What should you know about erythema multiforme erythema nodosum?

Erythema multiforme typically causes raised target-like spots, often on the hands, arms, legs, or face, and may follow an infection or medicine exposure. Erythema nodosum causes tender, deeper lumps, most often on the fronts of the lower legs. It is an inflammatory reaction with several possible triggers. These names should not be treated as interchangeable, and a photograph or examination may be needed to distinguish them.

Record when the rash or lumps began, recent infections, new medicines, and whether the mouth, eyes, or genitals are affected. Avoid starting or stopping prescription medicine without advice. Depending on the findings, care may include treating a trigger, symptom relief, or [Topical Corticosteroids](/treatments/medical-dermatology/topical-corticosteroids/). Recurrent episodes linked with cold sores may prompt discussion of [Antiviral Treatment](/treatments/medical-dermatology/antiviral-therapy/).

Arrange prompt assessment for a new target-like eruption or painful leg lumps, especially if they are spreading or accompanied by fever. Seek emergency help for mouth or eye pain, difficulty swallowing or breathing, widespread blistering, skin peeling, or rapidly worsening illness. These features can indicate serious mucosal or skin involvement.

Which pattern do you see, and what triggered it? Do I need tests or a medicine review? How should I protect my eyes and mouth if they become involved?