Blood donors are heroes. By donating blood you can save a life. That's because no chemical, drug or fluid can replace blood in a real emergency. Blood collections are rising, which is good news. The bad news is, the demand is increasing faster than collections, and the nation's blood banks are facing persistent supply problems, national blood-supply groups say.

Donations traditionally slump during the Christmas holiday season, as colleges, schools and businesses that normally host blood drives close and families take vacations. An outbreak of influenza and bad weather also can affect donations.

Maintaining an adequate amount of blood for surgeries, trauma victims and treatment of diseases can be problematic.

Every day about 38,000 units of red blood cells are given to Americans. Blood transfusions are used for trauma victims, patients needing surgery, and those getting treatment for leukemia, cancer or sickle cell anemia.

Why is blood use rising?

About 4.5 million people receive blood transfusions in the United States every year, and that number is expected to rise for several reasons:

• As the U.S. population grows older, the number of surgeries that require transfusions (heart, knee-replacement, and hip-replacement operations, for example) will likely rise as well.
• Procedures and surgeries that require numerous transfusions are becoming more common. A bone-marrow transplant patient needs three weeks of transfusions, and a person undergoing a liver-transplant operation requires 20 units of blood or more.

The basics of blood donation

Blood is separated into three components: red blood cells, which can be stored for 42 days; platelets, which last five days, and plasma, which can be frozen for as long as one year. You can give blood every eight weeks, plasma twice a week and platelets 24 times a year. Type O blood is the most commonly used because it can be safely transfused to people of all blood types.

Here are some guidelines for donating blood:

• You must be at least 17 years old, weigh at least 110 pounds and be in good health.
• People who have spent long periods in the United Kingdom and other countries where Mad Cow Disease is found may not be eligible to donate.
• You need to wait 12 months after travel in an area where malaria is found or wait 3 years after living in a country where malaria is found.
• Should wait 12 months after a tattoo if the tattoo was applied in a state that does not regulate tattoo facilities. This requirement is related to concerns about hepatitis.
• Donating blood takes about 45 minutes to one hour, including 20 minutes for the actual collection. You'll first be asked about your medical history and past behavior to determine if you could be ineligible for various reasons, such as possible HIV infection, intravenous drug use or viral hepatitis.
• Blood is not accepted from sick people as a precautionary measure, but there's no rush if you're ill because blood centers need a steady flow of donors.
• There is almost no risk to donating blood. Less than 10 percent of your blood is removed and the body quickly makes new blood to replace it. A few people may feel faint after donating blood, but this goes away with lying down and drinking fluids.

Who should wait to donate or not donate blood

• You have received a blood transfusion from another person in the United States.
• You received a blood transfusion in certain countries in Africa since 1977.
• You had leukemia or lymphoma, including Hodgkin's Disease.
• You are taking any "blood thinner" (such as coumadin or heparin).
• You have a fever or a productive cough (bringing up phlegm).
• You had hepatitis (inflammation of the liver) caused by a virus, or unexplained jaundice (yellow discoloration of the skin), since age 11.
• You have AIDS or have ever had a positive HIV test, or if you have done something that puts you at risk for becoming infected with HIV.
• You have ever received clotting factor concentrates.
• You have active tuberculosis or treatment for same.
• You have engaged in sex for money or drugs since 1977.
• You have had hepatitis since his or her 11th birthday.
• Other circumstances may make you ineligible to give blood.

To make a donation, call the national Red Cross hotline at 1-800-GIVE-LIFE, America's Blood Centers at 1-888-256-6388 or the AABC at 1-866-376-6968.

America's Blood Centers has a national educational program - called My Blood, Your Blood (www.mybloodyourblood.org) - to teach children and teens about the importance of giving blood.

External Sources American Red Cross America's Blood Centers AABC

This article was reviewed and updated June 2007.