Editorially reviewed by Dr Fatimah Khan, registered with the Pakistan Medical and Dental Council (PMDC no. 104595-P). Editorial medical reviewer; does not prescribe or review patient assessments.
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What is aciclovir used for?
Aciclovir, also spelled acyclovir, is an antiviral used for infections including genital herpes, cold sores, shingles and chickenpox. Tablets, creams and eye ointments have different uses. A cold-sore cream is not a substitute for treatment prescribed for genital herpes or an eye infection. The NHS aciclovir guide explains these formulation differences.
This guide focuses on understanding treatment choices, rather than providing a dose to copy. The product, infection, kidney function and individual circumstances affect the prescription.
Outbreak treatment versus daily suppression
| Approach | Purpose | Question for your clinician |
|---|---|---|
| Treatment of a first genital-herpes episode | Manage the initial illness | Which tests and follow-up are needed? |
| Episodic treatment | Treat a recurrence using an agreed plan | When should I start the prescribed course? |
| Daily suppressive treatment | Reduce recurrent symptomatic episodes | What benefit should I expect, and when will we review it? |
The CDC's 2021 STI guidance reports a 70–80% reduction in genital-herpes recurrence frequency with suppressive therapy among people with frequent recurrent HSV-2 episodes. This describes recurrence frequency, not a cure, an individual's guaranteed response, or a percentage reduction in partner transmission.
Antivirals do not eradicate latent herpes virus. Episodic treatment is most useful when started promptly under a clinician's existing instructions. Daily suppression and outbreak treatment use different regimens; do not transfer doses between them.
What about transmission?
Herpes can spread without visible symptoms. Avoiding sexual contact during symptoms and using condoms can reduce risk, but do not eliminate it. CDC cites specific transmission-reduction evidence for daily valaciclovir in certain heterosexual couples with different HSV-2 infection status. That finding should not be presented as an identical, proven transmission benefit for every aciclovir regimen or HSV type.
Discuss partner communication and prevention with a clinician rather than relying on medication alone.
Safety and practical use
Follow the leaflet for your exact formulation and the prescriber's directions. NHS guidance advises adequate water intake with tablets, particularly for people with kidney problems. Tell the clinician about kidney disease, pregnancy, breastfeeding and other medicines.
Tablets can cause headache, nausea, diarrhoea or dizziness; creams may cause local irritation. Reduced urination or other suspected serious effects need urgent medical advice. Difficulty breathing or throat swelling requires emergency help. This is not a complete adverse-effect list.
Getting reliable information
Bring the product name, strength and formulation to the review, together with a description of the episodes and all current medicines. Read our guide to online assessment and independent doctor review before choosing a service.
Prescrivia is a technology intermediary. Independent clinicians decide whether assessment, testing or treatment is appropriate; licensed pharmacies dispense medicines where applicable. Prescrivia does not diagnose, prescribe or guarantee access or outcomes.
General information only, not medical advice. Follow the leaflet for your actual product and discuss decisions with a qualified clinician. See the current clinical, legal and language review statuses for this edition.
Sources
- UK patient guidance on indications, formulations, kidney precautions and adverse effects; does not establish EU-wide access.
- US 2021 genital-herpes guidance: episodic versus suppressive therapy, recurrence reduction population, transmission evidence and limitations.
Sources checked online on 6 October 2026. UK and US guidance is identified as such; it does not establish availability or prescribing rules across all European countries.