Most people experience no complications during a blood transfusion, but some have adverse reactions during or after treatment. Examples include a fever, chills, itching, or breathing difficulty.

According to the American Red Cross, people do not typically experience complications after having a blood transfusion, but they can happen occasionally and can range from mild to severe.

The Centers for Disease Control and Prevention (CDC) state that the most common adverse reactions are allergic and febrile (fever) transfusion reactions.

In this article, we discuss the potential reactions a person may experience due to a blood transfusion.

A blood bag pictured before a blood transfusion, which may cause reactions.Share on Pinterest
Symptoms of a blood transfusion reaction, while uncommon, include fever, chills, and respiratory distress.

According to a 2020 article, the most common signs that indicate a person is experiencing an adverse reaction include:

However, these symptoms can resolve with little or no treatment.

Signs that indicate a more severe reaction include:

Examples of acute transfusion reactions include the following:

Simple allergic reaction

Even when a person receives the correct blood type, allergic reactions can occur.

According to a 2013 article in the British Journal of Haematology, reactions occur due to:

  • the donor blood containing specific plasma proteins that the recipient’s blood sees as allergens
  • the donor blood containing food allergens, such as peanut or gluten
  • antibodies in donor blood react with antibodies in the recipient’s blood


Symptoms are typically mild and include:

  • rash
  • itching
  • hives


Treatments for a mild allergic reaction include:

  • stopping the transfusion
  • taking an antihistamine to help treat an allergic reaction

Anaphylactic transfusion reaction

Anaphylactic reactions occur in those with immunoglobulin A (IgA) deficiencies and have IgA antibodies in their plasma.

The recipient’s anti-IgA antibodies can react with the IgA antibodies in the donor blood.


Symptoms typically include:

  • flushed skin
  • itching
  • hives
  • swelling
  • difficulty breathing
  • wheezing
  • blue lips
  • vomiting
  • diarrhea
  • low blood pressure


If a person is experiencing any of the above symptoms, a nurse or doctor will stop the transfusion. After this, they will address the specific symptoms, which can include:

  • intravenous (IV) epinephrine
  • IV steroids
  • antihistamines
  • bronchodilators

Febrile non-hemolytic transfusion reaction

According to the CDC, a febrile non-hemolytic transfusion reaction (FNHTR) is the most common reaction. It involves an unexplained rise in temperature during or 4 hours after the transfusion.

The fever is part of the person’s white blood cells response to the new blood.


Symptoms will depend on the severity and may include:

If other symptoms are present, the person should contact their doctor.


If FNHTR occurs during the transfusion, the healthcare professional will stop the procedure.

Treatment depends on the symptoms. However, according to the CDC, most reactions are typically mild and respond quickly to treatment.

  • investigating all cases of fever as it may indicate a more severe cause
  • taking the recommended dose of aspirin or acetaminophen

Acute hemolytic transfusion reaction

According to the CDC, this type of reaction occurs during, immediately afterward, or within 24 hours of the transfusion. This type of reaction occurs if a person has received the wrong blood type.

A 2019 article states that an acute hemolytic transfusion reaction causes the body to start destroying the donated red blood cells.


Symptoms can include:

  • chills
  • low blood pressure
  • renal failure
  • back pain

Less common symptoms include:

  • flank pain
  • fever
  • red or brown urine


If a person develops an acute hemolytic transfusion reaction, the doctor or nurse will stop the transfusion.

Treatment depends on the severity of the reaction and may include:

  • IV fluids
  • dialysis
  • management of bleeding
  • supportive care

Septic transfusion reactions

According to a 2012 article, septic transfusion reactions typically occur due to bacterial contamination of the donor blood components, most commonly from the platelet products.

The bacteria in platelets that can cause a septic transfusion reaction include Staphylococcus aureus and Staphylococcus epidermidis.


Symptoms can include:

  • a fever
  • chills
  • low blood pressure.


Septic transfer reactions require immediate attention. Management of the condition involves

  • fluid management
  • respiratory support
  • antibiotic therapy.

Transfusion-related acute lung injury (TRALI)

This blood transfusion reaction develops very quickly. It happens when antibodies in the donor blood, such as human leukocyte antibodies, react with the recipient’s leukocytes, or white blood cells. This results in pulmonary edema, or excess fluid in the lungs.

According to the American Red Cross, no specific test exists to identify which blood products will cause TRALI.


Symptoms of TRALI include:

  • severe shortness of breath
  • fever
  • low blood pressure


Treatment depends on the severity of the symptoms:

  • For mild cases, a person will need oxygen therapy.
  • For more severe cases, a person may require artificial ventilation.

According to a 2012 article, most cases typically resolve within 48–72 hours. However, TRALI can be fatal and has a mortality rate of between 5–25%.

Transfusion-associate circulatory overload (TACO)

TACO occurs if a person’s circulatory system is unable to process the amount of blood or the speed at which they are receiving it. Doctors call this volume overload, and people who have heart or kidney conditions may develop it.

In TACO, the circulatory system becomes overwhelmed, resulting in pulmonary edema where the lungs fill up with excess fluid.


Symptoms of TACO usually occur within a few hours of or during the transfusion and include:


If symptoms occur during the transfusion, the doctor or healthcare professional will stop the procedure immediately.

According to LabMedicine, treatment for TACO depends on the severity.

