Treating A Non-Pruritic Rash That Occurred After Antibiotic Use

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William Fishco, DPM, FACFAS

   Urticaria is a vascular reaction of the skin that leads to erythematous plaques, which typically have moderate to severe pruritus. An important clinical feature of the urticarial wheal is the ability of complete blanching with pressure. Urticaria may be the result of food and drug allergies, insect bites and contact hypersensitivities such as latex. Urticaria may also result from medical conditions such as infections, autoimmune disorders, pregnancy, thyroid dysfunction and serum sickness.

What You Should Know About Erythema Nodosum

The correct diagnosis for the patient is erythema nodosum. The etiology was most likely his recent infection or a drug-induced reaction to the antibiotics that he completed. When reviewing the conditions associated with similar rashes, you will note the commonality with etiology. Many of the associated conditions involve drug eruptions (with similar classes of drugs), infections and autoimmune disorders.

   Keys to making the correct diagnosis involved the lack of the following: high fever, leukocytosis, blistering or central clearing of the lesions, and pruritus. Other key factors were his history as a healthy young man with recent infection and the fact that he had completed a course of a penicillin-based antibiotic.

   Erythema nodosum has its peak incidence in 20- to 40-year-olds with a predilection for women. Streptococcal infections are the most common cause of erythema nodosum in children. Drugs, autoimmune diseases and inflammatory bowel diseases (i.e. ulcerative colitis) are typically the causes in adults.

   If there is uncertainty with making the diagnosis based on history and physical exam, standard further testing may include: punch biopsy of the lesion, complete blood count, antistreptolysin-O titer, throat culture, tuberculin test and a chest X-ray to rule out pulmonary diseases such as tuberculosis, sarcoidosis or coccidioidomycosis.

Pertinent Insights On Effective Treatment

Erythema nodosum is a self-limiting condition. Typically, it takes four to eight weeks for the lesions to resolve. Certainly treating the underlying cause (i.e. infection, cancer, inflammatory bowel disease, etc.) is the primary concern. Supportive care such as cool compresses on the lesions, anti-inflammatory medications and rest are sufficient to manage the skin lesions.

   A mnemonic to aid in remembering the causes and treatment for erythema nodosum includes the acronym “BEDREST.” This stands for Behçet’s syndrome, Estrogens, Drugs, Recent infection, Enteropathies, Sarcoidosis and Tuberculosis. Bed rest is also one of the treatments.

   Dr. Fishco is board-certified in foot surgery and reconstructive rearfoot and ankle surgery by the American Board of Podiatric Surgery. He is in private practice in Phoenix. He is also a faculty member of the Podiatry Institute.

   Dr. Fishco pens a monthly blog for Podiatry Today. For more info, visit .

   For further reading, see “When A Patient Presents With A Pruritic Lower Extremity Rash” in the April 2011 issue of Podiatry Today or “A Guide To Skin Conditions Of The Diabetic Foot” in the September 2004 issue.

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