Giving blood in high school was the BEST! Remember getting out of class for two periods, hanging out with all your friends waiting in line, answering all those pre-screening health questions, watching your friends wince when the needle went in, talking to the cute nurse as she treated you like royalty, then being “forced” to sit at the exit table for 15 minutes with all the snacks you could ever want, and the best part — walking around school all day with your battle wound and the “I gave blood today” sticker emblazoned on your chest.

To most of us, giving blood has since lost its illustrious appeal. It’s just “not fun” anymore to go through an hour-long process culminating in getting pricked in the inner elbow just for a sticker and bragging rights. In this post we’ll explore the ins and outs of giving blood.

Fast Facts

There are some 14.6 million blood transfusions per year in the US (2007).

An estimated 43,000 pints of blood are donated each day in Canada and the US.

Red blood cells live approximately 120 days in your circulatory system.


Before you’re even considered to give blood, you must pass certain prerequisites which depend on your state and the blood company. Typically if you’re 17 years or older you can give blood, and you can be 16 if you have your parent’s consent in some states.

You’ll have to meet the height and weight requirements, which typically require you to be 110 pounds. Women need to be heavier, especially if on the shorter side, RedCross’ website has a table: 4’10” women must be 146 pounds, 5’5” women must be at least 115 pounds. 1 pint of blood is about 1 pound, so if you’re 110 pounds, drawing 1 pint from you takes a whopping 1% of your body mass! That’s why it’s dangerous to draw blood from “smaller” individuals.

Furthermore, if you’re on certain medications like finasteride, dutasteride, isotretinoin, certain blood thinners, and others, you’ll also be ineligible. Here’s a full list. If you’ve been traveling abroad, especially in areas with Malaria, Ebola, Malaria, or West Nile virus risk, you may have to wait 28 days or up to a few years to donate. Finally, if you’re pregnant or have given blood within 6 weeks of when you want to donate, you’ll probably get deferred.

You’ll typically need to wait 12 months after getting a tattoo to give blood.

If you’re still unsure if you’re eligible, here’s a long list provided by the American Red Cross. It covers everything from acupuncture to Zika!


You survived round 1! Next comes screening questions! Keeping the national blood supply safe is important to keep recipients healthy; the FDA, blood centers, and hospitals are all held accountable for safe blood. Think of the screening questions as a first line of defense for recipients.

Typical diseases screened for include: Hepatitis BHepatitis CHIVHTLVsyphilisWest Nile virusChagas diseaseCMVMad Cow Disease, and bacterial infections. Your blood will not be used if you have any of these or other dangerous diseases, it will be anonymously tested, and the results will be sent back to you. So screening really saves everyone time.


If you can get through the physical requirements and the 30-minute-long screener questions, then actually giving blood might feel like the easy part.

The person who draws your blood is called a Phlebotomist — now that’s a fun word to say. Phlebo is Greek for “vein,” and tomy is Greek for “to make an incision.” Phlebotomists are trained to stick a needle into a vein, also known as venipunctureBecoming a phlebotomist can take less than a year, and most states do not require certification! So if you’re a vampire or just love blood, go for it!

After you’ve been successfully punctured, a small pump will draw your blood. Drawing 1 pint typically takes about 30 minutes, whereas drawing plasma can take up to two hours.

Drawing plasma takes much longer because your blood is constantly being fed back into you after the plasma has been filtered out, a process called plasmapheresis. Plasma is a clear liquid that makes up 55% of your blood; it’s composed of water, salts, enzymes, antibodies, and other proteins. These chemicals are essential to patients with certain chronic diseases such as immunodeficiency diseases and hemophilia, as well as those with trauma, burns, and shock.

Where does my blood go?

If you’re like the high school me, you probably envisioned your blood being poured into a large vat. Well, luckily that’s not the case.

