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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 the first outbreak of genital herpes infection. It is also used to treat non-life-threatening herpes infections of the skin and around the mouth (cold sores) in people with a weakened immune system. This medication may decrease the length of time you have pain and help the sores heal faster. Acyclovir is an antiviral drug. It stops the growth of certain viruses.
This medication does not cure herpes or prevent the infection from coming back. Also, it does not prevent the spread of herpes to others.
Other antiviral medications taken by mouth may be more effective in treating these conditions. Discuss your treatment options with your doctor.
Apply this medication to skin only. Avoid getting this medication in your eyes. If this happens, wash right away with plenty of water.
Begin using acyclovir as soon as symptoms of a herpes infection appear. Wash your hands with soap and water before and after using this medication. Clean and dry the affected areas before applying the medication. Use a finger cot or rubber glove when applying acyclovir to prevent spreading the infection to other parts of your body and to other people. Apply enough ointment to cover all sores, usually every 3 hours, 6 times a day, or as directed by your doctor. Continue to use this medication for the full time prescribed.
Tell your doctor if your condition does not improve after 7 days of treatment or if it worsens.
This medication may cause mild, temporary burning or stinging when you apply it. If either of these effects lasts or gets 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 (such as polyethylene glycol), 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.
Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).
Cold sores can spread easily. Avoid close physical contact with others (such as kissing) during an outbreak until the cold sores have completely healed. Try not to touch the cold sore. If you do, wash your hands afterward.
To lower the chance of giving genital herpes to your partner, do not have sexual contact during an outbreak or if you have symptoms. You can spread genital herpes even if you do not have symptoms. Always use an effective barrier method (latex or polyurethane condoms/dental dams) during all sexual activity. Consult your doctor or pharmacist for more details.
Tell your doctor if you are pregnant before using this medication. Discuss the risks and benefits with your doctor.
It is unknown if this medication passes into breast milk. 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.
Wear loose-fitting clothing over your herpes sores to keep from irritating them.
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. Talk to your doctor about identifying and managing these triggers.
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. 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 October 2022.
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