Choice D) In patients with infectious mononucleosis secondary to Epstein-Barr virus, a polymorphous, maculopapular rash may develop after administration of amoxicillin and other antibiotics. Unlike drug-induced type 1 reactions, which occur immediately, this rash typically develops after 24 hours. In addition, patients with infectious mononucleosis typically present with fever, fatigue, exudative pharyngitis, and posterior cervical lymphadenopathy. Educational objective: Drug-induced type 1 hypersensitivity reactions are immediate in onset and mediated by IgE and mast cells/basophils. Mild manifestations of a drug allergy (eg, urticaria and pruritus without systemic symptoms) are usually treated with antihistamines and discontinuation of the offending drug.

A 34-Year-Old Woman Comes to the Emergency Department with a Rash