The Risks of Blood Transfusions

If you are planning to have a blood transfusion, you may be concerned about the risks associated with accepting donated blood. While the risks are minimal, and the supply of blood in the United States is very safe, there are always risks associated with a transfusion.

Extensive screening helps prevent the transmission of infectious diseases; however, there are additional risks that one must consider when considering having a blood transfusion. These risks, some of which are serious, must be weighed against the health concerns that can be caused by a lack of blood or blood cells, such as anemia and hypovolemia.

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Hemolytic Reaction to Blood Transfusion

A hemolytic reaction is a reaction to the administration of donor blood. Steps are taken to prevent severe reactions, starting with lab procedures that help prevent the administration of blood likely to cause a problem. A hemolytic reaction can be life-threatening, and the transfusion will not continue if a reaction occurs.

A hemolytic reaction occurs when the immune system of the patient receiving the blood transfusion destroys the transfused red blood cells. During the administration, additional procedures may be used to reduce the likelihood of a reaction to a transfusion, including giving blood slowly, so that any reaction can be noted prior to a substantial amount of blood being given, and closely monitoring for any signs of difficulty.

The severity of the reaction and the consequences of not giving the blood will determine if the blood will continue to be given or if the transfusion will be stopped. Benadryl, Tylenol or other pain medications, antihistamines, or steroids may be given to stop or reduce a reaction to a transfusion.

In some cases, a patient who is known to have a reaction to blood transfusions is given a transfusion anyway. This is because the risk of the reaction is lower than the risks associated with untreated bleeding.

Signs and Symptoms of an Allergic Reaction

  • Nausea
  • Fever: A sudden fever immediately after the transfusion of blood begins may be a sign of an impending allergic reaction. The patient's temperature should always be taken prior to a transfusion.
  • Anxiety: A patient may have a feeling of impending doom or fear when an allergic reaction is about to happen.
  • Tachycardia: A faster than normal heart rate may happen before a reaction, for this reason, vital signs are typically taken immediately prior to the administration of blood.
  • Hypotension: Blood pressure is lower than normal in some cases of a reaction to blood.
  • Pain: Chest pain and back pain are less common symptoms of a reaction.
  • Dyspnea: Difficulty breathing can appear in severe reactions.
  • Kidney dysfunction: The kidneys can have difficulty filtering blood due to the number of dead blood cells attacked by the immune system.
  • Bloody Urine: Along with kidney dysfunction, the patient's urine can show evidence of blood passed by the kidneys.
  • Flank pain: Kidney dysfunction can be painful and presents as flank pain.
  • Increased Risk of Infection: If your blood donor was ill when they donated or became ill shortly thereafter, your risk of infection is increased. Your risk is higher if your immune system is compromised or if you are extremely ill.
  • Death: Extremely rare, but possible, if a hemolytic reaction is severe enough.

Diseases Spread by Blood Transfusion

The pool of donor blood is screened very carefully for infectious disease and is very safe. However, there is a very small chance of contracting life-threatening diseases from donor blood. There is also a small chance of contracting other illnesses or infections from a blood transfusion.

The National Heart, Lung and Blood Institute estimates that there is approximately a 1 in 2,000,000 chance of contracting Hepatitis C or HIV from a blood transfusion. There is a 1 in 205,000 chance of contracting Hepatitis B.

While it is essential that you are aware of the risks of transfusions, it is also important to keep these odds in perspective. For example, you are four times more likely to be killed by an asteroid than you are to contract HIV or Hepatitis C through a transfusion.

Illnesses That Can Spread by Blood Transfusion

  • Transfusion Related Lung Injury (TRALI): In the hours following a transfusion, difficulty breathing, low blood pressure, fever are present, and a chest X-ray will show pulmonary infiltrates. The patient can have great difficulty getting enough oxygen in severe cases. This diagnosis is uncommon, but many believe it is under-diagnosed and actually happens in one in every 300-5,000 transfusions, and is the third leading cause of transfusion-caused death, depending on the study.
  • Creutzfeldt-Jakob Disease (CJD): A very rare brain disease that is the human equivalent of mad cow disease. The risk of contracting CJD is extremely low, but it is possible if a donor was infected with the disease.
  • Malaria: Typically transmitted by mosquito, the risk of contracting malaria is low in countries where malaria is uncommon. The risk is far greater in areas of the world, such as Africa, where malaria is frequently diagnosed. Malaria causes fever, shaking chills, anemia, muscle pain and headaches.
  • Cytomegalovirus (CMV): A virus that is very common, present in up to 80% of the population. Flu-like symptoms may be present when someone catches CMV, or may not be noticed. People with compromised immune systems may receive blood that has been screened for CMV.
  • Babesiosis and Lyme Disease: Spread by tick bites, both conditions cause chronic fatigue. Babesiosis is similar to malaria, presenting with fever, shaking chills and anemia. Lyme is most common near wooded areas where people hike, Babesiosis is most common near Long Island in the United States.
  • Chagas: A disease spread by parasites, Chagas is most common in Mexico, Central America, and South America. Left untreated, it can cause organ damage, but medication is available through the Centers for Disease Control.
  • Syphilis: A very common illness spread by sexual contact, syphilis causes sores on the genitals and sometimes around the mouth. Syphilis is easily treated but can cause significant health problems if left to progress without medication.
  • Epstein Barr (EBV): One of the herpes viruses, EBV is believed to be present in the bodies of up to 95% of the population. When EBV is contracted by an adolescent, the risk of developing mono, or kissing disease, is an estimated 30-50%.
  • Herpes: While many illnesses are caused by the herpes family of viruses, most people mean genital herpes when they use the term. This virus causes lesions on the genitals and cold sores on the mouth.


The blood supply in the United States is extremely safe, and the likelihood of receiving tainted blood is very low. That does not rule out the possibility of a reaction to donated blood, a sometimes serious issue caused by the body identifying blood as foreign, despite being the same blood type. A reaction is most likely to happen in an individual who has had one in the past, so be sure to notify your healthcare providers if you have experienced a hemolytic reaction during a previous transfusion.

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By Jennifer Whitlock, RN, MSN, FN
Jennifer Whitlock, RN, MSN, FNP-C, is a board-certified family nurse practitioner. She has experience in primary care and hospital medicine.