Varicella-Zoster Immune Globulin (Intramuscular)

Varicella Zoster Immune Globulin or VZV is a medication used mostly for immunosuppressed patients who have been predisposed to the varicella-zoster virus as it protects against its dissemination. Listed below is more information on this immune system medication.


Varicella Zoster Immune Globulin is a drug in the class of coinfections and opportunistic infections with its brand name being VARIZIG. There are various labels for this drug that are FDA approved. It was first administered in 1969 to patients convalescing from herpes zoster and showed prevention attributes of clinical varicella in vulnerable normal children if given within 72 hours after exposure.

The drug is administered for protection after exposure to varicella virus in high-risk individuals. Such individuals include:

  • Premature infants
  • Infants younger than one year
  • Children and adults who have compromised immunity
  • Newborns born to mothers with varicella
  • Pregnant women


  • Chickenpox or varicella zoster virus

Type of Medicine

  • Vaccine

Side Effects

The side effects are few and minor. The most common ones are outlined below:

  • The person who receives the injection experiences local discomfort at the site of the injection. There is also pain, redness and swelling at the injection site in at least 1% of patients.
  • Rash (including terms pruritus, rash erythematous, rash, urticaria and rash vesicular)
  • Gastrointestinal symptoms are also seen quite infrequently, in less than 0.2% of recipients of the drug.
  • Respiratory issues also occur in less than 0.2% of patients.
  • Headaches and malaise are also seen in approximately 0.2% of recipients.

Other less frequent symptoms include the following;

  • Nausea which may or may not be accompanied by vomiting
  • Chills
  • Fever
  • Joint pain
  • Hives
  • Itching which may accompany a rash
  • Angioneurotic edema and anaphylactic shock are severe side effects that are rare and occur in less than 0.1% of patients.


This medicine is for intramuscular use only.

The following are the various doses of VARIZIG to be administered depending on body weight:

  1. For infants, with weight less than or equal to 2kg or 4.4lbs. Administer 62.5 IU, 0.5 vials or 0.6ml volume.
  2. Body weight of 2.1 to 10kgs, or 4.5 to 22lbs, administer 125IU, or 1 vial. Volume of 1.2ml
  3. Body weight of 10.1 to 20kgs, or 22.1 to 44lbs, administer 250IU, which is 2 vials. Volume is 2.4ml.
  4. Body weight of 20.1 to 30kgs, or 44.1 to 66lbs, administer 375IU, which is 3 vials or 3.6ml.
  5. Body weight of 30.1 to 40kgs, or 66.1 to 88kgs, administer 500IU, which is 4 vials or 4.8ml.
  6. From 40.1kgs and over, 88.5lbs administer 625IU, or 5 vials or 6ml.

A second full dose of VARIZIG should be given to patients who are at high risk and have had further exposure to the virus after three weeks of receiving the first dosage.

Do consider the following while administering Varicella Zoster Immune Globulin or VARIZIG.

  • A vial of the drug contains a potency of 125IU at the lowest in every 1.2ml.
  • Before you use this drug, bring it to room temperature.
  • If the solution of VARIZIG is cloudy or contains particulate matter, do not use. Inspect it before administering to anyone to ensure it is a clear solution.
  • VARIZIG cannot be stored after it is opened. It is for a single use only as it does not contain any preservatives. Anything that left in the vial should be discarded.


This medicine should be injected into the deltoid muscle or in the anterolateral aspects of the thigh, upper section. The gluteal region should not be used as an injection site because of the risk of sciatic nerve injury.

If the medicine must be injected in the gluteal region, use only the outer upper quadrant. It should never be administered intravenously.

A single dose can be administered at two or more injection sites. The dosage can be divided into two or more portions to be administered at different sites. Do not inject more than 3ml per site.

As is common in medical practice, the same disposable sterile syringe and needle should not be used on different patients. This will prevent transmitting the disease or any other between patients.


Any drugs that a person may be taking including herbal preparations, supplements, vitamins, prescription and over the counter drugs may interact with Varicella Zoster Immune Globulin. Inform a medical practitioner of other drugs that are in use so that they can determine what interactions could occur.

Varicella Zoster Immune Globulin mainly interacts with other live attenuated virus vaccines and impairs their efficacy. Such vaccines may need to be administered again after use of this chickenpox vaccine.

There are 21 drugs, 54 generic and brand names that have a moderate interaction with VARIZIG. Moderate interaction implies that the two drugs should be used together only in exceptional circumstances. The interaction between such drugs is clinically significant.

Here is a list of these drugs.

