What is Erythema multiforme?

a cutaneous hypersensitivity reaction that is most commonly triggered by infections

What are the main clinical features of Erythema multiforme?

• target lesions
• initially seen on the back of the hands / feet before spreading to the torso
• upper limbs are more commonly affected than the lower limbs
• pruritus is occasionally seen and is usually mild

What are the main causes of Erythema multiforme?

• viruses: herpes simplex virus (the most common cause), Orf*
• idiopathic
• bacteria: Mycoplasma, Streptococcus
• drugs: penicillin, sulphonamides, carbamazepine, allopurinol, NSAIDs, oral contraceptive pill, nevirapine
• connective tissue disease e.g. Systemic lupus erythematosus
• sarcoidosis
• malignancy

What is Erythema multiforme major?

A more severe form of Erythema multiforme which also involves mucous membranes