Zovirax is also available as
Zovirax Cream 5% (5 g tube). For cold sores (herpes labialis) on the lips, the topical cream is the intended option; oral tablets/capsules are not usually the standard choice for this use.
About Zovirax (Acyclovir)
Acyclovir is an antiviral medicine used to help treat infections caused by herpes viruses, including herpes simplex viruses (HSV) and varicella-zoster virus (VZV). It works by slowing the growth and spread of the virus. Acyclovir does not clear these viruses from the body, but it can help symptoms improve more quickly when taken as prescribed.

Prescription-only medicine: Use only as directed by a licensed clinician.
What oral acyclovir tablets/capsules are used for
- Shingles (herpes zoster)
- Genital herpes (initial and recurrent episodes)
- Chickenpox (varicella)
Zovirax is available in different forms
The brand name Zovirax (acyclovir) and generic acyclovir may be available in several dosage forms. Do not mix up the instructions for different forms.
- Oral: tablets, capsules and oral suspension
- Topical: cream 5% and ointment 5%
- IV (hospital use): acyclovir for injection (intravenous)
Important: This product page is for oral acyclovir (tablets/capsules). Topical products (cream/ointment) and IV acyclovir have different directions for use.
When to use tablets vs cream vs ointment
| Form |
Where/how it's used |
When it's typically chosen |
Labelled use |
| Oral acyclovir (tablets/capsules/suspension) |
Taken by mouth |
When treatment throughout the body is needed (for example, shingles, chickenpox or genital herpes) |
Shingles, genital herpes (initial/recurrent), chickenpox |
| Zovirax Cream 5% |
Applied to the affected area on the lips/face only (not in the eyes, mouth, nose or on the genitals) |
For recurrent cold sores/fever blisters; start as early as possible |
Recurrent herpes labialis (cold sores) in immunocompetent adults and adolescents ≥12 |
| Zovirax Ointment 5% |
Applied to the skin (cutaneous use; not in the eyes) |
For certain HSV skin or mucosal outbreaks when this form is specifically prescribed; not recommended for routine cold sores on the lips |
Initial genital herpes; limited mucocutaneous HSV in certain immunocompromised patients |
Why Zovirax comes as both tablets and capsules
Acyclovir has been available in different oral dosage forms. Historically, 200 mg was commonly supplied as capsules, while 400 mg and 800 mg were commonly supplied as tablets. The main difference is the dosage form and the strengths available, which can affect convenience (how many you need to take each day).
For example, an 800 mg dose can reduce the number of pills compared with taking multiple 200 mg units.
When 800 mg is used
Oral acyclovir 800 mg is commonly used in labelled regimens for shingles (herpes zoster) and chickenpox (varicella). Your prescriber will choose the dose and schedule based on the infection, age/weight, kidney function and clinical severity.
Zovirax vs Valtrex (acyclovir vs valacyclovir)
| Feature |
Zovirax / Acyclovir |
Valtrex / Valacyclovir |
| What it is |
Acyclovir (active antiviral) |
Valacyclovir (a prodrug converted to acyclovir) |
| Dosing convenience |
Often needs to be taken more frequently for some conditions |
Often needs to be taken less frequently for some conditions |
| Cold sores (herpes labialis) |
Topical cream is the intended option; oral acyclovir may be used off-label if prescribed |
Oral valacyclovir has a labelled regimen for cold sores |
| Cost & availability |
Often lower in cost because generic versions are widely available |
May be more convenient but can cost more depending on the market |
Dosing table
The table below summarises commonly referenced labelled regimens. If a form is not used or not labelled for a condition, it is shown as a dash.
| Condition |
Oral acyclovir (this product) |
Zovirax Cream 5% |
Zovirax Ointment 5% |
Cold sores
(herpes labialis) |
- (topical cream is the intended option for cold sores) |
Apply 5 times daily for 4 days
Start as early as possible. |
- |
Fever blisters
(same as cold sores) |
- |
Apply 5 times daily for 4 days |
- |
Chickenpox
(varicella) |
Adults / >40 kg: 800 mg 4 times daily for 5 days
Children ≥2 years: 20 mg/kg per dose 4 times daily for 5 days (max 800 mg per dose) |
- |
- |
| Initial genital herpes |
- |
- |
Apply enough to cover all lesions every 3 hours (6 times daily) for 7 days |
| Limited mucocutaneous HSV in certain immunocompromised patients |
- |
- |
Apply enough to cover all lesions every 3 hours (6 times daily) for 7 days |
How to take oral acyclovir
- Take exactly as prescribed. Your dose, schedule and duration depend on the infection and your kidney function.
- Stay well hydrated (especially important for older adults and people with kidney disease).
- If you miss a dose, follow your prescriber's instructions; do not take a double dose unless you have been told to.
Precautions
- Kidney disease / dehydration: this can increase the risk of kidney-related side effects, and your prescriber may adjust the dose.
- Drug interactions: tell your clinician about all medicines you take, including medicines bought without a prescription and supplements. Some medicines can affect kidney function.
- Pregnancy/breastfeeding: discuss the risks and benefits with your clinician.
Possible side effects
Side effects vary from person to person and can depend on the dose. Contact a clinician promptly if you develop signs of an allergic reaction (rash/hives, swelling of the face/lips/tongue, trouble breathing), severe confusion, hallucinations or seizures.
How to store oral acyclovir
- Store at 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C to 30°C (59°F to 86°F).
- Protect from moisture and keep out of the reach of children.
- Do not use after the expiry date on the carton.