Top of the page
Common Brand Name(s): Zovirax
This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.
This medication is used to treat "cold sores/fever blisters" (herpes labialis). It can speed up healing of the sores and decrease symptoms (such as tingling, pain, burning, itching). Acyclovir belongs to a class of medications known as antivirals. It works by stopping the growth of the virus. This medication does not cure herpes, and it does not prevent passing the infection to someone else. It does not prevent a future occurrence.
This section contains uses of this drug that are not listed in the approved US professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.
This drug may also be used for genital herpes. Other medications taken by mouth may work better for genital herpes. Discuss your treatment options with your doctor. This drug does not cure herpes or prevent infection of sexual partners.
Read the Patient Information Leaflet available from your pharmacist. Consult your doctor or pharmacist if you have any questions.
Use this medication at the first sign of infection (such as tingling, burning, redness). Wash your hands with soap and water before and after applying this medication. Clean and dry the affected areas before applying the medication. Apply to the affected area and rub in gently, usually 5 times a day (every 3 to 4 hours) for 4 days for cold sores, or as directed by your doctor. Apply enough cream to cover all affected areas (red/tingling/burning areas, sores).
Apply to skin only. Do not apply this medication in the eyes or nose, inside the mouth, or inside the vagina. If you do get medication in those areas, flush with plenty of water.
Dosage is based on your medical condition, type of infection, and response to treatment. Do not use this drug more often or for longer than prescribed.
Use this medication regularly to get the most benefit from it. This medication works best when the amount of drug absorbed by the skin stays at a constant level. Use this drug at evenly spaced intervals. To help you remember, use it at the same times each day.
To prevent washing off the medication, do not bathe, shower, or swim right after applying it.
If applying to genital herpes sores, use a finger cot or rubber gloves to avoid spreading the infection.
Do not apply other skin products (such as drugs, cosmetics, sun screens, or lip balms) unless told to do so by your doctor. Do not cover the area with plastic or waterproof bandages unless told to do so by your doctor.
Cold sores (herpes) can spread easily. Acyclovir cream does not prevent the spread of herpes. Avoid close physical contact with others (such as kissing) during an outbreak until the cold sores have completely healed. Also, try not to touch the cold sore, and wash your hands if you do touch the cold sore.
If you are using acyclovir for treatment of genital herpes, it is important to follow safe sex practices to reduce the risk of giving herpes to your partner, even if there are no symptoms present. Always use a condom made of latex or polyurethane. When you have symptoms or are experiencing an outbreak, do not have sexual contact with your partner.
Tell your doctor if your condition lasts or gets worse after treatment is finished.
Dry/cracked lips, burning, stinging, or flaky skin may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.
Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Before using acyclovir, tell your doctor or pharmacist if you are allergic to it; or to valacyclovir; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history.
Tell your doctor if you are pregnant before using this medication. Discuss the risks and benefits with your doctor.
Acyclovir may pass into breast milk in small amounts. However, the drug is unlikely to harm a nursing infant. Consult your doctor before breast-feeding. Avoid breastfeeding if you have herpes sores on or near your breast.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
This medicine may be harmful if swallowed. If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Alberta residents can call PADIS (Poison and Drug Information Service) 24 hours a day at 1-800-332-1414. Canada residents can call a provincial poison control center.
Do not share this medication with others. Doing so may spread the infection.
Cold sore outbreaks can be caused by many factors such as stress, hormonal changes (such as pregnancy, menstrual period), injury/surgery on the mouth (such as dental work), tiredness, sunlight, cold weather, or fever/cold/flu.
If you have genital herpes sores, wear loose-fitting clothing to keep from irritating them.
If you miss a dose, use it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Use your next dose at the regular time. Do not double the dose to catch up.
If you have questions about missing a dose or you don't have more medication, contact your healthcare provider or pharmacist.
Store at room temperature. Firmly screw the cap back on the tube of medication after each use. Keep all medications away from children and pets.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised February 2022.
Copyright(c) 2022 First Databank, Inc.
Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.