Erythema Nodosum

Who's At Risk?

Erythema nodosum can develop in persons of any age, sex, and ethnicity. Young adults are particularly susceptible to developing erythema nodosum. Moreover, women are 4 times more likely than men to be affected.

Approximately 30–50% of cases of erythema nodosum have no underlying cause. However, an associated medication, infection, or health condition may be found in the remainder of cases.

Erythema nodosum may develop in people on these medications:

• Birth control pills
• Estrogen pills
• Antibiotics (such as sulfonamides or penicillin)

Erythema nodosum may occur in persons with one of the following infections:

• Streptococcal infections (such as strep throat)
• Intestinal infections
• Tuberculosis
• Pneumonia (viral or bacterial)
• Fungal infections (such as coccidioidomycosis or histoplasmosis)

Erythema nodosum may be seen in individuals with one of these underlying medical conditions:

• Pregnancy
• Inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
• Sarcoidosis
• Lymphoma or leukemia

Signs & Symptoms

The most common locations for erythema nodosum include:

• Shins
• Knees, ankles, or thighs
• Forearms
• Face and neck

Erythema nodosum appears as one or more reddish, warm, and painful lumps or nodules, ranging in size from 1–10 cm.

The onset of erythema nodosum may be associated with fever, generalized achiness, leg swelling, or joint pain.

Individual nodules of erythema nodosum usually last from 1–2 weeks, but new lesions may continue to appear for up to 6 weeks. When an individual lesion of erythema nodosum has resolved, it may leave behind a temporary bruise, which subsequently fades to normal-appearing skin.

Self-Care Guidelines

Although erythema nodosum may occur on its own, it is more often associated with a medication or with an underlying infection or medical condition. Therefore, it is important to see a physician in order to investigate any possible health problems. In the meantime, however, the tenderness of the skin lesions may be alleviated by the following:

• Restriction of physical activity or bed rest
• Elevation of the legs (if they are affected)
• Cool or warm compresses

Generally, people with erythema nodosum do quite well, especially once any underlying medical condition has been treated.

Treatments

After diagnosing you with erythema nodosum, your physician will attempt to identify a possible cause, such as medication, infection, or medical condition. The doctor may order diagnostic tests such as blood work, chest X-ray, or throat culture. If an underlying cause is identified, then the physician will treat it appropriately (for example, by discontinuing a medication, prescribing antibiotics for an infection, or treating a health problem).

Once those investigations and treatments are under way, your health care provider may try the following measures to make you more comfortable:

• Restriction of physical activity or bed rest
• Anti-inflammatory medications such as ibuprofen or aspirin
• Potassium iodide
• Steroids (either taken in pill form or injected directly into the lesions)

Visit Urgency

Since erythema nodosum can be associated with underlying infections or health problems, a physician should be consulted within a few days of noticing the skin lesions.

Trusted Links

• MedlinePlus: Skin Conditions
• MedlinePlus: Skin Infections
• Clinical Information and Differential Diagnosis of Erythema Nodosum

References

Bolognia, Jean L., ed. Dermatology, pp.724, 1455, 1552-1555. New York: Mosby, 2003.

Freedberg, Irwin M., ed. Fitzpatrick’s Dermatology in General Medicine. 6^th ed, pp.1056, 1059, 1849, 1934, 1944. New York: McGraw-Hill, 2003.