Synopsis
Differentiate recurrent herpes simplex from dermatomal zoster, recognise ocular, neurological and disseminated emergencies, sample appropriately and start time-sensitive antiviral treatment with renal and transmission safeguards.
- HSV typically causes recurrent grouped painful vesicles or erosions at a mucocutaneous site; zoster causes unilateral dermatomal pain followed by vesicles that usually do not cross the midline.
- Swab a fresh vesicle base for PCR when diagnosis is uncertain, disease is severe or genital, or the result changes infection-control or specialist decisions.
- Herpes zoster ophthalmicus, eye pain, photophobia or visual change requires same-day ophthalmic assessment; a normal-looking eye does not cancel symptoms.
- Offer oral antivirals within 72 hours of zoster rash onset to people aged 50 or older and to younger people with ophthalmic, non-truncal, moderate-to-severe or immunocompromised disease.
- Consider treatment up to seven days after onset when new vesicles continue or complication risk is high.
- Aciclovir for zoster is 800 mg five times daily for seven days; valaciclovir 1 g three times daily for seven days improves dosing convenience.
- Adjust aciclovir and valaciclovir for renal impairment, maintain hydration and review nephrotoxic medicines or new confusion.
- Keep lesions covered, avoid pregnant non-immune people, neonates and severely immunocompromised contacts, and exclude from susceptible-care settings while lesions remain weeping.
Key red flags
Ocular symptoms, Hutchinson sign, neurological deficit, meningism, disseminated lesions, eczema herpeticum, pregnancy near delivery with genital lesions, neonatal exposure or severe immunocompromise requires urgent specialist care.
Forehead, upper-eyelid or nasal-tip vesicles with eye symptoms indicates trigeminal involvement and possible intraocular disease.
Severe ear pain, vesicles in ear or palate, ipsilateral facial palsy, vertigo or hearing change needs urgent ENT and specialist antiviral care.
Sudden monomorphic painful punched-out erosions over eczema with fever or malaise requires same-day systemic antiviral assessment.
Widespread vesicles, confusion, seizure, meningism, focal deficit or visceral symptoms in herpesvirus infection is an emergency.
Investigation priorities
Distinguish herpes viruses in atypical, severe, genital or immunocompromised presentations.
Management branches
A unilateral dermatomal eruption is within 72 hours and age, severity, site or host risk meets antiviral criteria.
- Check eye, ear, neurological and dissemination features, pregnancy, immunity, renal function and medicines.
- Start aciclovir 800 mg five times daily or valaciclovir 1 g three times daily for seven days with renal adjustment and hydration advice.
- Provide stepped analgesia, cover lesions and review new vesicles, eye symptoms, weakness or uncontrolled pain promptly.