Blood donation FAQs

This page has reasons people faint while giving blood or after donating (giving) blood and ways to prevent fainting,

a link to the questions asked before you donate / reasons why you might not be able to donate,

info and links for athletes and scuba divers who want to donate blood,

precautions to take after donating blood,

info on how donating blood can make you healthier,

info on what the donations are needed for

and a phone number / link to make an appointment.

(and see info about organ donating:

Every two seconds someone in the U.S. needs a blood transfusion.

blood donation:
Recent news from the Red Cross: ” A, B, and O are the main blood groups, and if we don’t get more people to donate blood and platelets, hospital shelves may be empty when a critical patient arrives.

Every two seconds, someone in the U.S. needs blood. But for the past four years, new Red Cross donors declined by about 80,000 each year.”

Why do some people faint when they give blood?

According to Men’s Health magazine:

“First, there’s a drop in blood pressure (you just gave up a pint).

Second, there’s emotional stress (blood loss triggers a fight-or-flight response, which directs blood to your muscles, not your brain).

And third, standing up quickly drains blood from your head.”

What can I do to prevent fainting after giving blood?

Follow the instructions of the nurse who drew your blood for what to do after you donate. Even if you feel great, lie around for awhile. Then sit up slowly, sit for awhile, then stand up slowly.

According to Men’s Health magazine:

“I you feel woozy after giving blood, you’re no wimp. About 150,000 people faint or come close to fainting each year. It’s a physiological phenomenon you can counteract by drinking 16 ounces of water about a half hour before giving blood. The water slows heart rate and improves bloodflow, especially to the brain.”

IGivebloodbutton.jpg: Button that says I give blood

How long does it take to donate?

They advertise that it takes about an hour, but it took one hour and fifty-five minutes for us one time, even with an appointment and being a previous donor.

First you may be asked to read info, then you will fill out a couple of forms, answering questions to see if you are okay to donate.

What are the rules about who can donate?

You can read most of the donor eligibility guidelines in advance at:

Remember, the blood donation center you go to may have more rules or some different rules that could stop you from donating. Eligibility guidelines can change suddenly, but when you go in for a donation they will have the most current information. You might have been deferred years ago, but the criteria for donating blood have changed over the years. It is possible that a previously ineligible donor could now be eligible to donate, check out the eligibility requirements.

Here are a few of the commonly asked about eligibility rules:

You must be at least 17 years old to donate to the general blood supply. (This is the rule in California where this website is written and in most other states, although a few allow it at age 16 with parental consent.)

In most states you must weigh 110 pounds.

You can’t donate if you have a temperature of or over 99.5 °

At the time of the donation you need to have blood pressure below 180 systolic/below 100 diastolic, but at least 80/50.

Wait 12 months after a tattoo if it was applied in a state that does not regulate tattoo facilities. (Problems could include reused ink, needles that are not sterile. Hepatitis is easily transmitted through blood donations.)

Okay after acupuncture.

Okay after a piercing IF the instruments used were sterile or single use only.

Wait 12 months following a human bite, if it broke the skin.

In almost all cases, medications will not disqualify you as a blood donor. Your eligibility will be based on the reason that the medication was prescribed. As long as the condition is under control and you are healthy, blood donation is usually permitted.

In most cases, medications for high blood pressure do not disqualify you from donating.

Taking antibiotics to control acne generally does not disqualify you from donating blood. Wait 2 days (or in some cases ten days) after finishing antibiotics for an infection (bacterial or viral).

Acceptable two weeks after starting insulin.

In almost all cases, immunizations will not disqualify you as a blood donor

Women may donate during their menstrual period if feeling well on the day of donation. Women taking birth control pills (oral contraceptives) or on hormone replacement therapy for menopausal symptoms can donate. If you are pregnant you can’t donate and you should wait until at least 6 weeks after giving birth.

Again, the blood center you donate at will have the most current rules.

