What causes erythema nodosum?

The condition produces tender, warm nodules, most often over the shins. It is a reaction pattern rather than a single disease, so the visible lumps do not identify one cause by themselves. Recent throat or other infections, inflammatory bowel disease, sarcoidosis, some medicines, and pregnancy can be associated with it. Sometimes no underlying trigger is found. A clinician may review your recent illness, medicines, symptoms outside the skin, and examination findings before deciding whether tests are useful.

Arrange an assessment if the lumps are new, recurring, or accompanied by fever, joint pain, cough, diarrhoea, or abdominal symptoms. Bring a list of prescription medicines, supplements, and recent infections. Do not stop a prescribed medicine without advice. Treatment may focus on the trigger and on easing inflammation; an oral corticosteroid may be considered when a clinician feels it is appropriate. Read more about [Oral Corticosteroid Treatment](/treatments/medical-dermatology/oral-corticosteroid-therapy/).

Seek prompt medical care for rapidly worsening redness, severe pain, high fever, breathing difficulty, faintness, or a swollen leg. These features can point to a problem needing urgent assessment and should not be explained away as erythema nodosum.

Could an infection, medicine, inflammatory condition, or pregnancy be contributing? Do my other symptoms suggest testing? Which pain-relief options fit my health history? What changes should make me contact the clinic sooner?