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Herpes zoster — MSRA MCQ

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ModerateInfectious DiseasesHerpes zosterMSRA

A 69-year-old man presents with a painful unilateral vesicular rash over the left lower thorax. The rash began 5 days ago and new vesicles have continued to appear today. He has moderate neuropathic pain despite regular paracetamol. He is afebrile and systemically well, with no ocular, auricular, neurological or disseminated features. He has stage 4 chronic kidney disease; his calculated creatinine clearance is 22 mL/minute. He is not immunosuppressed and can take oral medication. What is the most appropriate management today?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Prescribe oral aciclovir 800 mg three times daily for 7 days

Explanation lettering: D = shown as A · E = shown as B · A = shown as D · B = shown as E

This is uncomplicated herpes zoster presenting beyond 72 hours, but antiviral treatment remains appropriate because he is older and has continued new vesicle formation at day 5, both features associated with a higher risk of severe or complicated disease. UK antimicrobial guidance advises considering an antiviral up to 1 week after rash onset in this setting. The usual oral aciclovir regimen for herpes zoster is 800 mg five times daily for 7 days. However, his creatinine clearance is 22 mL/minute, within the 10–25 mL/minute range for which the SmPC recommends reducing the zoster regimen to 800 mg three times daily. Adequate hydration and monitoring for neurotoxicity are also important. A is inappropriate because the late presentation alone does not exclude treatment when new lesions are forming in an older patient. B is the standard regimen for normal renal function and risks accumulation in this patient. C is the dose adjustment for severe renal impairment with creatinine clearance below 10 mL/minute. E would be appropriate for severe immunocompromise, impaired gastrointestinal absorption, disseminated disease, or suspected neurological/visceral complications, none of which is present.

Reference: Varicella zoster/chicken pox - Herpes zoster/shingles (Antimicrobial) (2024) — https://www.rightdecisions.scot.nhs.uk/tam-treatments-and-medicines-nhs-highland/adult-therapeutic-guidelines/antimicrobial-guidance/skin-soft-tissue-antimicrobial/varicella-zosterchicken-pox-herpes-zostershingles-antimicrobial/ Aciclovir 800mg Tablets - Summary of Product Characteristics (14 April 2026) — https://www.medicines.org.uk/emc/product/2351/smpc