Blood transfusions can take 1 to 4 hours. A blood transfusion involves giving you blood from a donor via an intravenous (IV) line. Sometimes, you may receive your own blood if it was collected previously.
Some people need regular transfusions to help with medical conditions. Guidelines say that a blood transfusion should generally take a couple of hours, with a maximum of four hours. This is to prevent the blood from becoming damaged and unsafe.
If you need blood in an emergency, though, you may receive the blood much more quickly than normal. This can be a life-saving measure if you are losing a significant amount of blood. Injuries or surgeries that cause a high amount of blood loss can become emergencies.
What to expect
Before the transfusion
In cases of chronic medical conditions, your doctor will order a blood test called a complete blood count (CBC) to determine if you need a blood transfusion. It takes just a few minutes for blood to be drawn for this test. Results are available anywhere from a few hours to a few days later.
If your situation is an emergency, a doctor will act before waiting for the results of the blood test.
Once your doctor has determined that you need a blood transfusion, a medical professional will draw another blood sample. The sample will be sent to a lab for testing known as blood typing and crossing. This testing can be done in just a few minutes. Knowing your blood type is important. It ensures the type of blood your doctor gives you is a match.
Once your blood has been typed
Your identity will be checked to ensure you are given the correct blood. If you don’t already have an IV inserted, the medical professional will start an IV line. They will administer the blood through this line.
First 15 minutes of transfusion
A nurse will remain with you for at least the first 15 minutes of the transfusion. This is because most reactions with blood transfusions, if they happen, occur immediately. Examples of transfusion reactions include:
- back pain
- difficulty breathing
If you have these symptoms, the transfusion will be stopped immediately.
One to four hours in
If you haven’t had a reaction, the nurse may speed up the rate of the transfusion. If you have a condition that affects your body’s ability to maintain fluid balance, such as congestive heart failure, the transfusion may be slower.
Over the course of the transfusion, your nurse or doctor will check your vital signs frequently. They’ll check your:
- blood pressure
- heart rate
Beyond four hours
If you're continually bleeding, the transfusion will last as long as you're bleeding. If you have gastrointestinal bleeding or are losing blood in surgery, your doctor will try to keep up with the amount of blood loss and replace the blood as needed.
Feeling the effects of the transfusion can depend on:
- the amount of blood you started with
- your overall health
- why you need the transfusion
Ideally, you will start to feel better immediately after receiving the transfusion because your blood is better able to function as it should. Often, doctors will order a follow-up CBC about one hour after the transfusion to determine how the transfusion helped you.
If you have a condition where you are actively losing blood, such as gastrointestinal bleeding, your doctor will often need to treat your condition’s underlying cause before transfusions will have their full effects.
Also, while most transfusion reactions will be immediate, there are longer-term risks associated with blood transfusions. Your doctor will monitor you for both. For more information, read about transfusion reactions.
Blood transfusions are usually intended to support your body until the condition subsides and your body can take over making blood again. The healthy body makes millions of new cells on a minute-by-minute basis. How long the treatment continues depends on why you need transfusions.
Your doctor will continue the transfusions to maintain the correct amount of blood and its components in your body. If your doctor is able to correct the underlying problem, your body will ideally be able take over. From there, you won’t need further transfusions.