What are the recommended antiviral treatments for a patient diagnosed with herpes zoster, and when should they be initiated?

Recommended antiviral treatments for herpes zoster: The first-line antiviral treatments are oral aciclovir, valaciclovir, or famciclovir. Valaciclovir and famciclovir have shown superior efficacy in reducing herpes-zoster-associated pain compared to aciclovir, with valaciclovir reducing pain by 36% at 21-30 days and famciclovir reducing the risk of pain by 46% at 28-30 days. The choice of antiviral should consider dosing regimens, comorbidities, drug interactions, and costs, using a shared decision-making approach ¹.

For people who are severely immunocompromised or have complicated shingles, intravenous aciclovir is recommended. Intravenous therapy is also advised for those with disseminated infection, ophthalmic involvement, very severe immunosuppression, or inability to take oral medication ¹.

Timing for initiation: Antiviral treatment should ideally be started within 72 hours of rash onset. Treatment can be considered up to one week after rash onset, especially in people at higher risk of severe disease or complications, such as older age, immunocompromise, severe pain, or ongoing vesicle formation ¹.

Antiviral treatment is strongly recommended for immunocompetent people aged 50 years or over, those with moderate or severe pain or rash, non-truncal involvement, or predisposing skin conditions. It can also be considered in people at low risk of complications due to the safety profile of antivirals ¹.

In pregnancy or breastfeeding, specialist advice should be sought before prescribing antivirals, although aciclovir is the most commonly used and studied antiviral in pregnancy ¹.