Skip to main content


Therapy for preventing blood clots


Central venous lines and certain chemotherapy drugs can sometimes cause blood clots to form more quickly. Blood clots in veins and arteries can cause the blood supply to be slowed or stopped to a portion of the body. When the blood flow is slowed or stopped by a clot, the area of the body not getting the blood can swell, become discolored, or have pain. In some cases, the clot can begin to move through the vein and become lodged in an area like the lung, where it can cause serious breathing problems. For this reason, some cancer patients receive medicine to thin the blood and keep it from clotting too much. These medicines are called anticoagulants (AN ty koh AG yoo lents). They include such drugs as heparin, enoxaparin (Lovenox®) and warfarin (Coumadin®).

A few US hospitals have reported serious errors in giving these blood thinners. The errors led to the injury of several infants, and in some cases the babies died. The heparin overdose given was caused by two very different doses of heparin being stocked in vials (bottles) that looked alike.

St. Jude has had safety systems in place for many years to help prevent blood thinner errors. Still, the staff has learned something from each medicine error at other hospitals and from a review of the research. The staff continues to improve St. Jude systems for using medicines to decrease the risk of similar errors happening here. Despite these precautions, heparin and other blood thinners are still high-risk medicines. The staff needs you to be aware of the risks and know what you can do to help keep your child safe.

General guidelines for blood thinners

  • If your child is taking a blood thinner, the staff will take blood samples often to check how quickly the blood is clotting. To get the best test results, the blood samples must be taken from a vein using a needle or from a central venous line that has never received heparin. We know your child does not like needle sticks, but this is the only way to get correct results that will help ensure your child’s health and safety while taking this drug.
  • Your child should not take a blood thinner on the day of a procedure or surgery. Your child will stop taking this medicine 12 to 24 hours before and after depending on the type of procedure or surgery. Talk to your child’s doctor, nurse or pharmacist if you have questions about when to stop giving this medicine.
  • Some medicines that thin the blood are given to prevent blood clots throughout the body. Other blood thinning medicines are given to prevent clots from forming in central venous lines. If your child has a central venous line, you or the staff might be flushing the line with a blood thinner at certain times each day. If you are involved in flushing the line, follow guidelines carefully.

Blood thinners can be hazardous drugs. If your child is taking one of these medicines, please read the Patient Medication information for the drug, so you can learn the safety precautions and possible side effects. Your child’s nurse, doctor, or pharmacist can give you the Patient Medication sheet for the blood thinner being used for your child. See Patient Medication information including “Heparin Lock Flush for Children and Young Adults,” “Heparin Lock Flush for Infants,” “Warfarin,” and “Enoxaparin.”


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).