| Jackson JL et al, 1997, USA | 5 placebo controlled randomised clinical trials. All trials used acyclovir 800 mg 5 times daily within 72 h of onset | Meta-analysis | Pain at 6 months | Summary odds ratio 0.54 (0.36, 0.81) in patients treated with acyclovir | |
| Whitley RJ et al, 1998, USA | 6 randomised controlled double blind studies | Meta-analysis | Factors influencing duration of pain | Age, prodromal pain, acute pain intensity | No separate data for trials 1–3. |
| Trials 1 to 3 compared oral acyclovir with placebo. | | Factors not influencing duration of pain | Sex, time from rash onset to initiation of treatment | |
| Wood MJ et al, 1998, UK | 3 placebo controlled studies or oral acyclovir. All trials used acyclovir 800 mg 5 times daily. | Meta-analysis | Resolution of zoster related pain in: | | |
| | | All patients | Hazard ratio 1.79 (1.43, 2.39) | |
| Early (<48 h) v late (48–72 h) treatment | | Patients over 50 y | Hazard ratio 2.13 (1.42, 3.19) | |