Zovirax 400 Mg

Last Updated on 07/28/2026 ✔ Medically Reviewed by Dr. Arjun Srivastav

What Is Zovirax 400 mg?

Zovirax 400 mg is an antiviral medication available by prescription in the form of a tablet containing 400 mg of Acyclovir. It is manufactured by GlaxoSmithKline Pharmaceuticals Ltd. Zovirax 400 can be prescribed for treating infections caused by viruses belonging to the herpes virus family, such as genital herpes, cold sores, shingles (herpes zoster), and chickenpox (varicella) as part of comprehensive viral care.

Acyclovir works by slowing the multiplication of the virus in the body, which can help reduce the duration and severity of symptoms when treatment is started early. Zovirax 400 mg does not remove the virus from the body, but it can help manage outbreaks and support the healing of sores.

Doctors may prescribe Zovirax 400 mg for both first-time and recurrent herpes infections, depending on the type of infection, the patient’s health condition, and the recommended treatment plan.

How Does Zovirax 400 mg Work?

Zovirax 400 mg works by interfering with the way herpes viruses reproduce inside infected cells. After the tablet is absorbed, Acyclovir is converted into its active form within virus-infected cells.

The medicine blocks an enzyme known as viral DNA polymerase, which the virus requires to make copies of itself. As viral replication slows, the infection becomes easier for the immune system to control.

Although Zovirax helps manage active herpes infections, it does not eliminate the virus from the body. The virus can remain inactive in nerve cells and may reactivate later in some people.

Medical studies indicate that early treatment may help reduce the duration and severity of symptoms associated with herpes virus infections.

How Does Acyclovir Stop Viral Replication?

Acyclovir targets cells infected with the herpes virus while having minimal effect on healthy cells. Its action includes:

• Preventing the virus from copying its genetic material.
• Slowing the spread of infection to nearby cells.
• Helping existing sores heal over time.
• Supporting the body’s natural immune response.

This targeted action makes Acyclovir a widely used antiviral medicine for herpes-related infections.

When Does Zovirax 400 mg Start Working?

Zovirax begins working after it is absorbed into the bloodstream, but noticeable symptom improvement usually takes a little longer. The time may vary depending on:

• The type of viral infection
• How early treatment is started
• Individual response to the medicine
• Overall immune health

Clinical guides suggest beginning treatment as soon as symptoms appear, as early use is generally associated with better symptom control and shorter outbreaks.

What Is Zovirax 400 mg Used For?

Zovirax 400 mg is prescribed to treat infections caused by the herpes virus family. Its active ingredient, Acyclovir, slows the multiplication of the virus, helping the body control the infection and reducing the severity and duration of symptoms when treatment is started early.

Doctors may prescribe Zovirax 400 mg for both first-time and recurrent herpes infections. The dosage and length of treatment depend on the type of infection, the patient’s age, overall health, and the response to treatment.

Zovirax 400 mg is commonly used for:

• Genital herpes (HSV-2): Helps manage outbreaks, supports the healing of sores, and may reduce discomfort.
• Cold sores (HSV-1): May shorten the duration of sores around the lips and mouth when treatment begins at the first signs of symptoms.
• Shingles (Herpes zoster): Helps slow viral activity and supports recovery when started soon after the rash appears.
• Chickenpox (Varicella): May be prescribed for certain adults and children under a doctor’s supervision.
• Recurrent herpes infections: May be used as part of a long-term treatment plan to help reduce the frequency of outbreaks in people who experience repeated episodes.

Available Strengths

Zovirax tablets are available in multiple strengths to support different treatment plans. The appropriate strength depends on the infection being treated, its severity, and your healthcare provider’s recommendation.

Available strengths include:

Benefits of Zovirax 400 mg

Zovirax 400 mg has been widely used for many years in the management of herpes virus infections. Medical research and clinical treatment guidelines indicate that starting antiviral therapy early may improve treatment outcomes for eligible patients.