How do they get the blood out of you?

They will poke you twice, once in a finger to get a drop of blood for an initial test, then when they draw your blood donation.

Okay, yes, this is when it hurts a little, but just for a few seconds. While you lie down on a very large well-padded lounge chair, the nurse puts a needle in a vein in your arm. No, the needle is not the size of a drainpipe.

For some people, if you are warm the vein is easier to find, so if a nurse has had trouble finding yours, keep a sweater on for awhile before the next time. AND drink a bunch of water about a half hour before to increase your blood volume and make your veins easier for the phlebotomist to find. Some phlebotomists have asked me if I want the blood drawn from my left arm, (since I am right handed), but my veins in my right arm are usually bigger, so I tell the phlebotomist to choose the arm that looks easiest for her/him on that day.

Once the needle is in place it doesn’t really hurt and you might not even notice it. Then, when the nurse tells you to, you start squeezing something like a a rubber ball that they give you, once every five seconds. It takes about eight to ten minutes to pump out a pint. Racing to pump blood faster than your friend at the next table is not advised.

There will be one or more nurses in the room the whole time you and other people are donating. If it is your first time they pay special attention to you.

be a lifesaver: words be a lifesaver with a drawing of a package of candy

Can athletes donate blood?

Part of winning is feeling that you are the best, and donating blood can give you a big personal lift, just from knowing you helped save up to three or four lives.

But maybe you shouldn’t donate just before a big game. An article from THE PHYSICIAN AND SPORTSMEDICINE said, in part:

“After donating 450 mL (1 U) of whole blood, plasma volume falls 7% to 13%, then recovers within 24 to 48 hours…Marvin Adner, MD, a hematologist and internist in Framingham, Massachusetts, and medical director of the Boston Marathon, says that blood donation should not be a concern for active people who are not world-class athletes–as long as they are not iron deficient…Donald M. Christie, Jr, MD, an internist and sports physician in Lewiston, Maine, says hydration is the best recovery strategy. Donors need to drink not only what is offered afterward at the blood donation center, they need to aggressively hydrate over the remainder of the day, says Christie, who is an editorial board member of The Physician and Sportsmedicine. “Noting the color of the urine is a good way to gauge hydration status,” he says.

He advises endurance athletes to think of the blood donation day as a rest day, and to tread cautiously the next day because hydration stores may not be replenished and delayed vasovagal effects may occur. Christie says though the performance decrement would be slight in an endurance athlete, blood donation should have virtually no effect on strength or short-burst activities.”

An article in Omega Cycling by Dr P A Lambeti (MBBcH), said, in part:

“A study has been done looking at the effects of blood donation on exercise performance in competitive cyclists. This study evaluated 10 male cyclists before and after phlebotomy (donating blood), to determine the effect of donation of one unit of blood on exercise performance. Each subject underwent maximal exercise testing with oxygen consumption measurement at baseline, 2 hours after phlebotomy, 2 days after phlebotomy, and 7 days after phlebotomy. The results found that maximal performance was decreased for at least one week and that submaximal performance was unaffected by blood donation.

Thus, if you are a competitive cyclist, do not donate blood within 7 – 10 days of a competitive race, as your performance will be compromised. If you are a casual cyclist performing submaximally, you may not experience any deleterious effects apart from a higher heart rate than normal from the day after donating.”

Can scuba divers donate blood?

In the article Diving after Blood Donation
By Dr. David Sawatzky in Diver Magazine, he asked and answered the question:

What are the effects of donating blood on scuba diving?

“For the first few hours/days after donating blood, the person will be more susceptible to fainting and will have a reduced exercise capacity. After the blood volume that was lost in the donation is replaced, the person will no longer be prone to fainting and might actually have a slightly improved exercise capacity. There are theoretical slight increases in the risk of oxygen toxicity and DCS but this change in risk most likely has no practical significance. You should never dive (nor do other strenuous activity) the day of a blood donation and should be sure to drink lots of nonalcoholic fluids after donating blood. It should be okay to do conservative dives the next day but if you want to be absolutely certain you have recovered from the acute effects of donating blood, wait 72 hours.”

