What is it?
Erythema nodosum is a skin condition causing red, raised, tender nodules on the legs. They usually measure between 1 - 8cm.

What is the cause?
They tend to be associated with inflammatory bowel disease and are more common in Crohn's disease (up to 15%) than ulcerative colitis.

They tend to occur as the disease is active but may occasionally be the presenting symptom of the disease. It also occurs commonly with arthritis and inflammation of the eyes.

It tends to be more common in women and is also the commonest extra-intestinal symptom in children.

What is the treatment?
As the condition is associated with active disease, controlling the underlying disease will usually treat the skin lesions.