A blood donor is a person who voluntarily has blood drawn for the purpose of transfusion. In almost all cases, blood donors are not paid for their donation. A blood donor may donate blood for an unknown recipient, which is called allogeneic (or homologous) donation; for a family member or friend with a matching blood type, known as a directed donation; or for themselves, to be used during a surgical procedure, known as autologous donation. Blood donors may donate whole blood, platelets, or plasma.
Rules vary per country as to who is eligible to donate blood. Usually, blood donors must be a certain weight and within a certain age range. If a blood donor is under 18, he or she will typically require parental permission to donate blood. It is usually required that blood donors must not have had surgery, or any piercings or tattoos, within a certain period of time before donating blood. Other restrictions apply as well, and a specific list will be provided at every blood donation center or online.
The frequency of blood donation depends on the type of donation; allogeneic donation may usually only be performed every eight weeks, whereas autologous donation can be done every few days leading up to the surgery. This is because blood has a relatively brief shelf life. The donation of whole blood requires a longer waiting period in between donations than platelets or plasma, as they return to normal levels within the body much more quickly.
Every time a blood donor donates blood, it will be carefully screened for any diseases. In addition, each time a donor decides to give blood, he or she will be likely be asked to fill out a questionnaire, and a small drop of blood will be tested to be sure that his blood count is high enough. A brief medical history and a test of blood pressure and pulse will be taken to ensure donating blood will not be dangerous to the donor's health. If all of the information gathered is found acceptable, the blood donation can begin.
The typical amount donated from one blood donor is approximately 500 milliliters, or one pint. At any point, the human body contains between ten and 12 pints of blood. A typical donation only takes approximately ten minutes, but most donation centers will ask the blood donor to remain at the center for ten to 15 minutes after donating to have some light refreshments, such as juice or a cookie, to prevent feeling faint. It is very safe to donate blood, and can be a vital, lifesaving resource for those who need it.
Prior to donating blood, it is best to drink plenty of fluids and eat a healthy meal approximately one hour before. Restrictions after donating blood are fairly minimal, and generally involve avoiding lifting heavy objects or exercising heavily for one day. Any questions may be answered by the blood donation technicians.