Patient education: Blood donation (giving blood) (The Basics)

What is blood donation? — Blood donation is the medical term for when a person gives (donates) blood. A person who donates blood is called a blood donor. In the US, people do not get paid for giving blood. People who give blood do it because they want to. The amount of blood removed during a donation is called a "unit."

When a person gives blood, their blood goes to a "blood bank," or specialized laboratory. There, it is tested, made ready for use, and stored until it is needed. Hospitals can get blood from a blood bank to give to patients who need it. When a person gets donated blood, it is called a "blood transfusion."

Who might need donated blood? — People might need donated blood if they:

●Lose a lot of blood in an accident or during surgery

●Have a medical condition that affects their blood

Some people have their own blood drawn and stored if they are planning to have surgery soon. That way, if they need blood during surgery, they can get their own blood. But this is not very common.

Who can give blood? — In the US, people can give blood if they:

●Are at least 16 or 17 years old (depending on the state)

●Are healthy

●Weigh at least 110 pounds (about 50 kg)

People should not give blood if they:

●Take certain medicines

●Have an infection or fever

●Have iron deficiency

●Are pregnant

●Have exchanged sex for money or have other risk factors for HIV

The donation center will have a list of exactly what things mean that you cannot give blood. Some of these rules are to protect the person giving blood. Others are to protect the person who gets the blood.

Some people want to give blood because they know that their blood will be tested, and they want to know if they have certain infections, such as HIV or hepatitis C. People should not give blood as a way to get tested for these infections. Doing this could increase the risk of the person who receives the blood getting an infection. If you want to be tested for HIV or hepatitis C, speak with your doctor.

To check that you meet all of the conditions for giving blood, a trained staff person will ask you questions and make sure that you are healthy enough to donate.

Where can I give blood? — You can find information online about where to give blood in your area. Check with:

●Your community blood center

●American Red Cross (www.redcrossblood.org or 1-800-733-2767)

●Association for the Advancement of Blood & Biotherapies ("AABB") (www.aabb.org or 301-907-6977)

●OneBlood (www.oneblood.org)

●America's Blood Centers (www.americasblood.org or 202-393-5725)

●Versiti (www.versiti.org)

●Vitalant (www.vitalant.org or 1-877-258-4825)

What questions will I be asked before I give blood? — A staff person will ask you questions about:

●Whether you are feeling sick – You can't give blood if you don't feel well or have a fever.

●Medical conditions you have or had, including cancer and severe heart or lung disease

●Medicines you are taking – Some medicines can be dangerous for the person who receives the blood.

●Any recent vaccines you have gotten

●Whether you have been exposed to certain infections, like HIV, malaria, or hepatitis

●Countries you have lived in or traveled to.

●Sex partners you have had – This includes how many partners and whether any are new, as well as sex practices such as anal sex.

●Any tattoos or body piercings

●Any drug use

●Your weight

●Your last blood donation – People need to wait a certain amount of time before they can give blood again.

What else will happen before I give blood? — The staff person will check your temperature, blood pressure, and pulse (heartbeat).

They will take a small amount of blood from your fingertip to make sure that there is enough hemoglobin in your blood. (Hemoglobin helps red blood cells carry oxygen to all parts of the body.) When there is too little hemoglobin in the blood, this is called "anemia." People with anemia might feel fine, or they might feel tired or weak. If your hemoglobin is too low, you won't be able to give blood, and you might need treatment. This test will not be able to tell if you have low iron, which is a common cause of anemia.

What happens when I give blood? — When it is time to give blood:

●You will sit or lie back in a comfortable chair. The staff person will put a needle in your arm. The needle will stay in place while blood is collected from your arm (figure 1). Giving blood takes about 15 minutes or less.

●After you give blood, you will get some snacks and drinks. They will also watch you for a short time to make sure that you don't have any side effects.

●Before you leave, a staff person will give you a phone number to call in case you have any problems or questions. Call this number if you wish to correct any answers to the questions about medicines, medical history, or risks for infection. You should also call if you remember something that you did not think of or did not feel comfortable sharing at the time.

What side effects can I have from giving blood? — The most common side effects include:

●Getting a bruise or feeling sore where the needle went in the skin

●Feeling tired after

Some people can feel faint or pass out. This is more likely to happen if it is your first time giving blood, if you are young, or if your weight is low. To help prevent feeling faint or passing out, drink water before you give blood.

After you give blood, your body will make new blood to replace it. This takes a little while. Most people need to wait at least 8 weeks before they are allowed to donate blood again. Some people take extra iron to help them make more blood. If you are a teen, were recently pregnant, have monthly periods, or donate blood a few times a year, it might be a good idea to take iron as part of a daily multivitamin. But you should talk with your doctor before trying this, because some people have high iron levels and should not take extra iron.

Will my donated blood be tested for problems? — Your blood will be tested for some problems, but not all. All donated blood is tested for certain viruses. Some of these include HIV, hepatitis B, hepatitis C, and West Nile virus. Blood is also tested for the bacteria that cause syphilis.

If tests of your blood show that you might have an infection, the blood bank will let you know. They will also safely throw away your blood. However, do not to give blood as a way to get tested for these infections. Doing this could put another person at risk, and it might not be the best test for your situation.

Blood is not tested for the virus that causes COVID-19. That's because most viruses that affect the lungs are not spread through blood. Do not try to give blood if you think that you have COVID-19. This can expose other people to illness.

Donated blood is not tested for other things like iron levels, cancer, diabetes, or cholesterol.

What if I get sick after I give blood? — If you get sick within a few days of giving blood, call the number that the staff person gave you. Depending on your symptoms, the blood bank might throw away your blood so it doesn't infect anyone else.

More on this topic

Patient education: Blood transfusion (The Basics)
Patient education: HIV/AIDS (The Basics)
Patient education: Hepatitis B (The Basics)
Patient education: Hepatitis C (The Basics)
Patient education: Blood type test (The Basics)

Patient education: Blood donation and transfusion (Beyond the Basics)