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Generic name: acyclovir (oral) [ a-SYE-klo-veer ]
Drug class: Purine nucleosides

Medically reviewed by Philip Thornton, DipPharm. Last updated on Aug 22, 2023.

What is Sitavig?

Sitavig (acyclovir) is a prescription medicine used to treat recurrent cold sores (herpes labialis) in adults with normal immune systems. Acyclovir slows the growth and spread of the herpes virus in the body. It does not cure herpes, but it can lessen the symptoms of the infection.

Sitavig is buccal tablet used as a single dose placed under the upper lip in gum area above the incisor tooth (canine fossa).

Sitavig belongs to a class of antiviral medications called synthetic nucleoside analogues. Acyclovir works by stopping the spread of the herpes virus in the body.

Sitavig is for use in treating only cold sores on the lips and will not cure genital herpes and may not stop the spread of genital herpes to other people.

Sitavig side effects

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

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

Common Sitavig side effects may include:

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.

Before taking this medicine

To make sure Sitavig is safe for you, tell your doctor if you have ever had:

Tell your doctor if you are pregnant or breastfeeding.

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

How should I take Sitavig?

Take Sitavig as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.

Start taking Sitavig as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters). Apply the buccal tablet 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 a Sitavig buccal tablet to a young child or choking could occur.

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

Store at room temperature away from moisture and heat.

Instructions for Use

Sitavig should be taken within one hour after you have the first symptom of a cold sore, such as itching, redness, burning, or tingling, and before a cold sore appears.

How to use Sitavig:

Step 1:
Before you apply Sitavig, find the area on your upper gum, just above either the left or the right incisor. The incisor tooth is the tooth just to the right or left of your two front teeth. This is where you should apply the buccal tablet.

Step 2:
Peel back the cover of the blister pack. Take one buccal tablet out of the blister pack. When removed from the blister pack, Sitavig must be used right away. The buccal tablet is round on one side and flat on the other side.

Step 3:
Place the flat side of the buccal tablet on your dry fingertip. Apply the round side to your upper gum. The flat side will be facing the inside of your lip.

Step 4:
Hold buccal tablet in place by applying a slight pressure with your finger on the outside of your upper lip, over the area where Sitavig is placed, for 30 seconds. This will help it stick to your gum.

Step 5:
Leave the buccal tablet in place until it dissolves.

Dosing Information

Usual Adult Dose for Herpes Simplex Labialis:

Immunocompetent host:
Apply 50 mg (1 buccal tablet) as a single-dose to the upper gum region (canine fossa)

-Tablet should be applied within 1 hour after the onset of prodromal symptoms and before the appearance of any signs of herpes labialis lesions.
-Tablet should be applied on the same side of the mouth as the herpes labialis symptoms.
-Use of buccal tablets has not been studied in immunocompromised subjects.

Use: For the treatment of recurrent herpes simplex labialis (cold sores).

What happens if I miss a dose?

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.

What happens if I overdose?

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

What should I avoid while taking Sitavig?

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 Sitavig. 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.


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

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.

What other drugs will affect Sitavig?

Sitavig 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 interact with 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.


Active ingredient: acyclovir.
Inactive ingredients: hypromellose, milk protein concentrate, sodium lauryl sulfate, magnesium stearate,microcrystalline cellulose, povidone, colloidal silicon dioxide.


Farméa, 10 rue Bouché Thomas, ZAC d’orgemont, 49 000 Angers, France

Frequently asked questions

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Sitavig only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.