III. Antibiotics, antiviral, antifungal, drugs

Acyclovir is a structural analogue of guanosine which inhibits viral DNA-polymerase and is widely used as an antiviral drug in herpes and herpes-zoster infections.
Risk factors
Repeated topical use.
Clinical manifestations
Topical use: contact dermatitis.
Systemic administration: generalized eczema, vesicular eruption, phlebitis, urticaria.
Diagnostic methods
Cutaneous testing
Patch-tests with acyclovir 5% in water or pet. must be read at 30 min, 48 and 72 or 96 hours.
Some cases of sensitization are due to vehicle constituents (propylene glycol).
Delayed contact dermatitis.
Avoidance of acyclovir (topical and systemic) and valacyclovir. 


  1. Montoro J, Basomba A, "Fixed drug eruption due to acyclovir", Contact Dermatitis, 1997 ; 36: 225-31
  2. Goday J, Aguirre A, Gil-Ibarra N, Ezaguirre X, "Allergic contact dermatitis from acyclovir", Contact Dermatitis, 1991 ; 24: 380-1

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.