Acyclovir is an antiviral drug. It slows the growth and spread of the herpes virus in the body. Acyclovir will not cure herpes, but it can lessen the symptoms of the infection.

Acyclovir is used to treat infections caused by herpes viruses, such as genital herpes, cold sores, shingles, and chicken pox.

Sitavig buccal tabets are for use in treating only cold sores on the lips. Sitavig will not treat genital herpes.

Acyclovir may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not take acyclovir if you are allergic to acyclovir or valacyclovir (Valtrex). You should not take Sitavig buccal tablets if you are allergic to milk proteins.

Tell your doctor if you have ever had:

• kidney disease; or

• a weak immune system (caused by disease or by using certain medicine).

Tell your doctor if you are pregnant or breastfeeding.

Herpes can be passed to your baby during childbirth if you have a genital lesion when your baby is born. If you have genital herpes, it is very important to prevent herpes lesions during pregnancy. Take your medicine as directed to best control your infection.

It may not be safe to breastfeed while using this medicine. Ask your doctor about any risk.

Acyclovir should not be given to a child younger than 2 years old.

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:

1. Find the area on the upper gum above your left and right incisor teeth (the teeth just to the left and right of your two front teeth).
2. With dry hands, remove one delayed-release tablet from the container.
3. Gently apply the tablet to the upper gum area as high as it will go on your gum above one of your incisor teeth on the side of your mouth with the cold sore. Do not apply it to the inside of the lip or cheek.
4. Hold the tablet in place for 30 seconds.
5. If the tablet does not stick to your gum or if it sticks to your cheek or the inside of your lip, reposition it to stick to your gum. Leave the tablet in place until it dissolves.
6. Do not interfere with the placement of the tablet. Check to see if the tablet is still in place after eating, drinking, or rinsing your mouth.

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:

• Do not chew gum, touch, or press the buccal tablet after it has been applied.
• Do not wear upper dentures.
• Do not brush your teeth until it dissolves. If your teeth need to be cleaned while the tablet is in place, rinse the mouth gently.

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.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Start taking acyclovir as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters). Start taking Sitavig within 1 hour after you first notice sold core symptoms, before the cold sore appears.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.

Do not crush, chew, suck on, or swallow a buccal tablet. Place the flat side of the tablet against your upper gum, on the same side of the mouth as your cold sore. Allow the tablet to dissolve in your mouth throughout the day. You may eat and drink normally while the buccal tablet is in place.

Do not give an acyclovir buccal tablet to a young child or choking could occur.

Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Acyclovir doses are based on weight (especially in children and teenagers). Your dose needs may change if you gain or lose weight.

Drink plenty of water while you are taking acyclovir to keep your kidneys working properly.

Use this medicine for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses may increase the risk of your virus becoming resistant to medication.

Lesions caused by herpes viruses should be kept as clean and dry as possible. Wearing loose clothing may help to prevent irritation of the lesions.

Store at room temperature away from moisture and heat.

You should not take acyclovir if you are allergic to acyclovir or valacyclovir (Valtrex). You should not take Sitavig buccal tablets if you are allergic to milk proteins.

Tell your doctor if you have ever had:

• kidney disease; or

• a weak immune system (caused by disease or by using certain medicine).

Tell your doctor if you are pregnant or breastfeeding.

Herpes can be passed to your baby during childbirth if you have a genital lesion when your baby is born. If you have genital herpes, it is very important to prevent herpes lesions during pregnancy. Take your medicine as directed to best control your infection.

It may not be safe to breastfeed while using this medicine. Ask your doctor about any risk.

Acyclovir should not be given to a child younger than 2 years old.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

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. http://www.upandaway.org

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 (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

Drink plenty of fluids while you are taking or using acyclovir.

Avoid brushing your teeth, chewing gum, or wearing an upper denture while you have a buccal tablet in your mouth. You may rinse your mouth gently. Drink plenty of liquids to prevent dry mouth.

Herpes infections are contagious and you can infect other people, even while you are being treated with acyclovir. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent passing the infection to others.

Taking acyclovir will not prevent you from passing genital herpes to your sexual partner. Avoid sexual intercourse while you have active lesions or the first symptoms of an outbreak. Genital herpes may still be contagious through "viral shedding" from your skin, even if you have no symptoms.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Acyclovir may cause serious side effects. Call your doctor at once if you have:

• easy bruising or bleeding, purple or red pinpoint spots under your skin;

• changes in behavior;

• confusion, hallucinations; or

• signs of a kidney problem--little or no urinating; painful or difficult urination; swelling in your feet or ankles; feeling tired or short of breath.

Common side effects of acyclovir may include:

• mild skin pain;

• rash, itching;

• nausea, vomiting, diarrhea;

• headache; or

• mouth pain while using an acyclovir buccal tablet.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Acyclovir can harm your kidneys, especially if you also use certain medicines for infections, cancer, osteoporosis, organ transplant rejection, bowel disorders, high blood pressure, or pain or arthritis (including Advil, Motrin, and Aleve).

Other drugs may affect acyclovir, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

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.

You should start to feel better after using acyclovir for a few days.

Tell your doctor if your symptoms don’t improve or you feel worse while taking this medicine.

Your dosage will depend on your medical condition, the brand of acyclovir you use, the formulation you use, and other factors.

Start taking this medicine at the first sign of symptoms and follow your doctor’s dosing instructions carefully.

Acyclovir is sometimes used to treat other medical conditions, including:

• Eczema herpeticum (a skin infection caused by the herpes virus)
• Oral hairy leukoplakia (a condition that causes hairy white or gray-colored patches on the tongue or inside the mouth)
• Human immunodeficiency virus (HIV)