First-lineZovirax
Aciclovir
Nucleoside analogue (HSV/VZV)
Genital herpes & VZV exposure in pregnancy — safe.
OralIVTopical
First-line for
- Primary/recurrent genital HSV
- Suppression from 36/40 if HSV in pregnancy
- VZV in pregnancy
Mechanism
Viral thymidine kinase activates → DNA chain terminator.
Aciclovir doses
- P — Primary 400 mg TDS ×5 d
- S — Suppression 400 mg TDS from 36/40
- V — VZV 800 mg 5×/day ×7 d
Dosing
- Primary HSV
- 400 mg PO TDS ×5 days
- Suppression
- 400 mg PO TDS from 36/40 until delivery
Contraindications
- CautionRenal impairment (dose-adjust)
Side effects
- Nausea, headache
- Crystalluria / AKI (IV)
- Neurotoxicity at high dose
Fetal & maternal notes
- • Safe across all trimesters & lactation.
Key interactions
Nephrotoxics
Caution↑ AKI
Clinical pearls
- 💡 Primary HSV in T3 → elective LSCS.
- 💡 Recurrent — vaginal delivery acceptable + suppression.
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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