Erythema nodosum

What are the aims of this leaflet?

This leaflet has been written to help you understand more about erythema nodosum. It tells you what it is, what causes it, what can be done about it, and where you can find out more about it.

What is erythema nodosum?

Erythema Nodosum (EN) is a skin condition that is characterised by painful red, rounded lumps which appear on the shins and around the ankles, and less commonly the thighs and forearms. It can occur at any age, in both sexes, and in anyone. These lumps tend to heal to leave a bruise-like appearance. EN is more common among females and is more frequently observed between the ages of 20 and 30 years.

What causes erythema nodosum?

In most patients, no cause or trigger can be identified. In some patients, a trigger can be identified. EN may sometimes be a sign of an underlying condition that needs to be identified.

What are the common causes of erythema nodosum?

The commonest causes of EN are:

  • Throat infection caused by bacteria called Streptococci
  • Medication: drugs that are known triggers for EN include the contraceptive pills and some antibiotics.
  • Sarcoidosis: This is a rare inflammatory disease which can affect any organ in the body, but most commonly involves the lungs, lymph glands and skin. Sarcoidosis is one of the more common triggers for EN in adults
  • Inflammatory bowel disease: patients with both ulcerative colitis and Crohn's disease may infrequently develop EN.
  • Pregnancy: Pregnancy can occasionally trigger EN.

Is erythema nodosum hereditary?

No, EN is not a hereditary disorder.

What are the symptoms of erythema nodosum?

Patients with EN may feel generally unwell with a temperature shortly before or at the same time as the lumps start to appear. There may also be aching and swelling of the joints, mainly knees, ankles and wrists. Aching of the legs and swelling of the ankles may last for several weeks after the lumps have appeared.

What does erythema nodosum look like?

EN starts as poorly defined red painful lumps. They feel like firm, smooth, raised lumps, 2 to 6 cm in diameter on the skin and are often very tender. They most typically appear on the shins and around the ankles. As the lump begins to fade, it looks more like a bruise, turning blue and then yellowish in white skin. The lumps usually clear over a period of 3–6 weeks without scarring.

How is erythema nodosum diagnosed?

The diagnosis is usually made by the doctor recognising the rounded lumps on the skin on the typical sites. Occasionally it is necessary for a skin biopsy to be done to confirm the diagnosis. This involves the removal of a small sample of skin under local anesthetic by the doctor in the hospital. This sample is then processed by the laboratory and then examined under the microscope. Additional investigations, usually blood tests and a chest x-ray, may be required to determine the underlying cause of EN.

Can erythema nodosum be cured?

Most patients with EN make a full recovery within a few weeks or months. However, in some patients, new lumps of EN may occur over several weeks, with the condition persisting and following a longer time course lasting for 6 months and occasionally longer.

How is erythema nodosum treated?

Your doctor will look for known triggers for EN. If an infectious cause is identified, then antibiotic treatment may be given. If a particular medication is suspected as the trigger, it may be stopped. For most people with EN the rounded lumps tend to heal spontaneously. Some patients may need treatment to relieve symptoms, such as bed-rest, leg elevation, and anti-inflammatory painkillers (non-steroidal anti-inflammatory agents). For more prolonged EN, a number of stronger treatments may be used such as steroid tablets.

Self-care (What can I do?)

There is not a great deal you can do to influence the course of EN other than elevating the legs when resting, and avoiding too much time standing, walking and running.

Where can I get more information about erythema nodosum?

Web links to detailed leaflets:

For details of source materials used please contact the Clinical Standards Unit (

This leaflet aims to provide accurate information about the subject and is a consensus of the views held by representatives of the British Association of Dermatologists: individual patient circumstances may differ, which might alter both the advice and course of therapy given to you by your doctor.

This leaflet has been assessed for readability by the British Association of Dermatologists’ Patient Information Lay Review Panel


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