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.
Repeated topical use.
Topical use: contact dermatitis.
Systemic administration: generalized eczema, vesicular eruption, phlebitis, urticaria.
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.