Aciclovir — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Aciclovir?
Aciclovir is an antiviral medicine used to treat herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections. This medication is funded by Pharmac for herpes infections.
What is Aciclovir Used For?
Aciclovir is used for genital herpes (primary and recurrent episodes, and long-term suppression), cold sores (herpes labialis), chickenpox (varicella), shingles (herpes zoster), and herpes encephalitis (IV high-dose).
How Does Aciclovir Work?
Aciclovir is selectively phosphorylated by the viral enzyme thymidine kinase in herpes-infected cells, then further converted to aciclovir triphosphate by cellular kinases. This active form inhibits viral DNA polymerase and is incorporated into viral DNA, terminating viral replication. Selectivity for infected cells means minimal toxicity to normal human cells.
How to Take Aciclovir
For oral herpes (cold sores): 200 mg five times daily or 400 mg three times daily for 5–10 days. For genital herpes: 200–400 mg five times daily for 5–10 days (primary); 400 mg twice daily for suppression. For shingles: 800 mg five times daily for 7–10 days (start within 72 hours of rash onset). Take with plenty of water; maintain good hydration.
Common Side Effects of Aciclovir
- Nausea
- Headache
- Dizziness
- Fatigue
- Rash
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Renal impairment (with high-dose IV use or inadequate hydration — ensure adequate fluid intake)
- Neurological effects at high doses (confusion, hallucinations, seizures — more common with IV therapy)
- Thrombocytopenia (rare)
Drug Interactions
Aciclovir may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Probenecid (reduces aciclovir renal clearance — increases levels)
- Mycophenolate (increased levels of both drugs)
New Zealand Prescribing Information
Aciclovir (200 mg, 400 mg, 800 mg tablets; 200 mg/5 mL suspension; 5% cream) is funded by Pharmac. Valaciclovir (Valtrex®) is a prodrug of aciclovir with better oral bioavailability, allowing twice-daily rather than five-times-daily dosing — also funded under Special Authority for genital herpes suppression. Starting treatment promptly (within 72 hours of rash onset for shingles, or as soon as possible for genital herpes) maximises efficacy.
Frequently Asked Questions
Can aciclovir cure herpes?
No — aciclovir suppresses viral replication but does not eliminate the latent virus. The herpes virus remains dormant in nerve ganglia and can reactivate. Long-term daily aciclovir (suppressive therapy) greatly reduces the frequency and severity of recurrences and reduces transmission risk.
Can I use the aciclovir cream for genital herpes?
Topical aciclovir cream (5%) is much less effective for genital herpes than oral aciclovir. Oral treatment is strongly preferred for genital herpes as it achieves adequate drug levels throughout the affected area and reduces healing time more effectively than topical application.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: