Drug-induced hypersensitivity syndrome (DIHS) is characterized by fever, rash and internal organ involvement (e.g. hepatitis, nephritis), which may occur app. 1–8 weeks after medicine exposure. Fever is an early feature, usually preceding a widespread erythematous skin eruption, but the severity of the skin-related changes does not correlate with the extent of internal organ involvement.

It is considered that anticonvulsants, antibiotics, allopurinol are the most frequent causative agents of DIHS. The underlying mechanisms causing DIHS are poorly understood - defective detoxification of the reactive drug’s metabolites and genetic predisposition and have been implicated. Diagnosis of DIHS is based on clinical presentation connected with drug intake, supported by a finding of eosinophilia and abnormal internal organs test, mainly liver function tests. Treatment consists of immediate withdrawal of all suspect medicines, followed by supportive systemic corticosteroids.