Blood Donor Center

Find answers to frequently asked questions about donating blood at Massachusetts General Hospital.

Frequently Asked Questions About Donating Blood

How much blood is taken during a blood donation?

A little less than one pint of blood is taken for each whole blood donation.

How much blood is in my body?

The average adult has between nine and 12 pints of blood, depending on the person’s weight.

How long will it take my body to replenish my lost blood?

The blood volume is typically replaced within 24 hours. Red blood cells take between four to six weeks for complete replacement, which is why the FDA requires an eight-week wait between blood donations. Your body will not be affected adversely by the loss of the pint of blood.

How will I feel after donating blood?

You’ll feel fine! Regular activities can generally be resumed right away. After donation you are invited to have some juice and snacks to help replace the volume and to give you a bit of time to relax.

Why should I give blood? Aren’t there plenty of people who do that?

There is a need for new blood every day. Less than 5 percent of the eligible population donates. However, more than 90 percent of the population will need blood in their lifetime.

Who uses my blood?

Your donated blood could go to a newborn just fighting to stay alive, a young child battling leukemia, a teen in a car accident, a young man with anemia, a middle-aged woman with a bleeding ulcer or an elderly person having cardiac surgery. You never know who might get your blood, but know that your blood will always be used to help someone in need.

What happens to my blood after I donate?

Your donation will be typed and tested for 10 infectious diseases. Once the blood passes all of the tests, it will be broken down into its components (red blood cells, plasma and platelets).

Does it hurt to donate blood?

The main obstacle to donating blood is worrying about how it will feel. You will feel only a slight pinch at first and then nothing.

How long does donating blood take?

If you schedule an appointment, the entire process will take about 30-40 minutes (for whole blood donations). The actual donation takes about five to seven minutes.

What is the most needed type of blood?

All types of blood are needed. Type O is the most common blood type and is the most widely used and needed. Type O can safely be transfused to all other types and is frequently used in emergencies. It’s best, however, to use a patient’s specific blood type for transfusions.

Why should I donate blood?

The answer is simple – you could save someone's life! Blood can only be given from one person to another – no other source is currently available. Volunteer blood donors are needed on a daily basis to give blood for the thousands of patients who need it.

Why do minority populations especially need to donate blood?

There is a greater amount of blood types O and B in minority populations than in Caucasians. Because large amounts of blood are needed to treat Sickle Cell disease, which appears primarily in minority populations, there is a growing need for minority blood donors.

Of the 5 percent of the population that donates blood, only 10 percent are African American or Hispanic. During transfusions the patient's blood must match as closely as possible in both the type and specific antigens of the blood being transfused. Because we inherit certain antigens from our ancestors, someone of the same race and ethnicity is found to be a better match for them.