First-lineValtrex
Valaciclovir
Prodrug of aciclovir
Better bioavailability for genital HSV suppression in late pregnancy.
Oral
First-line for
- Genital HSV suppression from 36/40 (recurrent or 1° episode in pregnancy)
- HSV episodic treatment
Mechanism
Prodrug hydrolysed to aciclovir → DNA polymerase inhibition in HSV-infected cells.
“Suppress from 36/40”
- First-episode HSV in T3 → consider LSCS
- Recurrent HSV → vaginal delivery + suppression
Dosing
- Suppression (≥36/40)
- 500 mg BD until delivery
- Episodic
- 500 mg BD x 3 d
Contraindications
- CautionRenal impairment — dose adjust
- AbsoluteAciclovir/valaciclovir hypersensitivity
Side effects
- Headache, nausea
- TTP/HUS (rare, immunocompromised)
Fetal & maternal notes
- • Safe across pregnancy (large registry data)
- • Compatible with breastfeeding
Key interactions
Probenecid
Caution↑ levels
Nephrotoxins
Caution↑ AKI
Clinical pearls
- 💡 Reduces clinical HSV recurrence and asymptomatic shedding at delivery
- 💡 Cochrane: ↓ caesarean for HSV
Content last reviewed: REPLACE_ME (e.g. 2026-07)
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