Q: How much blood is taken?

A: For a whole blood donation, approximately one pint (500 ml) of blood is collected. For donations of other blood products, such as platelet or plasma, the amount collected depends on your height, weight and platelet count.


Q: Are the history questions necessary every time I donate?

A: Yes, since this helps to ensure the safest possible blood supply. All donors must be asked the screening questions at each donation. Both AABB and FDA regulations specifically require that all blood donors complete the donor history questionnaire on the day of donation and prior to donating.


Q: What does the term “donor deferral” mean?

A: Donor deferral means that an individual is not eligible to donate based on the criteria used to protect the health and safety of both the donor and transfusion recipient. A prospective donor may be deferred at any point during the collection and testing process. The period of time a person will not be eligible to donate depends on the specific reason for deferral. After the deferral period ends, a donor can return to the blood donor center to be reevaluated and resume donation if all donor eligibility criteria are met.


Houston Methodist Blood Donor Center follows donor eligibility criteria based on requirements of the FDA, AABB Standards, and their own local policies. The medical director has ultimate authority to establish a more stringent deferral policy based on their clinical judgement as a physician.


Q: If I was deferred once before, am I still ineligible to donate?

A: Houston Methodist Blood Donor Center will inform you if you are permanently deferred or temporarily deferred. The deferral time depends upon the reason for deferral. Prior to each donation, you will be given a mini-physical and medical interview. At that time, it will be determined if you are eligible to donate blood on that day.


Q: If I just received a flu shot, can I donate blood?

A: Yes. There is no waiting period to donate after receiving a flu shot.


Q: If I have a cold or the flu, can I donate blood?

A: No, blood centers require that you be in good health (symptom-free) and feeling well.


Q: Can I still donate if I have high blood pressure?

A: Yes, if your blood pressure falls within the limits set by FDA regulations.


Q: What if I'm taking aspirin or medication prescribed by my doctor?

A: We recommend that you call the blood donor center ahead of time to inquire about any medications you are taking. Aspirin and ibuprofen will not affect a whole blood donation. However, apheresis platelet products can be affected if aspirin or aspirin products are taken 48 hours prior to donation. Many other medications are acceptable.

Q: How long will the actual donation process take?

A: The entire donation process, from registration to post-donation refreshments, takes about 45 minutes. The actual donation takes about 5-10 minutes.


Q: What is apheresis?

A: Apheresis, an increasingly common procedure, is the process of removing a specific component of the blood, such as platelets, red blood cells, plasma (liquid part of the blood) and returning the remaining components to the donor. This process allows more of one particular part of the blood to be collected than could be separated from a unit of whole blood.

The apheresis donation procedure takes longer than that of a whole blood donation. A whole blood donation takes about 20 minutes to collect the blood as compared to an apheresis donation which may take about one to two hours, depending on the blood component(s) that is being donated.


Q: What types of tests are performed on donated blood?

A: After blood is drawn, it is tested for ABO group (blood type) and Rh type (positive or negative), as well as for any unexpected red blood cell antibodies that may cause problems for the transfusion recipient. Blood is tested for:

  • Hepatitis B virus
  • Hepatitis C virus
  • HIV-1 and HIV-2
  • HTLV-I and HTLV-II
  • Syphilis
  • West Nile virus
  • Trypanosoma cruzi, the infectious agent causing Chagas' disease
  • Babesia – in states where testing is required by FDA guidance


Q: Does donated blood stay on the shelf indefinitely until it is used?

A: No. Each unit of whole blood is separated into several components. Red blood cells may be stored under refrigeration for a maximum of 42 days. Platelets are stored at room temperature and may be kept for a maximum of five to seven days. Fresh frozen plasma is kept in a stored frozen state for up to one year. 


Q: Is there such thing as artificial blood?

A: Scientists have yet to find a successful substitute for human blood. This is why blood donors are so vital to the lives of those who are in need of blood.


Q: Who needs blood?

A: The need for blood is great. Every day in the U.S., approximately 29,000 units of red blood cells are required in hospitals and emergency treatment facilities for patients with cancer and other diseases, for organ transplant recipients, and to help save the lives of accident/trauma victims. In addition, nearly 5,000 platelet units and 6,500 units of plasma are also needed. In 2017, nearly 16 million blood components were transfused. With an aging population and advances in medical treatments and procedures requiring blood transfusions, there is always a need for blood and blood components.


Q: What is the most common blood type?

A: The approximate distribution of blood types in the U.S. blood donor population is as follows. Distribution may be different for specific racial and ethnic groups and in different parts of the country:

  • O Rh-positive --- 39 percent
  • O Rh-negative ---  9 percent
  • A Rh-positive --- 30 percent
  • A Rh-negative ---  6 percent
  • B Rh-positive ---    9 percent
  • B Rh-negative ---   2 percent
  • AB Rh-positive ---  4 percent
  • AB Rh-negative --- 1 percent


In an emergency, anyone can receive type O red blood cells. Therefore, people with type O blood are known as "universal donors." In addition, individuals of all types can receive type AB plasma.