Preliminary evidence suggests that
aciclovir can reduce the clearance of
theophylline (and therefore possibly aminophylline) by about 30%. Evidence for valaciclovir appears to be lacking although it would be expected to interact similarly.
Evidence appears to be limited. Be alert for an increase in the adverse effects of
theophylline (nausea, headache, tremor) if
aciclovir or valaciclovir is added, and consider monitoring
theophylline levels.