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Generic name: varicella virus (chickenpox) vaccine
Drug class: Viral vaccines

Medically reviewed by  A Ras MD.

What is Varivax used for?

Varivax is a vaccine that is used to prevent chickenpox infection.


VARIVAX [Varicella Virus Vaccine Live] is a preparation of the Oka/Merck strain of live, attenuated varicella virus. The virus was initially obtained from a child with wild-type varicella, then introduced into human embryonic lung cell cultures, adapted to and propagated in embryonic guinea pig cell cultures and finally propagated in human diploid cell cultures (WI-38). Further passage of the virus for varicella vaccine was performed at Merck Research Laboratories (MRL) in human diploid cell cultures (MRC-5) that were free of adventitious agents. This live, attenuated varicella vaccine is a lyophilized preparation containing sucrose, phosphate, glutamate, and processed gelatin as stabilizers.

VARIVAX, when reconstituted as directed, is a sterile preparation for subcutaneous injection. Each approximately 0.5-mL dose contains a minimum of 1350 plaque-forming units (PFU) of Oka/Merck varicella virus when reconstituted and stored at room temperature for a maximum of 30 minutes. Each 0.5-mL dose also contains approximately 25 mg of sucrose, 12.5 mg hydrolyzed gelatin, 3.2 mg of sodium chloride, 0.5 mg of monosodium L-glutamate, 0.45 mg of sodium phosphate dibasic, 0.08 mg of potassium phosphate monobasic, and 0.08 mg of potassium chloride. The product also contains residual components of MRC-5 cells including DNA and protein and trace quantities of sodium phosphate monobasic, EDTA, neomycin and fetal bovine serum. The product contains no preservative.

Mechanism of Action

VARIVAX induces both cell-mediated and humoral immune responses to varicella-zoster virus. The relative contributions of humoral immunity and cell-mediated immunity to protection from varicella are unknown.

Before taking Varivax, tell your doctor:

  • If you are allergic to Varivax; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you have any of these health problems: Active TB (tuberculosis) that is not being treated, certain blood or bone marrow problems like leukemia or lymphoma, a fever, a weak immune system, or a disease that may cause a weak immune system like HIV or AIDS.
  • If you are taking any drugs to suppress your immune system. This may be certain doses of steroids like prednisone. There are many drugs that can suppress your immune system. Ask your doctor or pharmacist if you are not sure.
  • If a family member has had immune system problems.
  • If you are pregnant or plan to get pregnant within the next 3 months. Do not take Varivax if you are pregnant or if you are planning to get pregnant within the next 3 months.
  • If you have had any of these within the past 5 months: Blood transfusion, plasma transfusion, immune globulin drugs like varicella-zoster immune globulin.

This is not a list of all drugs or health problems that interact with this medicine.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take Varivax with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Varivax?

  • Tell all of your health care providers that you take Varivax. This includes your doctors, nurses, pharmacists, and dentists.
  • This medicine may not protect all people who use it. Talk with the doctor.
  • If you will be having a tuberculosis (TB) skin test, you can be tested before, on the same day, or a few weeks after you get this vaccine. This vaccine may affect TB tests. Talk with your doctor if you have questions about when you can have a TB test.
  • Rarely, you can spread the chickenpox virus to others after you get this vaccine. When you are able to, avoid close contact with certain people like newborns, pregnant women who have not had chickenpox, and people with weak immune systems. Do this for up to 6 weeks after getting this vaccine. Talk with your doctor if you cannot avoid close contact with these people.
  • Do not take aspirin or products like aspirin for at least 6 weeks after getting this vaccine. The chance of a very bad illness called Reye’s syndrome may be raised. Reye’s syndrome causes damage to the brain and liver.
  • This medicine may cause harm to the unborn baby if you take it while you are pregnant.
  • If you get pregnant within 3 months after getting Varivax, call your doctor right away.
  • Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

How is Varivax best taken?

Use Varivax as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • It is given as a shot into the fatty part of the skin.

What do I do if I miss a dose?

  • Call your doctor to find out what to do.

What are the side effects of Varivax that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Rash that looks like chickenpox on the body or where the shot was given.
  • Shingles.
  • Rarely, other side effects have happened with Varivax. It is not known if Varivax caused these side effects. Call your doctor right away if you have easy bruising; red or purple, flat spots under the skin; pale skin; trouble walking; severe skin problems, or a skin infection. Call your doctor right away if you have a headache, fever, chills, very upset stomach or throwing up, stiff neck, seizures, you feel sleepy or confused, or if bright lights bother your eyes.

What are some other side effects of Varivax?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Mild fever.
  • Feeling fussy.
  • Pain, redness, or swelling where the shot was given.
  • Irritation where the shot is given.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out Varivax?

  • If you need to store Varivax at home, talk with your doctor, nurse, or pharmacist about how to store it.



  • 10 Single-dose 0.5-mL Vials
    NDC 0006-4827-00
  • Oka/Merck Strain. Human cell tissue culture
    origin containing trace quantities of neomycin.
    Contains no preservatives.
  • Rx only
PRINCIPAL DISPLAY PANEL - 10 Single Dose 0.5 mL Vial Carton


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