How can I get enough iron in my blood to be able to donate blood?

5% of blood donors are temporarily deferred because their hemocrit, the pre-donation test for anemia, was below the recommended 38% minimum. A common cause is a diet poor in iron. It can usually be corrected by increasing the amount of iron-rich food in your diet.

Iron-rich foods include dried beans (cooked garbanzos, kidney, soybean (tofu), lentils), shellfish-fish (clams, oysters, scallops, shrimp, tuna, sardines, mackerel), nuts (and peanut butter), organ foods (especially liver), meats (lean beef, chicken, turkey) and leafy green vegetables (spinach, broccoli, brussels sprouts, lettuce).

What precautions should I take after donating blood?

The last time I gave blood at a De Anza College blood drive, through Blood Centers of the Pacific, the handout they gave us said, in part:

“After donating, please:

…. Do not lift or carry heavy objects today. Do not do strenuous exercise today… Drink extra liquids the rest of the day. Eat a hearty meal within 4 hours.”

The last time I gave blood at a Red Cross Blood Services Center, the handout to take home said, in part:

“Be sure to take the following precautions:

Drink an extra four glasses (8 ounces each) of non-alcoholic liquids…Because you could experience dizziness or loss of strength, use caution if you plan to do anything that could put you or others at risk of harm. For any hazardous occupation or hobby, follow applicable safety recommendations regarding your return to these activities following a blood donation.”

Any donation facility will give you a personal number to identify your donation. If you remember important health information that you may have not given, or if you get sick or otherwise decide your blood may not be safe to give to another person, you can call the toll free number on the info page they will give you.

A British website warned:

“•People who smoke soon after giving blood are more likely to feel the effects of nicotine and therefore faint.

•People who take alcohol within a few hours of giving blood are more likely to feel faint because alcohol dilates the blood vessels. This causes less blood to be available to circulate to the brain leading to dizziness and fainting.

•Being in a hot room also causes the blood vessels to dilate and thus has a similar effect to alcohol.

•Rushing about, or vigorous exercise can also produce similar effects.

•Missing meals and not replacing fluids means a delay in the recovery from blood donation.

•Standing still for long periods of time can lead to pooling of blood in the legs, a situation similar to soldiers on parade. This reduces the amount of blood available to the brain.

If you rush about, miss a meal, have a ‘liquid lunch’, a cigarette, or get overheated you may feel faint even if you gave blood several hours ago.”

Aren’t there lots of people who give blood?

As of a 2007 study in TRANSFUSION, only 37 percent of the people in the United States are eligible to donate blood.

Previous studies show that only about 5% of eligible healthy donors give blood each year. Sometimes we have shortages regularly in many areas of the U.S. I get phone calls from the local blood bank asking me to donate again because they are sometimes down to a half day blood supply.


If every donor gave only one more time yearly,

we would not have blood supply problems.


Type O is the most in demand (about 60% of transfusions).. Because about 57 percent of the Latino population is type O, 51 percent of African Americans and only 45% of white Caucasians, it is critical that Latino and African American donors give regularly.

Is it true I can eat chocolate chip cookies after donating blood?

The Red Cross on North First Street in San Jose, California (which is certainly on some kind of a work or shopping commute my students take), has a huge supply of OJ, lemonade, chocolate chip cookies (and new & old magazines if you forget to bring some homework or want to catch up on your less important, unimportant or even trashy reading).

How often can I donate blood?

If you don’t change your life in a way that could prevent you from donating, you can safely donate every eight weeks.

How do I make an appointment to give blood?

call the American Red Cross at:
1-800-GIVE-LIFE (1-800-448-3543)

or contact:

Who gets blood donations?