Depending on the infection being treated, Zovirax 400 mg may offer the following benefits:

• Helps Slow Viral Replication: Acyclovir works by limiting the virus’s ability to multiply, helping reduce the spread of infection within the body.
• Supports Faster Healing of Skin Lesions: Treatment may help existing blisters and sores heal sooner compared with leaving the infection untreated.
• May Reduce the Severity of Symptoms: Many patients experience less discomfort, burning, itching, or pain as the infection begins to improve.
• Helps Lower the Formation of New Lesions: During active outbreaks, antiviral treatment may reduce the appearance of additional sores.
• Useful for Recurrent Herpes Management: For people who experience frequent herpes outbreaks, healthcare providers may prescribe Zovirax as part of an ongoing treatment strategy.
• Suitable for Multiple Herpes Virus Infections: Unlike medicines intended for a single condition, Zovirax 400 mg is commonly prescribed for several herpes virus infections, including: Genital herpes, Cold sores, Shingles, Chickenpox.

Zovirax 400 mg Dosage Guide

The dose of Zovirax 400 mg depends on the type of infection, age, kidney function, and overall health. Always take this medicine exactly as prescribed. Do not change the dose or stop treatment without your doctor’s advice, even if your symptoms improve.

How to Take Zovirax 400 mg

For proper use, follow these instructions:

• Swallow the tablet whole with a glass of water.
• Take it with or without food.
• Take each dose at the same time every day.
• Complete the full course, even if you start feeling better.
• Do not crush, chew, or split the tablet unless your doctor tells you to do so.
• Drink enough fluids during treatment.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take two doses at the same time to make up for a missed one.

Overdose

Taking more than the prescribed dose may increase the risk of side effects. Possible symptoms include:

• Nausea or vomiting
• Headache
• Confusion
• Agitation
• Reduced urination
• Kidney problems in severe cases

If you think you have taken too much, contact your doctor or seek emergency medical care immediately.

Possible Side Effects of Zovirax 400 mg

Like all pills, Zovirax 400 mg (Acyclovir) may cause side effects, although not everyone experiences them. Most side effects are mild and usually go away as your body adjusts to the medicine.

If any side effect becomes severe, does not go away, or you notice unusual symptoms, contact your doctor promptly.

Who Should Avoid Zovirax 400 mg?

Zovirax 400 mg may not be suitable for everyone. Tell your doctor about your medical history and any medicines or supplements you are taking before starting treatment. Talk to your doctor before taking Zovirax 400 mg if you:

• Are allergic to Acyclovir, Valacyclovir, or any ingredient in the tablet.
• Have kidney disease or reduced kidney function.
• Are dehydrated or unable to drink enough fluids.
• Have a weakened immune system.
• Are pregnant, planning to become pregnant, or breastfeeding.
• Take medicines that may affect kidney function.
• Have had an allergic reaction to antiviral medicines in the past.
• Are an older adult, as your dose may need adjustment based on kidney function.

Some medicines may affect how Zovirax 400 mg works or increase the chance of side effects. Tell your doctor about all prescription medicines, over-the-counter products, vitamins, and herbal supplements you are taking before starting treatment.

Safety Advice When Taking Zovirax 400 mg

Following simple safety measures can help support appropriate use of Zovirax 400 mg throughout your treatment. Medical guides recommend taking the medicine exactly as prescribed and informing your healthcare provider about any existing medical conditions before starting therapy.

Heart Conditions

No specific heart precautions are generally required, but tell your doctor if you have a heart condition or take heart medicines.

Kidney

Dose adjustment may be needed in people with kidney problems, and staying well hydrated is recommended.

Alcohol

No known direct interaction exists, but alcohol may increase dizziness or dehydration in some people.

Pregnancy & Breastfeeding

Use during pregnancy or breastfeeding only after discussing the benefits and risks with your doctor.

Driving & Machinery

Avoid driving or operating machinery if you experience dizziness, headache, or drowsiness.

Children

Children should take Zovirax only under a doctor's supervision, with the dose based on age and body weight.

Storage and Disposal

Proper storage ensures the quality of Zovirax 400 mg during the period of storage.

• Store at room temperature, protected from excessive heat and humidity.
• Maintain the medication in its original container until it is taken.
• Prevent the medicine from exposure to direct light.
• Store away from the reach of children and pets.
• Do not take the medicine after its expiry date mentioned on the packaging.
• Do not flush tablets down household plumbing or toilets except when required by local guidelines.

Zovirax 400 mg contains Acyclovir, an antiviral drug used to treat viral herpes infections, including genital herpes, cold sores, shingles, and chickenpox.

When buying Zovirax 400 mg, you have the option to select a reliable online pharmacy such as AustraliaRXMeds. However, before taking this medication, it is important to know all about it.