Oral acyclovir in the treatment of adult varicella.

An open study was conducted to evaluate the efficacy of oral acyclovir in a group of 295 Singapore Armed Forces male servicemen. The 148 patients who were willing to take acyclovir were given 800 mg orally five times per day for seven days. The other 147 who refused to take acyclovir were monitored as a control group. Each of these groups was further classified into two groups. Group A patients presented with rash within 24 hours of rash onset and Group B presented between 24 and 72 hours. Daily lesion counts, temperature, pruritus scores and laboratory tests were used to monitor disease progression. Early acyclovir intervention (Group A) reduced the time to 100% crusting from 7.19 to 5.71 days (P = 0.0001), decreased the maximum number of all lesions by 26% (P = 0.03) and the maximum number of vesicular lesions by 45% (P = 0.0004). Late therapy (Group B) was effective in reducing the maximum number of vesicular lesions by 38% (P = 0.003). The number of patients requiring antibiotics for suspected secondary skin infection, the duration of fever and paracetamol consumption were significantly reduced in both the early and late intervention groups. However, there were no effects in minimizing pruritus in either group. Serious complications such as pneumonia, encephalitis or death were not observed in this study. The most common adverse effect of acyclovir was mild diarrhoea occurring in 35% of patients treated with the drug. We conclude that early treatment with acyclovir was beneficial whereas late therapy had limited effect in reducing the severity of cutaneous lesions in patients with varicella.