Written by Clay Smith
Acyclovir within 72-hours of onset of herpes zoster did not reduce pain from post-herpetic neuralgia (PHN) better than placebo at 4 to 6-month follow up. But it likely helped with acute pain from zoster at 1-month.
Why does this matter?
PHN is common and can be debilitatingly painful. In patients > 50 years old, 40% will have PHN; 75% if ≥75 years old.
Acyclovir doesn’t work for PHN
This was a quick summary of a Cochrane review. When considering 6 RCTs with 1,211 patients, acyclovir (one trial with famciclovir) did not reduce the incidence of PHN more than placebo at 4 or 6-month follow up. Antivirals didn’t appear to have any adverse effects. However, they likely reduced acute pain from the initial infection at 1 month, 44.1% (153/347) acyclovir and 53.3% (184/345) placebo; RR 0.83, 95% CI 0.71-0.96, p=0.01). Given the benefit in reducing acute pain, I will likely still use an antiviral for acute zoster. Since antivirals don’t reduce PHN, this highlights the importance of prevention. The new inactivated, more efficacious recombinant zoster vaccine should be recommended to patients ≥ 50.
Antiviral Medications for the Prevention of Post Herpetic Neuralgia after Herpes Zoster Infection. Acad Emerg Med. 2018 Nov 12. doi: 10.1111/acem.13662. [Epub ahead of print]
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