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Blood Donation Process

By Ravindra Sarode, MD, The University of Texas Southwestern Medical Center at Dallas

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Donating blood is very safe. The entire process of donating whole blood (that is, blood with all component cells) takes about 1 hour. Blood donors must be at least 17 years old and weigh at least 110 pounds (50 kilograms). In addition, they must be in good health. Their pulse, blood pressure, and temperature are measured, and a blood sample is tested to check for anemia. They are asked a series of questions about their health, factors that might affect their health, and countries they have visited. Certain conditions and factors can permanently or temporarily disqualify people from donating blood. Disqualifying factors typically are those that might make donation dangerous for the donor or risk transmitting a disorder to the recipient. The decision to accept or disqualify a donor can be complicated. The American Red Cross provides detailed information on their website Red Cross eligibility requirements for blood donation.

Did You Know...

  • Very few disorders permanently disqualify people from giving blood.

  • Most people can eventually give blood even if they are disqualified at first because most conditions that disqualify donors are temporary.

  • Donated blood is tested for many infections, so the chance of getting a disease from donated blood is very small.

Some Conditions That Disqualify People From Donating Blood


Permanent or Temporary Disqualification



Participation in activities that increase the risk of HIV infection

Homosexuality in males


High-risk activities include use of intravenous drugs and sexual intercourse with a person who has HIV infection.

Anemia (a low level of hemoglobin in the blood)


People can donate blood after the anemia resolves.

Asthma, severe


Bleeding disorders, congenital


Cancers involving blood cells (for example, leukemia, lymphoma, or myeloma)


People cannot donate even if they are cancer-free.

Cancers, other


People may donate if they are cancer-free and treatment was completed more than 12 months previously.

People with mild, treatable forms (such as small skin cancers) may be able to donate before 12 months.

Drugs (some), such as acitretin, dutasteride, etretinate, finasteride, and isotretinoin


How long people have to wait depends on the drug.

Most drugs do not disqualify people from donating blood.

Heart disease, severe


Hepatitis, illness


People who have ever had hepatitis due to a virus cannot donate blood.

Hepatitis, exposure to


People must wait 12 months after possible exposure (for example, living with or having sex with a person with hepatitis, being incarcerated in a correctional facility for more than 72 hours, or having a human bite that broke the skin).

High blood pressure


People can donate after their blood pressure is controlled.

Possible exposure to prion diseases, such as variant Creutzfeldt-Jakob disease (also called mad cow disease—see Overview of Prion Diseases)


Exposure may occur when

  • People have used insulin derived from cows.

  • People have spent time in Europe since 1980 (ranging from more than 3 months to 5 years, depending on the country)

  • U.S. military personnel who lived on bases in Europe for more than 6 months during 1980–1996.

Malaria or exposure to malaria


People must wait 1–3 years.



Women must wait 6 weeks after giving birth.

Major surgery if recent




People must wait 12 months.


Temporary or permanent

People who received a transfusion in the United States must wait 12 months.

People who received a transfusion in the United Kingdom since 1980 or in certain African countries since 1977 may not donate.

Vaccines (some)


How long people have to wait depends on the vaccine.

HIV = human immunodeficiency virus.

Generally, donors are not allowed to give blood more than once every 56 days. The practice of paying donors for blood has almost disappeared because it encouraged needy people to present themselves as donors and then sometimes to deny having any conditions that would disqualify them.

A person who is deemed eligible to donate blood sits in a reclining chair or lies on a cot. A health care worker examines the inside surface of the person's elbow and determines which vein to use. After the area immediately surrounding the vein is cleaned thoroughly, a needle is inserted into the vein and temporarily secured with a sterile covering. A stinging sensation is usually felt when the needle is first inserted, but otherwise the procedure is painless. Blood moves through the needle and into a collecting bag. The actual collection of blood takes only about 10 minutes.

The standard unit of donated blood is about 1 pint (about 450 milliliters). Freshly collected blood is sealed in plastic bags containing preservatives and an anticlotting compound. A small sample from each donation is tested for the infectious organisms that cause AIDS, viral hepatitis, selected other viral disorders, and syphilis.

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* This is the Consumer Version. *