Every three seconds, someone needs blood. People donate a unit of blood, about a pint. Usually each unit of whole blood is separated into various components, such as red blood cells, plasma, platelets, and cryoprecipitated AHF (antihemophilic factor). Each component generally is given to a different person according to their needs.

Needs include:

Accident Victim needs 4-40 units of red blood cells

Aneurysm needs 4-6 units of red blood cells

Bone Marrow Transplant needs 1-2 units of red blood cells every other day for 4 weeks; 1 unit of platelets daily for 4-6 weeks

Cancer Treatment needs 2-6 units of red blood cells; 1 unit of platelets daily for 2-4 weeks

Heart Transplant needs 4-6 units of red blood cells

Kidney Transplant needs 2 units of red blood cells

Knee Replacement needs 2 units of red blood cells

Liver Transplant needs 10 units of red blood cells; 2 units of platelets; 20 units of plasma

Premature Baby needs 1-4 units of red blood cells

Prostate Cancer needs 2-4 units of red blood cells

Another source said in a car accident up to 50 units of blood; bone marrow transplant 20 units of blood, 120 units of plasma; organ transplant 40 units of blood, 30 units of platelets, 25 units of plasma; burns 6 units of platelets; heart surgery 6 units of blood. It is not unusual for young leukemia patients to need eight units of blood a week.

Red blood cells have a 42-day shelf life and platelets only 5 days,
so the supply must be constantly replaced.

From a Red Cross leaflet:

“As soon as 24 hours after donating, your blood could be helping patients. Your blood’s plasma might be saving a young hemophiliac, your platelets might be helping a cancer patient, while your white blood cells might be helping a newborn fight a serious infection.”

More than 75 percent of Americans reaching age 72 will require a blood transfusion sometime in their lifetimes.
More than 95 percent of Americans will have a relative or friend who will need blood.

Is it true that donating blood can make me healthier?

An article at A Second Opinion Medical said, in part

“We all know giving blood helps others, but did you know donating blood is also a healthy habit for yourself?

Before donating blood, everyone must pass a mini-physical and a medical history examination. During the physical, your blood pressure, pulse, temperature and your hematocrit level (the level of red cells in your blood) are checked. Sometimes physical problems such as high blood pressure are found during a blood donation mini-physical. So donating blood can be a way to keep a check on your own health while helping others.

Preliminary studies also found that heart attacks and other cardiac problems were less common in men who had donated blood compared to men who had not. The two studies involved over 6,500 men and were conducted by the University of Kansas and the University of Kuopio in Finland. Researchers believe by giving blood, men — and post-menopausal women — rid their bodies of excessive iron, which is thought to contribute to heart disease.
While the medical community is still not certain if a link exists between blood donation and reduced risk of heart attack, giving blood certainly doesn’t harm a donor and helps patients who need blood.”

From Science Daily:

Men Who Donate Blood May Reduce Risk Of Heart Disease, According To KU Medical Center Study

Story by Rosemary Hope

“KANSAS CITY, Kan. – Men who donate blood may reduce their risk of heart disease by up to 30 percent, according to a study led by David Meyers, M.D., professor of internal medicine and preventive medicine at the University of Kansas Medical Center.

The study, “Possible association of a reduction in vascular events with blood donation,” is published in the August issue of the journal Heart.

The study supports the “iron hypothesis” which suggests that women are protected from atherosclerosis, or hardening of the arteries, because they have lower body stores of iron than men. Through menstrual blood loss, women have one-half the iron stores and suffer about one-half the heart attacks and deaths from heart disease as men of similar age.

“What this means for men is – if you donate blood, in a sense you can become a virtual woman and protect yourself from heart disease,” said Meyers. “We have identified another reason for blood donation, beyond altruism, for men.”

read the whole article at:

Perhaps also of interest:

Facts and Fallacies about first aid

Details about the De Anza College Red Cross first aid class.

How to call 911