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Therapeutic Approach

Erythema nodosum is a septal panniculitis classically located on the extensor surfaces of the lower extremities, usually presenting as discrete, erythematous, painful, nodules. Erythema nodosum generally arises as a reactive inflammatory process secondary to systemic disease; however, it may also appear as an idiopathic process. Due to the depth of involvement, topical therapies are not generally used. While erythema nodosum is often self-limited, therapy for persistent activity involves addressing the underlying systemic disease and anti-inflammatory therapy.

Erythema nodosum is generally a reactive condition and determining the underlying etiology is critical to ensuring disease resolution. The most common associations of the disease include inflammatory bowel disease (IBD), hormonal fluctuations often associated with oral contraceptive changes, streptococcal infection, sarcoidosis, and tuberculosis, but many less common etiologies are reported. The authors would recommend screening new patients with a complete blood count, fecal calprotectin, tuberculosis interferon release assay, anti-streptolysin-O and anti-DNAse-B titers, and chest x-ray at a minimum to identify the most common and critical underlying etiologies.

Concurrent with this evaluation, our recommended approach to erythema nodosum is below.

In the authors’ experience, ½ mg/kg prednisone tapered over 2 weeks or 500 mg twice daily of naproxen offer rapid disease and symptom control while evaluating for an underlying etiology. The ideal treatment afterwards is targeted treatment for the underlying disease. For recalcitrant disease or in patients for whom an underlying disease cannot be determined, naproxen is preferable to prednisone. At the time of this writing super-saturated potassium iodide (SSKI) can be challenging for pharmacies and patients to find at an affordable price, but is highly successful in recalcitrant patients. If using SSKI, dosing should be titrated, typically with an increase by 1 drop three times per day in orange juice to mask the associated metallic taste until the disease is controlled. Dapsone represents a long-term disease control option however, if the patient continues to suffer from disease, a more thorough and in-depth evaluation is necessary to evaluate for underlying comorbidities. See Table 59-1.

Table 59-1Erythema Nodosum Treatment Table

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