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Blood donation

Medically reviewed by Last updated on Nov 30, 2023.


Blood donation is a voluntary procedure that can help save lives. There are several types of blood donation. Each type helps meet different medical needs.

Whole blood donation

Whole blood donation is the most common type of blood donation. During this donation, you donate about a pint (about half a liter) of whole blood. The blood is then separated into its components — red cells, plasma and sometimes platelets.


During apheresis, you are hooked up to a machine that collects and separates different parts of your blood. These blood components include red cells, plasma and platelets. The machine then returns the remaining parts of the blood back to you.

Why it's done

You agree to have blood drawn so that it can be given to someone who needs a blood transfusion.

Millions of people need blood transfusions each year. Some may need blood during surgery. Others depend on it after an accident or because they have a disease that requires certain parts of blood. Blood donation makes all of this possible. There is no substitute for human blood — all transfusions use blood from a donor.


Blood donation is safe. New, sterile disposable equipment is used for each donor, so there's no risk of getting a bloodborne infection by donating blood.

Most healthy adults can donate a pint (about half a liter) safely, without health risks. Within a few days of a blood donation, your body replaces the lost fluids. And after two weeks, your body replaces the lost red blood cells.

How you prepare

Eligibility requirements

To be eligible to donate whole blood, plasma or platelets, you must be:

Eligibility requirements differ slightly among different types of blood donation.

Food and medications

Before your blood donation:

What you can expect

Before the procedure

Before you can donate blood, you will be asked to fill out a confidential medical history. It includes questions about behaviors known to carry a higher risk of bloodborne infections — infections that are transmitted through blood.

Because of the risk of bloodborne infections, not everyone can donate blood. The following are groups that are not eligible to donate blood:

You will also have a brief physical exam. The exam includes checking your blood pressure, pulse and temperature. A small sample of blood is taken from a finger prick and is used to check the oxygen-carrying part of your blood (hemoglobin level). If your hemoglobin concentration is within a healthy range, and you've met all the other screening requirements, you can donate blood.

COVID-19 concerns

The virus that causes coronavirus disease 2019 (COVID-19) hasn't been shown to be transmitted through blood transfusions. However, the U.S. Food and Drug Administration suggests waiting to donate blood for at least 10 days after a positive diagnostic test for COVID-19 without symptoms or for at least 10 days after symptoms of COVID-19 have completely gone away.

Those who have tested positive for COVID-19 antibodies but didn't have a diagnostic test and never developed symptoms can donate without a waiting period or having a diagnostic test done before donation.

During the procedure

You lie or sit in a reclining chair with your arm extended on an armrest. If you have a preference for which arm or vein is used, tell the person who is collecting your blood. A blood pressure cuff or tourniquet is placed around your upper arm to fill your veins with more blood. This makes the veins easier to see and easier to insert the needle into. It also helps fill the blood bag more quickly. Then the skin on the inside of your elbow is cleaned.

A new, sterile needle is inserted into a vein in your arm. This needle is attached to a thin, plastic tube and a blood bag. Once the needle is in place, you tighten your fist several times to help the blood flow from the vein. First, blood is collected into tubes for testing. Then blood is allowed to fill the bag, about a pint (about half a liter). The needle is usually in place about 10 minutes. When your donation is finished, the needle is removed, a small bandage is placed on the needle site and a dressing is wrapped around your arm.

Another method of donating blood becoming increasingly common is apheresis. During apheresis, you are hooked up to a machine that can collect and separate different parts of your blood, such as red cells, plasma and platelets. This process allows more of a single component to be collected. It takes longer than standard blood donation — typically up to two hours.

After the procedure

After donating, you sit in an observation area, where you rest and eat a light snack. After 15 minutes, you can leave. After your blood donation:

Contact the blood donor center or your health care provider if you:



Your blood will be tested to determine your blood type and your Rh factor. Blood type is classified as A, B, AB or O. The Rh factor refers to the presence or absence of a specific antigen — a substance capable of stimulating an immune response — in the blood. You'll be classified as Rh positive or Rh negative, meaning you do or don't carry the antigen. This information is important because your blood type and Rh factor must be compatible with the blood type and Rh factor of the person receiving your blood.

Your blood will also be tested for bloodborne diseases, such as hepatitis and HIV. If these tests are negative, the blood is distributed for use. If any of these tests are positive, the donor center notifies you, and your blood donation is discarded.

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