Many people are encouraged to give blood, which can be a lifesaving measure, especially if you have a rare blood type. If you are accepted as a blood donor, you will be seated in a chair while a needle is inserted to collect your blood, and you will be offered a light snack afterwards to prevent the feelings of dizziness that people sometimes experience after giving blood. Giving blood is a wonderful charitable act and it is also relatively easy and pain free; most major areas have a blood donation center which is always open, and many blood banks sponsor blood collection drives with mobile stations for donors on the go.
Because blood products are transfused into the bodies of other people, certain medical conditions will preclude you from giving blood, because of the risk of transmitting something to someone else. In other cases, waiting periods for giving blood have been established to make sure that you are free of potentially harmful substances. All blood donors go through a pre-screening questionnaire, to make sure that they are eligible, and you should always answer the questions honestly and to the best of your knowledge before giving blood. Although all donated blood is screened before entering the blood bank, screening is expensive, and excluding potentially tainted blood before it is collected is safe, sensible, and cost efficient.
If you have certain conditions or have engaged in intravenous drug use, you are totally ineligible to give blood. These conditions include blood borne diseases like Hepatitis C, AIDS, and some STDs. If you have an active infection anywhere on your body, have the cold or a flu, have a blood condition such as hemophilia or hemochromatosis, have signs of jaundice, or have been exposed to Creutzfeldt-Jakob Disease, you will be asked to refrain from giving blood. For your own safety, if you are pregnant, your weight is below 110 pounds (50 kilograms), are anemic, have high blood pressure, or a high temperature, you will be asked to return at a later date. Do not be offended if you are rejected from giving blood for any of these reasons: blood bank staff care about your safety as well as patient health.
In other instances, a waiting period is required, to make sure that your blood is safe to use. If you have been vaccinated recently for smallpox, measles, polio, or hepatitis B, you are asked to wait for a period ranging from two weeks to two months. If you have had cancer, received a new organ, or a blood transfusion, you must wait at least a year to give blood. People who have traveled or lived in countries with malaria are also asked to wait before giving blood, to make sure that malaria is not passed on to a sick patient. Waiting period requirements change, depending on the global health situation: people who have eaten meat in Britain, for example, are currently excluded from giving blood due to concerns about prions from bovine spongiform encephalitis. If there is a major disease outbreak somewhere in the world, recent visitors to that area should refrain from giving blood for at least one year, to keep the blood supply safe and clean.