Common use
Zovirax is an antiviral medication which used to treat herpes infections of the skin, lip, and genitals; herpes zoster; and chickenpox. Zovirax stops viral replication, but it does not work in treating certain virus infections, such as the common cold.

Dosage and direction

Take it orally with or without food/milk. Commonly used dose is 200 mg every 4 hours, five times a day for ten days. If the herpes is recurrent, the recommended dose for adults is 400 mg two times a day for 1 year. Washing of your hands will help you to prevent passing the infection to others.
Note: this instruction presented here just for review. It’s very necessary to consult with your doctor before using. It help you to get best results.

Precautions

Avoid letting infected areas come into contact with other people. Do not touch your eyes after touching an infected area. Do not use without doctor’s permission if your medical history include: kidney disease or liver disease. Zovirax should not be used during pregnancy, becoming pregnant or lactating without doctor’s advice. Do not use Zovirax before breast-feeding without doctor’s advice.

Contraindications

Zovirax is not allowed in patients with kidney disorders. Also Zovirax is contraindicated in people who are hypersensitive to Zovirax, Acyclovir or similar drugs.

Possible side effect

They may include an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Also the most possible side effects include:
pain in your lower back;
urinating less than usual or not at all;
easy bruising or bleeding;
unusual weakness.
Less serious include:
nausea, vomiting, diarrhea, loss of appetite, stomach pain;
headache, feeling light-headed;
swelling in your hands or feet.
If you experience one of them stop using Zovirax and tell your doctor as soon as possible. Also consult with your doctor about any side effect that seems unusual.

Drug interaction

Zovirax interact with: probenecid (Benemid), Tizanidine, Varicella Virus Vaccine, Fosphenytoin, Phenytoin, Valproic Acid. Also note that interaction between two medications does not always mean that you must stop taking one of them. Usually it affects the effect of drugs, so consult  your doctor about their interactions.

Missed dose

If you forgot to take your dose in time, please do it as soon as possibe. But do not take if it is too late or almost time for your next dose. Do not take double or extra doses. Take your usual dose next day at the same time regularly.

Overdose

Symptoms of Zovirax overdose include: seizure (convulsions), hallucinations, and urinating less than usually or not at all. If you experience one of them or any unusual symptom, call your doctor immediately.

Storage

Store at room temperature between 59-77 degrees F (15-25 degrees C) away from light and moisture, kids and pets. Do not use after expiration term.

Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care advisor or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Please find the full description of Zovirax at Drugs.com and general information at Wikipedia