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 generally not 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 eradicate these viruses from the body, but it can help symptoms improve faster when taken as prescribed.

Prescription medication: 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 multiple dosage forms. Do not mix instructions between 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 |
Labeled use |
| Oral acyclovir (tablets/capsules/suspension) |
Taken by mouth |
When systemic treatment is needed (e.g., shingles, chickenpox, genital herpes) |
Shingles, genital herpes (initial/recurrent), chickenpox |
| Zovirax Cream 5% |
Applied to affected area on the lips/face only (not in eyes, mouth, nose, or 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 skin (cutaneous use; not in 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 key difference is the dosage form and available strengths, which affects convenience (how many units you need per day).
For example, an 800 mg dose can reduce pill count compared with taking multiple 200 mg units.
When 800 mg is used
Oral acyclovir 800 mg is commonly used in labeled regimens for shingles (herpes zoster) and chickenpox (varicella). Your prescriber selects 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 (prodrug converted to acyclovir) |
| Dosing convenience |
Often more frequent dosing for some indications |
Often less frequent dosing for some indications |
| Cold sores (herpes labialis) |
Topical cream is the intended option; oral acyclovir may be used off-label if prescribed |
Oral valacyclovir has a labeled regimen for cold sores |
| Cost & availability |
Often lower-cost due to broad generic availability |
May be more convenient but can be higher cost depending on market |
Dosing table
The table below summarizes commonly referenced labeled regimens. If a form is not used or not labeled 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 sufficient quantity to cover all lesions every 3 hours (6 times daily) for 7 days |
| Limited mucocutaneous HSV in certain immunocompromised patients |
- |
- |
Apply sufficient quantity 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 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 double up unless directed.
Precautions
- Kidney disease / dehydration: higher risk of kidney-related side effects-your prescriber may adjust the dose.
- Drug interactions: tell your clinician about all medicines, including OTC and supplements. Some drugs can affect kidney function.
- Pregnancy/breastfeeding: discuss risks and benefits with your clinician.
Possible side effects
Side effects vary by person and 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 68°F to 77°F (20°C to 25°C); excursions permitted between 59°F to 86°F (15°C to 30°C).
- Protect from moisture and keep out of reach of children.
- Do not use after the expiry date on the carton.