Aciclovir prodrug
Valaciclovir
Brand names: Valtrex
Adult dose
Dose: Herpes zoster: 1g PO TDS x7 days. HSV: 500mg BD x5-10 days. CMV prophylaxis (transplant): 2g QDS
Route: PO
Frequency: per indication
Dose adjustments
Renal
Reduce per CrCl
Clinical pearls
- HSV genital/orolabial, herpes zoster, CMV prophylaxis
- Better PO bioavailability than aciclovir
Contraindications
- Hypersensitivity to aciclovir / valaciclovir
- Severe immunosuppression with high-dose (TTP/HUS risk)
Side effects
- Headache
- GI upset
- Renal impairment
- Neurotoxicity (esp. renal impairment)
- Thrombotic microangiopathy (high-dose, immunocompromised)
Interactions
- Probenecid
- Cimetidine
- Mycophenolate
Monitoring
- U&E
- Hydration
Reference: BNF; NICE NG147/CKS; https://bnf.nice.org.uk/drugs/valaciclovir/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Pathways
- Infective Endocarditis · ESC 2023 Infective Endocarditis Guidelines; NICE NG41
- Eczema Herpeticum · BAD; NICE CKS
- Suspected Bacterial Meningitis (Adult) · NICE NG240 (2024); NICE NG143 (paeds)
- Clostridioides difficile Colitis · NICE NG199 (2021); IDSA/SHEA 2021
- Returning Traveller — Fever · NaTHNaC; PHE; ESCMID 2018
- Malaria — Diagnosis & Management · PHE 2016; WHO 2023