Acyclovir is used to decrease pain and speed the healing of sores or blisters in people who have varicella (chickenpox), herpes zoster (shingles; a rash that can occur in people who have had chickenpox in the past), and first-time or repeat outbreaks of genital herpes (a herpes virus infection that causes sores to form around the genitals and rectum from time to time). Acyclovir is also sometimes used to prevent outbreaks of genital herpes in people who are infected with the virus. Acyclovir is in a class of antiviral medications called synthetic nucleoside analogues. It works by stopping the spread of the herpes virus in the body. Acyclovir will not cure genital herpes and may not stop the spread of genital herpes to other people.
Acyclovir comes as a tablet, a capsule, and a suspension (liquid) to take by mouth. It also comes as a delayed-release buccal tablet to apply to the upper gum of the mouth. The tablets, capsules, and suspension are usually taken with or without food two to five times a day for 5 to 10 days, starting as soon as possible after your symptoms begin. When acyclovir is used to prevent outbreaks of genital herpes, it is usually taken two to five times a day for up to 12 months. The delayed-release buccal tablet is usually applied with a dry finger as a one-time dose within 1 hour after itching, redness, burning or tingling cold sore symptoms begin but before the cold sore appears. Take or use acyclovir at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take or use acyclovir exactly as directed. Do not take or use more or less of it or take it more often or for a longer time than prescribed by your doctor.
Do not chew, crush, suck, or swallow the delayed-release buccal tablets. Drink plenty of liquids, if you have a dry mouth while using the delayed-release buccal tablets.
To use buccal acyclovir, follow these steps:
If the delayed-release buccal tablet comes off within the first 6 hours of application, reapply the same tablet. If it still will not stick, then apply a new tablet. If you accidentally swallow the tablet within the first 6 hours of application, drink a glass of water and place a new tablet on your gum. If the tablet falls off or is swallowed 6 or more hours after application, do not apply a new tablet until your next regular time.
Avoid the following while you are using acyclovir buccal delayed-release tablet:
Shake the suspension well before each use to mix the medication evenly.
Your symptoms should improve during your treatment with acyclovir. Call your doctor if your symptoms do not improve or if they get worse.
Take or use acyclovir until you finish the prescription, even if you feel better. If you stop taking acyclovir too soon or skip doses, your infection may not be completely treated or may become more difficult to treat. The delayed-release buccal tablet is applied as a one-time dose.
Acyclovir is also sometimes used to treat eczema herpeticum (a skin infection caused by the herpes virus) to treat and prevent herpes infections of the skin, eyes, nose, and mouth in patients with human immunodeficiency virus (HIV), and to treat oral hairy leukoplakia (condition that causes hairy white or gray-colored patches on the tongue or inside of the cheek).
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.
Before taking acyclovir,
Drink plenty of fluids while you are taking or using acyclovir.
Take the missed dose as soon as you remember it and take any remaining doses for that day at evenly spaced intervals. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Acyclovir may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:
Acyclovir may cause other side effects. Call your doctor if you have any unusual problems while you are taking or using this medication.
If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( Web Site ) or by phone (1-800-332-1088).
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).
It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. Web Site
Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( Web Site) for more information if you do not have access to a take-back program.
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at Web Site. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.
Symptoms of overdose may include the following:
Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your response to acyclovir.
Do not let anyone else take or use your medication. Ask your pharmacist any questions you have about refilling your prescription.
It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.
AHFS® Consumer Medication Information. © Copyright, The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.
Selected Revisions: November 15, 2019.