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Acute Pain | Chronic Pain | General

Primary care treatment for postherpetic neuralgia in acute herpes zoster

Clinical bottom line: There is no convincing evidence that antiviral or corticosteroid treatment reduces postherpetic neuralgia. A ten day course of acyclovir is associated with a modest improvement at three months after onset of acute rash. This improvement may not be clinically relevant. Better quality trials are required to provide definitive answers.

This has been defined as pain persisting in the dermatomes affected by herpes zoster (shingles) after the disappearance of the rash caused by the infection.

Up to 15% of untreated patients have persistent pain one month after healing of an acute herpetic rash. One quarter of these (about 4% of total) still have pain at one year. The risk of postherpetic neuralgia increases sharply with age, and can be as high as 50% in patients aged over 60 years and 75% in those aged over 75 years.

There is no consensus on how acute herpes zoster (shingles) should be managed in general practice. Treatment of the acute rash can include antiviral agents and corticosteroids.

Systematic review

Lancaster T, Silagy C, Gray S. Primary care management of acute herpes zoster: systematic review of evidence from randomised controlled trials. Br J Gen Pract 1995; 45:39-45.

Inclusion criteria were randomized controlled trials of posthepetic neuralgia in acute herpes zoster; general-practice orientated treatments; pain outcomes at one (and preferably three and six) months.

Pain data were extracted. Expected event rates were subtracted from observed event rates for each trial. Estimate of effect size was calculated using odds ratios with 95% confidence intervals.

Findings

Twenty-one trials were found on acyclovir, other antiviral agents and corticosteroids.

Acyclovir vs. placebo

Eight trials were included in the analysis (seven oral and one topical). No statistically significant pain relief was detected at one or six month with odds ratios of 0.85 (0.61-1.19) and 0.70 (0.47-1.06) respectively. However, at three months the pain relief was significant, with an odds ratio of 0.65 (0.46-0.93). When data were analysed again with just high dose trials, the results were the same. Reviewers assessed the clinical relevance of the positive finding which suggests that acyclovir reduces postherpetic neuralgia by 30%. The number of patients who would have to receive a course of treatment to prevent one developing postherpetic neuralgia is 15.

Idoxuridine vs. placebo

Three trials compared topical idoxuridine with placebo. Quality of trials was relatively low. Two of three trials showed pain relief at one month. None of the three trials showed pain relief at six months.

Other antiviral comparisons

Trials were not of sufficient quality or power to provide useful data.

Corticosteroids vs. placebo

Four trials compared corticosteroids (predominantly prednisolone) with placebo. Findings were mixed, and quality of trials was poor. It is not, therefore, possible to interpret findings.


Adverse effects

Adverse effects of acyclovir were considered minor, including headache and nausea, and incidence was similar to control.

Further references

This review examines evidence for sympathetic ganglionic block to prevent postherpetic neuralgia:

These four systematic reviews are all covered by the current review:

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