Blood is generally kept in pint-sized, sterile bags until it is needed. In fact, after your blood is drawn, it’s spun through a centrifuge to separate out the red cells, platelets, and plasma. Furthermore, your plasma may be processed to extract cryoprecipitate, and your white blood cells may be removed to help prevent a bad reaction from the recipient, more on that in a minute.

More and more blood companies are allowing blood tracking features, so you can actually find out exactly who/how your blood is helping the world! You can even give blood to yourself (what?). Yup, giving blood to yourself minimizes the risk of rejection and is not uncommon for those who have an expected surgery where a lot of blood might be lost. It’s called an autologous donation, and it’s not uncommon. There are of course a few extra requirements involved.

Even after all of the screening and filtering mentioned above, anyone cannot give blood to anyone. To summarize a complicated process, there are 8 primary blood types: A+, A-, B+, B-, AB+, AB-, O+, and O-.

Blood type is passed down to you through your parent’s genes. Types A and B are dominant, type O is recessive, so you’re more likely to be type A or B even if one of your parents is type O!

EGA Associates actually had a #FactFriday back in September 2018 with distributions of blood types across Americans:

Who can Give Blood to Who?

First of all, if you have negative (-) blood, you can only receive negative blood. If you have positive blood (+), you can receive positive and negative blood.

Second of all, if you have type A blood you can take type A blood, but not type B blood. Vice versa. And, if you have type AB blood, you can take type A, B, and AB blood.

Types A, B, and AB can also take type O blood. Type O blood cannot take anything but type O blood. In summary, type O- blood can be given to anyone (universal donor), and type AB+ can accept any blood (universal recipient).

If that was confusing, watch this video or check out the table below.

If the incorrect blood type is given to you, your white blood cells might identify the new blood cells as enemies, and they will reject and attack the new red blood cells — called an ABO Incompatibility. This condition can be fatal if not detected quickly.


Blood is in constant demand throughout the US. According to the National Red Cross, some 36,000 units of red blood cells, 7,000 units of platelets, and 10,000 units of plasma are needed every day nationally. Blood only lasts a maximum of 42 days on the shelf, driving the need further.

If you are able, you should give blood! It’s a great way to anonymously help out humanity! Type O is in the strongest demand due to its versatility with patients; in emergencies when there’s no time to check a patient’s blood type, doctors will use O negative blood because anyone can take it, so if you’re O negative go donate!


Believe it or not, you can actually get paid to give blood! If you give plasma twice a week, you might be able to allegedly make up to $300 a month, not including signing bonuses! This is partly because frozen plasma can last up to a year! That’s almost as long as dino-nuggets.

Sketchy Trends and Amazing Heroes

Another growing trend in the blood world: older people buying the blood of younger people for health benefits. These health-tech startups run off of a study from Stanford which showed that blood from younger mice helped cognition and memory of older mice. Companies such as AmbrosiaAlkahest, and the Young Blood Institute are charging up to $285,000 per person to participate, and even some $8,000 per pint (sign me up as a donor!). The FDA and the scientific community have called for the end of these transfusions, shutting down many of these startups. Read the full story here.

One company, Theranos, catapulted from obscurity to having a $9 billion dollar worth, just to crash and burn to a whopping $0 over the course of a few months. Great read. Theranos isn’t the only sketchy blood-related startup, one company claims to be able to run 128 tests on one drop of blood in 15 minutes, another has a 60-second at-home blood test that can check for viruses, infections, and even cancer by using machine learning! Sound too good to be true? Yeah, because it is.

The hero we need. James Harrison, an Australian (not the NFL player), gave blood every week for some 60 years! After going through a serious operation that required donated blood, Harrison pledged to become a lifelong donor, and he did just that until the ripe age of 81! His blood actually contains a rare antibody called anit-D, which helped prevent certain diseases in newborns; his donations contributed to saving some 2.4 million lives!

Have an interesting fact about blood you want to share? Do you have a rare blood type not mentioned? Let us know in the comments!