  • placing the person in an upright position is often sufficient to treat mild TACO
  • treating a person with diuretics to remove excess fluid may help resolve more advanced TACO
  • intubating to improve respiration is sometimes necessary in severe cases

Examples of delayed transfusion reactions include the following:

Delayed hemolytic or delayed serologic transfusion reaction

A delayed hemolytic or delayed serologic transfusion reaction occurs when an antibody that the recipient already has reforms and reacts to red cell antigens. Reactions can occur between 1 day and 4 weeks after the transfusion.

A person can acquire these antibodies through previous pregnancies or transfusions. These particular antibodies decrease over time to undetectable levels. Those with the antibodies have a higher chance of developing these transfusion reactions.


Symptoms typically include:

  • fever
  • jaundice
  • abdominal pain
  • dark urine
  • high blood pressure
  • labored breathing


According to LabMedicine, these transfusion reactions tend to be mild and do not require treatment. If the reaction is significant, hydration is important.

Transfusion-associated graft versus host disease (TAGVHD)

According to the CDC, TAGVHD occurs when T-lymphocytes, a type of white blood cell, from the donor blood rapidly increase in number in the recipient. They then attack the recipient’s cells.

However, it is a very rare occurrence, and it has become less prevalent since the introduction of the irradiation of blood products. Blood irradiation involves exposing the blood components to ultraviolet light.


According to the CDC, symptoms include:

  • rash
  • nausea
  • vomiting
  • diarrhea
  • abdominal pain
  • fever
  • bone marrow failure


Doctors find TAGVHD challenging to treat, and as a result, mortality rates are between 90–100%.

  • Prevention is the best form of treatment. Using irradiation can help prevent the chance of a person developing TAGVHD.

Posttransfusion purpura (PTP)

The CDC state that PTP is rare. It occurs when the recipient develops antibodies against the platelets. This results in the destruction of platelets and a decline in platelet numbers.


According to a 2019 article, symptoms of PTP can include:

  • bleeding of the gastrointestinal tract and urinary tract
  • fever and chills


Treatment may include:

  • supportive care
  • IV immunoglobins and steroids

According to the authors of Transfusion Medicine for Pathologists: A Comprehensive Review for Board Preparation, Certification, and Clinical Practice, it is important to note that transfusion reactions are rarely fatal. The incidence of fatal reactions can vary from 1 in 0.6 million to 2.3 million.

A summary of the blood transfusion reactions are as follows:

Acute reactions

Simple allergic1–3% of all transfusionsRash, itching, and hivesDuring or within 4 hoursMildAntihistamines
Anaphylactic1 in 20,000–30,000 transfusionsFlushed skin, itching, hives, swelling, difficulty breathing, wheezing, blue lips, vomiting, diarrhea, low blood pressureSeconds to minutes at the beginning of the transfusionPotentially fatalIV epinephrine, antihistamines, IV steroids, bronchodilators
Febrile nonhemolytic transfusion reaction1–3% per unit of blood transfusedRise in temperature by at least 1% and chillsWithin 4 hoursMildAntipyretics
Acute hemolytic transfusion reaction2–8% per 10,000 units f blood transfusedFever, flank pain, low blood pressure, renal failure, and difficulty breathingDuring, immediately afterward, or within 24 hoursPotentially fatalSupportive therapy using IV fluids, dialysis if necessary, and management of bleeding
Septic transfusion reaction1 in 3000–5000 units of plateletsFever, chills, and hypotensionWithin 4 hoursPotentially fatalAntibiotic therapy, fluid management, respiratory support
TRALI0.4% per 100,000 units of plasmaDifficulty breathing, fever, and high blood pressureDuring or within 6 hoursPotentially fatalRespiratory support
TACOPotentially 6% in critically ill patientsShortness of breath, rapid breathing, or coughDuring or within 4–6 hoursPotentially fatalPerson needs to sit upright and diuretics

Delayed reactions

Delayed hemolytic or delayed serologic transfusion reaction1 in 2500Fever, jaundice, dark urine, stomach pain, labored breathing, high blood pressure3–10 daysMildClose monitoring and hydration
TAGVHDExact prevalence is unknown, but the reaction is very rareRash, abdominal pain, nausea, vomiting, fever, and bone marrow failure2 days to 6 weeks after transfusionPotentially fatalPrevention: Irradiation of blood products
PTP1 in 25,000–100,000Low platelet count and bleeding5–10 daysPotentially fatalSupportive using IV immunoglobin an steroids

The outlook depends on which reaction a person is experiencing. However, serious blood transfusion reactions are uncommon.

Healthcare providers, blood banks, and hospitals take many precautions to help reduce the chance of a transfusion reaction from occurring.

Depending on the type of transfusion reaction, complications can include:

  • renal failure
  • lung injury
  • blood clots

A person should notify a healthcare professional if they experience any of the symptoms mentioned in this article.

A person can learn more about the potential risks and complications here.

According to the CDC, doctors transfuse 17.2 million blood product units each year in the United States, and most people do not experience any blood transfusion reactions.

If someone has a blood transfusion and experiences symptoms, such as shortness of breath, low blood pressure, red or brown urine, flank pain, or other serious side effects, they should see a doctor immediately.


Can a person do anything to help reduce the chance of a blood transfusion reaction from occurring?


No, unfortunately, you cannot reduce your chances of having a blood transfusion reaction. However, if you have had one previously, then you should let your doctor know before receiving another transfusion. Also, you should let your doctor and healthcare team know if you have had previous transfusions so they can look out for any reactions.

Alana Biggers, MD. MPH

Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

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