Antithymocyte Globulin (ATG)

Your child needs to take the medicine called antithymocyte globulin (say: an-tee-THY-moe-site GLOB-yoo-lin). This information sheet explains what antithymocyte globulin does, how to give it, and what side effects or problems your child may have when he or she takes this medicine.

What is antithymocyte globulin?

Antithymocyte globulin is an immunosuppressant. It is used to reduce the body’s immune response. It may be given to children who:

  • are going to have a bone marrow transplant.
  • have graft-versus-host disease.
  • have received an organ transplant such as liver, kidney, heart, or small gut.
  • are experiencing organ rejection.
  • have severe aplastic anemia.

Antithymocyte globulin is prepared from either the blood of horses or rabbits. You may hear antithymocyte globulin called ATG. You may also hear antithymocyte globulin called by its brand names, Atgam® (horse or equine source) and Thymoglobulin® (rabbit source). Antithymocyte globulin comes in an injection form.

Before giving antithymocyte globulin to your child

Tell your doctor if your child has:

  • received either form of ATG (horse or rabbit) in the past.
  • an allergy to ATG.
  • an allergy to rabbit proteins.
  • an allergy to other horse globulin preparations.
  • any other allergies.

Talk with your doctor or pharmacist if your child has any of the following conditions. Precautions may need to be taken with this medicine if your child has:

  • a current infection or recent exposure to infection (for example, chickenpox).
  • persistent, low white blood cell count (leukopenia).
  • persistent, low blood platelet count (thrombocytopenia).

How will antithymocyte globulin be given to your child?

ATG is a liquid given by needle into your child's vein (intravenously or IV) or through a central venous line. It is given very slowly over a period of hours. Your child will get this medicine in the hospital clinic or on a nursing unit.

What are the possible side effects of antithymocyte globulin?

Your child may have some of these side effects while he or she receives antithymocyte globulin. Some side effects are more likely to occur while the drug is being given. These side effects are called infusion reactions. Common infusion reactions with ATG include:

  • fever
  • chills
  • shaking (also called rigors)
  • rash

Because these reactions are common during ATG, your child will probably be given medicine before getting antithymocyte globulin. Acetaminophen (Tylenol®), diphenhydramine (Benadryl®), and corticosteroids (for example, hydrocortisone) may be used while in hospital to try to prevent or ease some of these side effects.

If these side effects occur at home, call your child's doctor right away or take your child to Emergency.

Once your child is out of the hospital, check with your child's doctor if your child continues to have any of these side effects, and they do not go away, or they bother your child:

  • abdominal pain
  • nausea or upset stomach
  • diarrhea (loose, watery stools)
  • headache

Call your child’s doctor during office hours if your child has any of these side effects:

  • weakness, loss of strength
  • muscle and joint pain
  • white patches in the mouth

Most of the following side effects are not common, but they may be a sign of a serious problem. Call your child's doctor right away or take your child to Emergency Department if your child has any of these side effects:

  • fever or chills
  • cough or hoarseness
  • lower back or side pain
  • painful or difficult urination
  • nervousness or confusion
  • irregular heartbeat or fast heartbeat
  • numbness or tingling in hands, feet, or lips
  • shortness of breath or difficulty breathing
  • weakness or heaviness of legs
  • unusual bleeding or bruising
  • black, tarry stools
  • blood in urine or stools
  • pinpoint red spots on skin
  • severe skin rash, itching
  • fainting

What safety measures should you take when your child is using antithymocyte globulin?

The use of ATG combined with other drugs which suppress the immune system may increase the risk of getting severe infections. Your child may be given some antibiotics to lower the risk of getting infections. Other things that you and your child can do to help prevent infections include:

  • avoiding people with infections, such as a cold or the flu
  • avoiding places that are very crowded with large groups of people
  • frequent hand washing to prevent the spread of germs that cause infections
  • you/your child shouldn’t touch your child’s eyes or inside of their nose without washing you/your child’s hands first

Your child should not receive any immunizations (vaccines) without your child's doctor's approval. Your child or anyone else in your household should not get oral polio vaccine while your child is being treated with ATG. Tell your child's doctor if anyone in your household has recently received oral polio vaccine. Your child should avoid contact with anyone who has recently received this vaccine. Other live vaccines that your child should not get include measles, mumps, and rubella (MMR) and chickenpox vaccine.

ATG can lower the number of platelets in the blood, which increases your child’s risk of bleeding. You can take the following precautions:

  • Be careful not to cut your child when using a razor, scissors, or clippers to cut his or her nails or hair.
  • Your child should be careful when shaving or waxing.
  • Your child should avoid contact sports where bruising or injury could occur.
  • Your child should not receive a permanent tattoo or any kind of body piercing.
  • Before your child has surgery, including dental surgery, inform the doctor or dentist that your child is receiving ATG.
  • Be careful when brushing or flossing your child's teeth. Your child’s doctor, nurse, or dentist can tell you about other ways to clean your child's mouth and teeth.

Your child may still have side effects 1 or 2 weeks after he or she has finished getting antithymocyte globulin. Call your child's doctor or nurse right away if your child has any of the following signs:

  • fever
  • tiredness
  • sore joints or muscles
  • rash
  • throwing up
  • swollen glands
  • changes in vision

The use of ATG with other immunosuppresants may increase the risk of getting certain types of cancer, such as lymphoma. Check with your doctor right away if any of the following signs occur even after ATG treatment has stopped:

  • yellow eyes or skin
  • black tarry stools
  • blood in urine or stools
  • unusual bleeding or bruising
  • swelling in the neck, armpit, or groin, or unexplained swelling in an arm or leg
  • fever and chills
  • unexplained weight loss
  • night sweats
  • lack of energy

There is a chance that ATG may cause birth defects if it is taken at the time of conception or if it is taken during pregnancy. If your child is sexually active it is recommended that she use some kind of birth control while receiving ATG. Tell the doctor right away if your child may be pregnant.

Check with your child’s doctor or pharmacist before giving your child any other medicines (prescription, non-prescription, herbal, or natural products).

What other important information should you know about antithymocyte globulin?

Keep a list of all medications your child is on and show the list to the doctor or pharmacist.

Do not share your child’s medicine with others and do not give anyone else’s medicine to your child.

Do not keep any medicines that are out of date. Check with your pharmacist about the best way to throw away outdated or leftover medicines.

Keep medicine out of your child’s sight and reach and locked up in a safe place. If your child takes too much medicine, call the Ontario Poison Centre at one of these numbers. These calls are free.

  • Call 416-813-5900 if you live in Toronto.
  • Call 1-800-268-9017 if you live somewhere else in Ontario.
  • If you live outside of Ontario, call your local poison information centre.

Disclaimer: The information in this Family Med-aid is accurate at the time of printing. It provides a summary of information about antithymocyte globulin and does not contain all possible information about this medicine. Not all side effects are listed. If you have any questions or want more information about antithymocyte globulin, speak to your healthcare provider. ​

Amelia Rodrigues, BScPhm, ACPR, RPh​