How to reduce the pain of herpes zoster
Vesicles and crusts of herpes zoster on an erythematous base
Under the sponsorship of the International Society for the Study of Pain, an interdisciplinary group of physicians has developed Recommendations for the Management of Herpes Zoster—the first evidence-based, multispecialty consensus guidelines for the common condition, says Robert Dworkin, MD, who chaired the group.
With its diverse manifestations and complications, herpes zoster (HZ), aka shingles, may come to the attention of dermatologists, neurologists, ophthalmologists, infectious disease specialists, and pain specialists. But it is often diagnosed and first treated in primary care.
A dominant theme of the document is the importance of reducing pain, observes Dr. Dworkin, professor of anesthesiology, neurology, oncology, and psychiatry at the University of Rochester in New York. “Clinicians should attend to pain for two reasons: Pain while the patient still has a rash is a clinical concern in its own right; it has a negative impact on quality of life and on physical and emotional function and needs to be reduced to the extent possible. Secondly, there are reasons to hypothesize that controlling the acute pain of zoster will lessen the risk of chronic pain.”
Antiviral therapy—start it quickly
Most patients should start taking an antiviral medication as soon as possible (see Figure 1). This is “the main take-home message of the Recommendations,” says Dr. Dworkin. Randomized controlled trials have repeatedly demonstrated that these agents shorten the period of acute pain and hasten resolution of the rash. The evidence that treatment forestalls postherpetic neuralgia (PHN) is also strong, although less conclusive.
Three antivirals—acyclovir, famciclovir, and valacyclovir—have been approved by the FDA for treating HZ. The Recommendations note that the latter two agents appeared more efficacious than the first in clinical trials and that their more convenient dosing schedule (three times vs. five times daily) probably fosters superior compliance.
Based on clinical trial data and product labeling, the authors advocate systemic antivirals as first-line treatment for HZ in immunocompetent patients who are aged 50 or older, who have moderate-to-severe pain or rash, or whose lesions appear in places other than the trunk.
In light of the exceptional safety of these medications, however, the authors also suggest that antiviral treatment be considered even for patients who satisfy none of these criteria.
Similar logic applies to treatment timing. Controlled clinical trials have all initiated antiviral therapy within 72 hours of rash onset; its efficacy when started later is unproven. “But there's nothing magical about 72 hours—it's somewhat arbitrary as an inclusion criterion,” Dr. Dworkin notes.
Especially in light of the “minimal risks” of these drugs and the fact that diagnosis and acquisition of medication are often delayed, the authors recommend that physicians consider initiating treatment even after 72 hours if new vesicles continue to form (suggesting ongoing viral replication); cutaneous, neurologic, or ocular complications have developed; or pain is severe.
Similarly, labeling calls for a seven-day course of famciclovir or valacyclovir, and the efficacy of extending treatment is unknown. But the potential for further benefit with little risk justifies this extended approach for patients who have new vesicles or cutaneous complications after the first week. (Close monitoring and possibly further evaluation are also indicated, the Recommendations say.)