What is erythema nodosum?

Erythema nodosum is characterized by tender, red bumps, usually found symmetrically on the shins. Up to 55 percent of cases have no clear identifiable cause. Sometimes, erythema nodosum is not a separate disease, but, rather, a sign of some other infection, disease, or of a sensitivity to a drug.

Diseases that can cause erythema nodosum:

• Streptococcal infections

• Sarcoidosis (inflammation of the lymph nodes and other organs)

• Coccidioidomycosis (infection of the upper respiratory tract and lungs)

• Histoplasmosis (an infectious pulmonary disease)

• Tuberculosis

• Psittacosis (a flu-like disease)

• Ulcerative colitis

• Cancer

• Pregnancy

Drugs that can cause erythema nodosum:

• Antibiotics containing sulfa or penicillin

• Bromides

• Iodides

• Oral contraceptives

What are the symptoms of erythema nodosum?

The following are the most common symptoms of erythema nodosum. However, each individual may experience symptoms differently. Symptoms may include:

• Raised bruises on the shins

• Fever

• Joint pain

• Enlarged lymph nodes in the chest

Young adults are particularly susceptible to erythema nodosum. The symptoms of erythema nodosum may resemble other skin conditions. Always consult your doctor for a diagnosis.

How is erythema nodosum diagnosed?

A biopsy (removal of tissue for examination under a microscope) of a bump can usually confirm the diagnosis along with comprehensive lab work. However, the exact cause cannot always be identified. Drug-induced erythema nodosum can usually be diagnosed by elimination of the drug causing the reaction. A throat swab may be done to check for strep infection. 

Treatment for erythema nodosum

Specific treatment for erythema nodosum will be determined by your doctor based on:

• Your age, overall health, and medical history

• Extent of the condition

• Your tolerance for specific medications, procedures, or therapies

• Expectations for the course of the condition

• Your opinion or preference

Treatment may include:

• Antibiotics to treat an underlying bacterial infection

• Treatment of other underlying cause

• Bed rest (to relieve pain)

• Nonsteroidal anti-inflammatory drugs 

• Corticosteroids

Although erythema nodosum is uncomfortable, it is usually not a serious condition. Symptoms are usually gone within six weeks; however, they may recur.