Donating a pint of blood takes about an hour and can save the lives of up to three sick or injured patients. Blood donation is safe in the United States, according to the American Red Cross, and it cannot transmit disease to the donor. Minor problems may occur, but individuals who take steps to avoid these risks usually donate without any negative effects.
Hypotension
Low blood pressure -- also known as hypotension -- may cause donors to feel faint, lightheaded or dizzy during or after the donation process. Causes of dizziness or fainting include dehydration, hunger, anxiety or illness. To avoid a reaction, donors should get a good night's sleep, drink plenty of water or other fluids and eat a well-balanced meal before donating. Afterward, donors must drink juice, eat a snack and stay in the canteen area for at least 15 minutes to ensure that they feel well before leaving. Screening prior to donation excludes individuals who don't feel well, have a fever or have high or low blood pressure.
Fatigue
Donors may experience minor fatigue after donating blood because of the reduced amount of red blood cells in the body. An individual donates about 1 pt. of blood at a blood drive -- just a fraction of the 10 to 12 pts. in an adult's body -- according to the American Association of Blood Banks. The body replaces the plasma or fluid in the blood within about 24 hours, but red blood cells take about four to six weeks for complete replacement, reports the American Red Cross. Donors are instructed to avoid strenuous activity for 24 hours after a donation, drink plenty of non-alcoholic fluids, eat healthy meals, and wait at least 56 days before donating blood again to support the replacement process.
Venipuncture Injury
Blood collection professionals must use a relatively large needle to avoid damaging red blood cells, so some donors may experience temporary pain, bruising or clotting at the needle insertion site. Applying firm pressure after removing the needle, avoiding heavy lifting and leaving the elastic bandage in place for at least 4 hours afterward helps to prevent bruises and blood clots. Nerve damage occurs rarely and requires medical attention.
