Blood Transfusion Side Effects and Safety
Most people who get a blood transfusion (or blood product transfusion) have no problems, but some people do. These are called transfusion reactions.
In addition, some people might worry about blood transfusion safety. There are safety protocols in place, and the chance of getting an infection from a blood transfusion in the US is very low.
Transfusion reactions
There are several types of transfusion reactions. Some are mild and don’t need treatment. Others are more serious. Most transfusion reactions happen during the transfusion, but others might not happen for several days.
Tell your doctor or nurse right away if you have:
- Itching, hives, or rash
- Swelling in your face, lips, or tongue
- Headache or dizziness
- Fever or chills
- Trouble breathing or new cough
- Chest or back pain
Allergic reactions
This is the most common transfusion reaction. It is usually mild, with itching or hives, but in some cases it can be severe.
It happens when your immune system reacts to proteins in the blood product. Antihistamine medicine is usually enough to treat the reaction. If there are no other symptoms, the transfusion is usually continued.
Febrile reactions
This is a common reaction that happens when your immune system reacts to white blood cells (WBCs) in the blood product. It can occur during the transfusion or up to 24 hours afterward.
You may have a fever, headache, nausea, chills, or a general feeling of discomfort. Acetaminophen (Tylenol) can help. If the fever happens during the transfusion, is mild, and doesn’t include other symptoms, the transfusion may be continued.
People who are at risk for a febrile reaction may be given leukoreduced blood products (white blood cells removed) to help prevent these reactions.
Transfusion-related acute lung injury (TRALI)
This is a very rare reaction and usually happens to people who are very sick in the hospital. The main symptom is trouble breathing.
Acute hemolytic reaction
This is a very rare but serious reaction that develops when the donor and recipient blood types don’t match. It usually happens quickly, within a few minutes after the transfusion starts. This is why so many safety checks are done to make sure the right blood goes to the right person.
Delayed hemolytic reaction
This kind of reaction usually only happens if a person has had many transfusions in the past. The body slowly attacks proteins on the transfused donor cells. If you’ve had many past transfusions, extra testing can be done to match blood products and help prevent future reactions.
Graft-versus-host disease (GVHD)
This only happens in people with a very weak immune system, like after a stem cell or bone marrow transplant, or an organ transplant. In this reaction, the white blood cells of the donor blood attack the tissues of the person getting the transfusion.
To prevent GVHD, donated blood can be treated with radiation before transfusion (irradiated blood products).
Infections
The chance of getting an infection from a blood transfusion in the US is very low. All blood donors are screened and all blood products are tested for the following infections:
- Hepatitis B virus
- Hepatitis C virus
- Human immunodeficiency virus (HIV)
- Syphilis
- HTLV-I and HTLV-II
- West Nile virus
- Chagas disease
Some states require other tests depending on common infections in that area. More tests may also be ordered. For example, some people need cytomegalovirus (CMV)-negative blood products.
Bacterial contamination
Rarely, tiny amounts of skin bacteria get into the blood during donation. Platelets have the highest risk of bacterial contamination because they are kept at room temperature. Other blood products are refrigerated or frozen, which lowers the chance of bacteria growing.
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- References
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
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Centers for Disease Control and Prevention (CDC). Transfusion complications monitoring. Updated May 15, 2024. Accessed at https://www.cdc.gov/sickle-cell-research/php/transfusion-complications/ on July 15, 2025.
Taheri Soodejani M, Haghdoost AA, Okhovati M, et al. Incidence of adverse reaction in blood donation: a systematic review. Am J Blood Res. 2020;10(5):145-150.
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Last Revised: August 22, 2025
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