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Drugs and diseases reference index

Drugs reference index «Acyclovir»


Brand names: Zovirax

Why is Acyclovir prescribed?

Zovirax liquid, capsules, and tablets are used in the treatment of certain infections with herpes viruses. These include genital herpes, shingles, and chickenpox. This drug may not be appropriate for everyone, and its use should be thoroughly discussed with your doctor. Zovirax ointment is used to treat initial episodes of genital herpes and certain herpes simplex infections of the skin and mucous membranes. Zovirax cream is used for herpes cold sores on the lips and face only.

Some doctors use Zovirax, along with other drugs, in the treatment of AIDS, and for unusual herpes infections such as those following kidney and bone marrow transplants.

Most important fact about Acyclovir

Zovirax does not cure herpes. However, it does reduce pain and may help the sores caused by herpes to heal faster. Genital herpes is a sexually transmitted disease. To reduce the chance of infecting your partner, forgo intercourse and other sexual contact while you have sores or any other symptom.

How should you take Acyclovir?

Your medication should not be shared with others, and the prescribed dose should not be exceeded. You can take Zovirax with or without food.

Zovirax ointment should not be used in or near the eyes. To reduce the risk of spreading the infection, use a rubber glove to apply the ointment.

Zovirax cream should not be used in or near the eyes, or inside the nose or mouth. The medication can, however, be applied on the outside of the lips. Apply the cream with your fingers to clean, dry skin. Be sure to wash your hands before and after applying Zovirax cream, and avoid bathing or swimming afterward to prevent it from washing off. Do not cover the cold sore with a bandage or make-up unless your doctor approves.

  • If you miss a dose...Take it as soon as you remember. If it is almost time for your next dose, skip the one you missed and go back to your regular schedule. Never take 2 doses at the same time.

If you are using the ointment, apply it as soon as you remember and continue your regular schedule.

  • Storage instructions...Store Zovirax at room temperature in a dry place.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Zovirax.

  • Side effects may include:Diarrhea, general feeling of bodily discomfort, nausea, vomiting
  • Side effects of Zovirax ointment may include:Burning, itching, mild pain, skin rash, stinging, vaginal inflammation
  • Side effects of Zovirax cream may include:Allergic reactions, burning, dry or cracked lips, dry or flaky skin, eczema (inflamed, irritated patches of skin), hives, inflammation, itchy spots, stinging

Why should Acyclovir not be prescribed?

If you are sensitive to or have ever had an allergic reaction to Zovirax or similar drugs, you should not take Acyclovir. Make sure that your doctor is aware of any drug reactions that you have experienced.

Special warnings about Acyclovir

If you are being treated for a kidney disorder, consult your doctor before taking Zovirax. The drug has been known to cause kidney failure.

If you develop unusual bruising or bleeding under the skin, be sure to alert your doctor. It could signal a dangerous blood disorder.

Possible food and drug interactions when taking Acyclovir

If Zovirax is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Zovirax with the following:


Special information if you are pregnant or breastfeeding

Zovirax seems relatively safe during pregnancy. Nevertheless, it should be used only if its benefits outweigh the potential risk to the baby. If you are pregnant or plan to become pregnant, inform your doctor immediately. Zovirax appears in breast milk and could affect a nursing infant. If Acyclovir is essential to your health, your doctor may advise you to discontinue breastfeeding your baby until your treatment with Zovirax is finished.

Recommended dosage for Acyclovir


For Genital Herpes

The usual dose is one 200-milligram capsule or 1 teaspoonful of liquid every 4 hours, 5 times daily for 10 days. If the herpes is recurrent, the usual adult dose is 400 milligrams (two 200-milligram capsules, one 400-milligram tablet or 2 teaspoonfuls) 2 times daily for up to 12 months.

If genital herpes is intermittent, the usual adult dose is one 200-milligram capsule or 1 teaspoon of liquid every 4 hours, 5 times a day for 5 days. Therapy should be started at the earliest sign or symptom.

Ointment: Apply ointment to affected area every 3 hours, 6 times per day, for 7 days. Use enough ointment (approximately one-half inch ribbon of ointment per 4 square inches of surface area) to cover the affected area.

For Herpes Cold Sores

Apply Zovirax cream to the affected area 5 times a day for 4 days. Therapy should begin as soon as possible after the first sign of a cold sore such as a bump, tingling, redness, or itchiness.

For Herpes Zoster (Shingles)

The usual adult dose is 800 milligrams (one 800-milligram tablet or 4 teaspoonfuls of liquid) every 4 hours, 5 times daily for 7 to 10 days.

For Chickenpox:

The usual adult dose is 800 milligrams 4 times a day for 5 days.

If you have a kidney disorder, the dose will need to be adjusted by your doctor.


The usual dose for chickenpox in children 2 years of age and older is 20 milligrams per 2.2 pounds of body weight taken orally 4 times daily, for a total of 80 milligrams per 2.2 pounds, for 5 days. A child weighing more than 88 pounds should take the adult dose.

The safety and effectiveness of oral Zovirax have not been established in children under 2 years of age. However, your doctor may decide that the benefits of Acyclovir outweigh the potential risks. The safety and effectiveness of Zovirax ointment in children have not been established. Zovirax cream has not been studied in children less than 12 years old.


Your doctor will start you at the low end of the dosage range, since older adults are more apt to have kidney problems or other disease, or to be taking other medications.


Zovirax is generally safe. However, any medication taken in excess can have serious consequences. If you suspect an overdose, seek medical attention immediately.

  • Symptoms of Zovirax overdose may include:Agitation, kidney failure, lethargy, coma, seizures
  • Acyclovir MedFacts Consumer Leaflet (Wolters Kluwer)
  • Acyclovir Professional Patient Advice (Wolters Kluwer)
  • acyclovir Oral, Intravenous Advanced Consumer (Micromedex) - Includes Dosage Information
  • Acyclovir injection Prescribing Information (FDA)
  • Zovirax Prescribing Information (FDA)
  • Zovirax Consumer Overview

See Also...

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