Medically reviewed on February 17, 2017
What is acyclovir?
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 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
To make sure acyclovir is safe for you, tell your doctor if you have:
kidney disease; or
a weak immune system (caused by disease or by using certain medicine).
Acyclovir is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.
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.
Acyclovir passes into breast milk and may harm a nursing infant. Do not take this medication without telling your doctor if you are breast-feeding a baby.
Do not give an acyclovir buccal tablet to a young child or choking could occur.
How should I take acyclovir?
Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Treatment with acyclovir should be started as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).
Shake the oral suspension (liquid) well just before you measure a dose. Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.
To take the buccal tablet (Sitavig):
Keep the tablet in its blister pack until you are ready to take it. Use a dry finger to remove the tablet.
Do not chew or swallow a buccal tablet. Place the flat side of the tablet against your upper gum, behind your lip and above your canine tooth. Place the tablet on the same side of the mouth as your cold sore.
Close your mouth and gently press on the outside of your lip over the tablet, holding it in place for 30 seconds. Avoid touching or pressing on the tablet once it is in place.
Allow the tablet to dissolve in your mouth throughout the day. You may eat and drink normally while the buccal tablet is in place.
During the first 6 hours of wearing time: If the tablet falls off or does not stick well, you may replace it with a new tablet. If you accidentally swallow the tablet, drink a glass of water and put a new tablet in place.
Tell your doctor if you have any changes in weight. Acyclovir doses are based on weight (especially in children and teenagers), and any changes may affect the dose.
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. Your symptoms may improve before the infection is completely treated. Acyclovir will not treat a viral infection such as the flu or a common cold.
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.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include agitation, seizure (convulsions), or loss of consciousness.
What should I avoid while taking 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 this medicine 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.
Acyclovir side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
easy bruising or bleeding, purple or red pinpoint spots under your skin; 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 may include:
general ill feeling;
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.
See also: Side effects (in more detail)
What other drugs will affect acyclovir?
Acyclovir can harm your kidneys. This effect is increased when you also use certain other medicines, including: antivirals, chemotherapy, injected antibiotics, medicine for bowel disorders, medicine to prevent organ transplant rejection, injectable osteoporosis medication, and some pain or arthritis medicines (including aspirin, Tylenol, Advil, and Aleve).
Other drugs may interact with acyclovir, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Copyright 1996-2018 Cerner Multum, Inc. Version: 5.08.
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- Drug class: purine nucleosides
Other brands: Zovirax