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. Rather, it is a sign of some other infection, disease, or of a sensitivity to a drug.

Diseases that can cause erythema nodosum

These diseases include:

• 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 or Crohn's disease

• Cancer

• Pregnancy

Medicines that can cause erythema nodosum

These medicines include:

• 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:

• Red, tender bumps 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 talk with your healthcare provider for a diagnosis.

How is erythema nodosum diagnosed?

A biopsy (removal of tissue for exam under a microscope) of a bump can usually confirm the diagnosis. The biopsy is done along with complete lab work. However, the exact cause cannot always be identified. Erythema nodosum caused by medicine can usually be diagnosed by elimination of the medicine 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 discussed with you by your healthcare provider based on:

• Your age, overall health, and medical history

• Extent of the condition

• Your tolerance for specific medicines, 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 medicines

• Oral corticosteroids

Although erythema nodosum is uncomfortable, it is usually not a serious condition. Symptoms are usually gone within 6 weeks. However, they may appear again.