Why Do People Need Blood Transfusions?

Table of Contents
View All
Table of Contents

If you can't make enough blood cells or you lose too much blood at once, you may need a blood transfusion. If you are going into surgery that is likely to involve blood loss, you may anticipate this. Or, you may require one unexpectedly due to an accident or an illness. In the United States, blood transfusions save millions of lives each year.

This article will discuss why people need to undergo blood transfusions, what to expect before, during, and after one, and possible complications.

Donated blood bags in a storage refrigerator

ozgurdonmaz / Getty Images

Why Blood Transfusions Happen

A blood transfusion treats specific problems. Some typical reasons you may need one include:

  • You've experienced bleeding and lost a great deal of blood, possibly due to an accident or surgery.
  • You're unable to make enough blood, especially red blood cells, and you've become anemic, lacking enough healthy red blood cells to carry oxygen.
  • You have a genetic condition and you don't produce enough healthy blood cells.

Components in Transfused Blood

Aside from a whole blood transfusion, you can receive different components of one. These include red blood cells (which carry oxygen), platelets (cells involved in clotting), plasma (the liquid part of whole blood), albumin (a type of protein), or gamma globulin (immune system proteins). Your healthcare provider can transfuse the components you need.

Blood Transfusion Procedure

Blood transfusions may intimidate you if you've never undergone one. The transfusion will usually take place at your healthcare provider's office, a clinic, or a hospital. Here's what to expect.


Before a blood transfusion, your healthcare provider will draw your blood and send it to a lab to type and match it with any blood products to transfuse. The laboratory's blood bank professionals will ensure they label each unit with your identification.

A healthcare provider will check your vital statistics, such as your temperature, pulse, and pressure to ensure that you are a reasonable candidate for receiving blood. If there is a reason why you aren't, they will promptly explain why.

Autologous Blood Transfusions

When planning for an upcoming surgery, you may be eligible to donate your own blood to store and then transfuse back into you if necessary. This is called an autologous transfusion.


A healthcare provider will place an intravenous (IV) line (likely in your arm) to enable you to receive the donated blood. You will either sit for this or lie down. They will ensure your identification matches the identification on the transfused blood products.

The blood for the transfusion will drip from a bag through the IV line into your vein. Completing this process can take up to four hours.


When you've received all the blood you need, your healthcare provider will remove the IV line and check your blood pressure and other vital signs. Assuming you're only receiving a blood transfusion, you should be able to go home shortly afterward and resume your normal activities.

Remember that even if all your levels meet expectations, you may experience some side effects. For example, for a few days, your arm may feel sore in the area where the IV was.

To help ensure that you are reaping the benefits of the transfusion, your healthcare provider may order blood tests in the days after the transfusion.

Depending on why you underwent the transfusion, you should begin to feel the positive effects within the first 24 hours.

Can You Refuse a Blood Transfusion?

An adult can opt against having a blood transfusion even if it means they may ultimately die.

But if the patient is still a minor, a healthcare provider can insist on doing the transfusion if the minor's refusal to undergo the transfusion will cause severe injury or death.

Risks and Complications

Though blood transfusions rarely present any issues, every once in a while, one may lead to complications, such as:

  • Allergy: You may have an allergic reaction even if the blood you receive is the correct type. Symptoms may include hives or itching. Report this to your healthcare provider. Most of the time, you can manage this with antihistamine medication.
  • Fever: Developing a fever after a transfusion is rarely a significant issue. Your body may respond to the presence of white blood cells in the transfused blood by increasing your body temperature. However, if you experience any chest pain or nausea, contact a healthcare provider to determine what's happening.
  • Infection: All blood donors and donated blood are screened for signs of transmissible illness. Still, on rare occasions, viruses, bacteria, or parasites may evade detection. If this happens, you may become ill from the transfusion. But keep in mind that this is very much the exception, not the rule.
  • Hemolytic transfusion reaction: In rare instances, the body attacks the transfused red blood cells because they are of an incompatible type. This is most often due to clerical errors or errors in identifying who is to receive the transfusion. Symptoms include fever, chills, dark urine, or pain in the lower back or chest.
  • Transfusion-related acute lung injury (TRALI): This reaction, in which fluid accumulates in the lung (edema), can happen in the hours after a transfusion. Symptoms include difficulty breathing, low blood pressure, and fever. Research suggests that this may result from antibodies in the donor blood's plasma reacting with the recipient's white blood cells.