  • ACAM2000 (smallpox vaccine)
  • Attenuvax (Measles virus vaccine)
  • BCG
  • Biavax II (Mumps and rubella virus vaccine)
  • Cerebyx (fosphenytoin)
  • Di-phen (phenytoin)
  • Dryvax (smallpox vaccine)
  • Dilantin (Phenytoin)
  • Ethotoin
  • FluMist (Influenza virus vaccine, live, trivalent)
  • FluMist Quadrivalent (Influenza virus vaccine, live, trivalent)
  • Fosphenytoin
  • Influenza virus vaccine, h1n1, live
  • Influenza virus vaccine, live, trivalent)
  • M -M-R II (Measles, mumps and rubella virus vaccine.)
  • M-R-Vax II (Measles and rubella virus vaccine)
  • Measles virus vaccine
  • Measles, mumps and rubella virus vaccine
  • Measles, mumps, rubella, and varicella virus vaccine
  • Measles and rubella virus vaccine
  • Mephenytoin
  • Meruvax II (Rubella virus vaccine)
  • Mesantoin (Mephenytoin)
  • Mumps virus vaccine
  • Mumps and rubella virus vaccine
  • Mumpsvax (Mumps Virus Vaccine)
  • Peganone (Ethotoin)
  • Orimune (Polio Virus Vaccine, trivalent)
  • Phenytek (Phenytoin)
  • Phenytoin
  • Phenytoin Sodium (Phenytoin)
  • Phenytoin Sodium, Extended Release (Phenytoin)
  • Phenytoin Sodium, Prompt (phenytoin)
  • Poliovirus vaccine, live, trivalent
  • ProQuad (Measles, Mumps, Rubella, Varicella vaccine)
  • Rotarix (Rotavirus vaccine)
  • Rotavirus vaccine
  • Rubella virus vaccine
  • RotaShield (rotavirus vaccine)
  • RotaTeq (Rotavirus Vaccine)
  • Smallpox vaccine
  • Stamaril (Yellow fever vaccine)
  • TheraCys (BCG)
  • Tice BCG (BCG)
  • Tice BCG vaccine (BCG)
  • Typhoid vaccine, live
  • Varicella virus vaccine
  • Varivax (varicella virus vaccine)
  • Vivotiff Berna (typhoid vaccine, live)
  • ¬†Vivotiff Berna vaccine (typhoid vaccine, live)
  • Yellow fever vaccine
  • YF -Vax (Yellow Fever Vaccine)
  • Zostavax (Zoster Vaccine Live)
  • Zoster vaccine live


  1. Coagulation Disorders

For patients with coagulation disorders that do contraindicate intramuscular injections, this drug should be administered if the benefits outweigh the risks.

  1. Thrombotic Events

Patients who are at risk of thrombotic events after or during use of Varicella Zoster Immune Globulin have certain conditions. These include mainly those with any of the following issues:

  • Multiple cardiovascular risk factors
  • Advanced in age
  • Coagulation disorders
  • A history of atherosclerosis
  • Impaired cardiac output
  • Prolonged periods of immobilization such as someone who is bedridden
  • Suspected or known hyperviscosity
  1. Transmissible Infectious Causes

Varicella Zoster Immune Globulin is made from human plasma and may carry the risk of transmitting other infectious agents. The human plasma donors are thoroughly screened for infectious diseases and others to ensure they are healthy. During manufacture of the drug, measures are put in place to deactivate and remove any viruses that may still be present even after initial screening. But despite all these measures, the vaccine could still transmit diseases.

  1. Hypersensitivity

Severe reactions of hypersensitivity may occur after use of VARIZIG. Patients who are expressly at more significant risks of severe hypersensitivity and anaphylactic reactions are those with known antibodies to IgA.

VARIZIG should be administered only in environments where there are medical personnel, medication and emergency equipment to handle anaphylaxis, shock, and hypersensitivity. In case of reactions to hypersensitivity, treatment should be discontinued and appropriate medication administered.


VARIZIG should be stored in the original vial at temperatures of 2 to 8 degrees centigrade. The drug should not be frozen. The vial should not be removed from the outer carton to keep the stored drug protected from light.

The drug can be kept in its original container at ambient temperatures of 25 degrees centigrade for short periods of up to one week.


VARIZIG provides the human body with what it needs to protect itself from the chicken pox virus. This is referred to as passive protection. It works successfully in most of the cases where it is administered.

Chickenpox, also referred to as varicella, easily spreads from one person to the other. In itself, varicella is not such a severe disease, but it can result in severe problems. These include inflammation of the brain, pneumonia, and a sporadic illness referred to as Reye's syndrome.

Because of these potential complications, it's necessary to be protected from chicken pox, whenever there has been exposure to the virus that causes it. VARIZIG must be prescribed by a medical practitioner.

VARIZIG is very safe to use. The doctor prescribing the drug should be informed of any medications in use to be able to determine the safety of using VARIZIG. Also, notify the doctor of any diseases the patient may have. Proper supervision of a medical practitioner is what will result in a successful outcome using this drug.

Last Reviewed:
December 24, 2017
Last Updated:
April 05, 2018
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