Drug-induced hypersensivity syndrome (DIHS) also called drug rash with eosinophilia and systemic symptoms (DRESS) is a severe multi-system drug reaction. It can be life-threatening due to the extent of internal organ involvement.

It may occur 2-6/8 weeks after medicine exposure.

Drugs more often reported to cause DIHS:

• anticonvulsivants (eg.phenytoin, carbamazepine, lamotrigine, valproic acid) 

• antimicrobials (vancomycin, antitubercolous drugs, , minocycline, nevirapine, dapsone, trimethoprim sulfamethoxazole)

• allopurinol

• biologics (eg, imatinib, efalizumab)

• nonsteroidal anti-inflammatory drugs ( eg, celecoxib, ibuprofen)

• quinine

• sulfasalazine,

• erythropoietin alfa,

• buproprion.

Diagnostic criteria for DIHS from RegiSCAR study group are (≥ 3 of the criteria marked with an asterisk are required for the diagnosis):

• hospitalization

• reaction to be sospected to be drug related

• acute rash * (the severity of the skin-related changes does not correlate with the extend of internal organ involvement)

• fever above 38°C *

• involvement of at least 1 internal organ *

• enlarged lymph nodes involving at least 2 sites *

• lymphocytes above or below laboratory limits *

• eosinophils above laboratory limits (in percentage or absolute count) *

• platelets below laboratory limits *

The main and most common features are:

• fever (≥ 38°C) (common early feature)

• cutaneous eruption (maculo-papular rash wich often progresses to exfoliative dermatitis. Sometimes papulopustular eruption)

• hepatitis

• lymphoadenopathy

• leucocytosis with eosinophilia and atypical lymphocytosis (increased number of atypical lymphocytes)

The pathogenesis of DIHS is likely to be multifactorial and include  first of all genetic factors and drug factors. Recently it has been postulated a virus-drug interactions. In fact there is serologic evidence of viral reactivations ( more frequent human herpesvirus 6 but also Epstein-Barr virus, cytomegalovirus, human herpesvirus 7) in DIHS, usually in patients with more severe organ involvement and with a poorer prognosis. But the increase in HHV-6 titres is detectable only late in the course of DIHS and will be helpful only in supporting the diagnosis of DIHS retrospectively.

Treatment consists of:

• immediate withdrawal of suspected medicine

• supportive care of symptoms

• systemic corticosteroids