Likelihood of Complications

In the United States, the chance of having an adverse reaction to a blood transfusion is 0.2%. In 80% of cases, it is either an allergic reaction or a fever caused by white blood cells in the transfusion.

Post-Transfusion Reactions

In most instances, any reaction to a blood transfusion will occur right away. But sometimes, such adverse reactions may happen down the line.

A delayed hemolytic reaction may arise within eight days of the transfusion, but this can take place up to two weeks later. Here, the person develops antibodies to the transfused red cells. These antibodies may be too weak for initial detection to pick up. Usually, this can occur in those who are pregnant or who previously underwent a transfusion.

If you have such a reaction, it's particularly important to ensure that going forward, any transfused blood does not contain the same antigen (a compound in blood cells that can trigger an immune reaction) that you reacted to initially.

Transfusion-associated graft-versus-host disease is a very rare complication that can occur months after transfusion. In this case, white blood cells in the transfused blood (called T-cells) multiply and attack the recipient's tissues.

The Truth About HIV Blood Transmission

All blood donations in the United States undergo thorough screening and testing for HIV. The American Red Cross estimates there is a 1 in 2 million chance that a unit of donated blood contains HIV and is capable of transmitting it to a recipient. Though this is still technically a possibility, it almost never occurs.

Blood Transfusions Can Save Lives

Transfusions save lives round the clock. In the United States, a person needs blood or platelets every 2 seconds. Such transfusions can help save the lives of a variety of individuals, including;

  • People who have been in an accident, such as a car crash, and may require as much as 100 units of blood
  • Those undergoing surgery where there may be extensive blood loss
  • Individuals with sickle-cell anemia who require transfusions throughout their lives
  • People with cancer who may not make enough blood cells or may have internal bleeding and need transfusions to replace those cells (people without adequate red blood cells may feel dizzy, out of breath, and tired)


Anyone may need a blood transfusion, sometimes without warning. Having one after an accident, illness, or surgical procedure can save your life. If you are a candidate for a transfusion, the procedure itself usually takes a maximum of four hours, and you may begin to feel better within a day or so.

Afterward, you may have little more than a sore arm. In some cases, there you may experience side effects such as fever, infection, or an allergic reaction. Contact a healthcare provider immediately with any concerning symptoms.

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Cancer Society. Every cancer. Every life.

  2. NHS Inform. Blood transfusion.

  3. American Red Cross. Types of blood transfusions.

  4. NHS. Advice for patients following a blood transfusion.

  5. UConn Health. Clinical policy: refusal of blood transfusion and/or blood products.

  6. American Red Cross. Risks & complications.

  7. Noor NHM, Joibe KF, Hasan MN. Prevalence of near-miss events of transfusion practice and its associated factors amongst house officers in a teaching hospital. Oman Med J. 2021;36(2):e249. doi:10.5001/omj.2021.55

  8. Perez-Viloria ME, Lopez K, Malik F, Yatham P, Lopez O, Oh KS, Alghamdi S, Garcia G. Transfusion-related acute lung injury (TRALI) in postoperative anesthesia care unit (PACU) after one unit of platelets: a case report. Cureus. 2022;14(9):e29274. doi:10.7759/cureus.29274

  9. Harvey AR, Basavaraju SV, Chung KW, Kuehnert MJ. Transfusion-related adverse reactions reported to the National Healthcare Safety Network Hemovigilance Module, United States, 2010 to 2012. Transfusion. 2015;55(4):709-718. doi:10.1111/trf.12918

  10. Omer SA, Alaesh JS, Algadeeb KB. Delayed hemolytic transfusion reaction in a patient with sickle cell disease: case report. Int Med Case Rep J. 2020;13:307-311. doi:10.2147/IMCRJ.S257036

  11. Manduzio P. Transfusion-associated graft-versus-host disease: a concise review. Hematol Rep. 2018;10(4):7724. doi:10.4081/hr.2018.7724

  12. American Red Cross. Importance of the blood supply.

By Maxine Lipner
Maxine Lipner is a long-time health and medical writer with over 30 years of experience covering ophthalmology, oncology, and general health and wellness.