Houston Methodist. Leading Medicine.
Houston Methodist. Leading Medicine

Frequently Asked Questions

Frequently Asked Questions

Q: I'm using high blood pressure medication. Can I donate blood?

A: Yes, you can donate as long as your blood pressure is within normal limits.

Q: Can I donate if I'm a diabetic?

A: Yes, you can donate as long as you don't have any signs or symptoms of peripheral vascular disease.

Q: Will my blood be tested for HIV and if so, will I be notified of the result?

A: Every unit of blood is tested for HIV. We test for the antibodies to the virus as well as the P24 antigen, which makes up part of the virus itself. You will be notified only if the test result is abnormal.

Q: This is my first donation. Should I expect to feel lightheaded?

A: No, the amount of blood that is removed at the time of phlebotomy is never enough to cause anyone to feel lightheaded. On rare occasions there are some donors who experience feeling of lightheadedness and dizziness, but it is not related to the amount of blood that we take out. It is probably more related to the anxiety that people feel when they are coming to donate.

Q: Does it hurt to donate blood?

A: Almost everybody says that the worst part about donating blood is the little finger stick that we do. The actual process of donating blood is much less traumatic than anybody can imagine and if you can stand to have your finger pricked, you can stand to donate blood.

Q: How long will it take before my body restores all the blood cells given during the whole blood donation?

A: Red cells last for approximately 120 days, however, your body has many reserve red cells and also has the ability to make more red cells when it needs to. Generally speaking in about four to six weeks your body should replace all the red cells that you give during a whole blood donation.

Q: Can I go exercise after I donate?

A: Yes, you can. There are a couple of things that you need to be careful about. The arm that the blood was taken from should not be used for any strenuous activity. This may cause the arm to bruise or to bleed and that can be painful. Also you may notice that your stamina after donating blood is less than it was before. If you for instance run one mile every day, the day that you donate you probably will be able to complete the mile but it will be much more difficult for you than it normally is.

Q: I have a pilot's license. Can I fly a plane immediately after a blood donation?

A: The FDA and the AABB both recommend that no one attempt to operate any heavy machinery that can be potentially dangerous within 48 to 72 hours after they donate. This is probably a good rule of thumb to follow. If you are going to do anything that is potentially risky or dangerous after you donate, you should wait two to three days before you attempt the activity.

Q: I got flu shot yesterday. Can I donate blood?

A: Yes, you can donate after you've got a typical flu shot. Vaccines are of three different kinds. There are vaccines that use a killed virus, there are vaccines that use an attenuated virus and there are vaccines that don't use any particles from the virus at all. The killed virus vaccines and the vaccines that don't use any particles from the virus are safe from blood donation standpoint. You can donate immediately after you get the vaccination. The vaccines that involve an attenuated virus, which means the virus is still alive but it shouldn't cause a disease, require that you wait full two weeks before you donate a unit of blood.

Q: How long can you store blood?

A: We can store blood for forty-two days if we don't freeze it. If we freeze it, we are allowed to store it for ten years, but freezing blood is a very poor way of storing blood. When you need blood right away, it takes at least two hours to thaw that unit and only about 80 % of the blood is usable. For these reasons we don't freeze units of blood unless there is some special need for it. Generally speaking we store blood in the refrigerator and we can store it for up to 42 days.

Q: What is the rarest blood type and what is the "universal donor?"

A: AB negative is the rarest blood type. The most common blood type is O positive. O negative is the universal donor of red cell. For plasma products, AB negative is the universal donor.

Q: Can I get sick because of blood donation?

A: No, you can't get sick because of blood donation in itself. Now, if you get up too fast after donation and you pass out and injure yourself, that's the kind of "sick" you can get after blood donation. This is the reason why we have people sit for a few minutes and drink some juice and have some cookies and generally just chat with us just for a while so we can make sure that this is an unlikely possibility when they walk out of here. As far as getting sick as a flu or cold after blood donation -- no that doesn't happen.

Q: I heard about the development of artificial blood. Does it mean that volunteer blood donors will no longer be needed?

A: Artificial blood is many years off in the future. The artificial blood that you hear about being produced today does have some uses, but these are fairly limited and restricted. They do not function nearly as well as human blood functions. Nature has developed an exquisite and complex system that we can't duplicate with our present technology. Artificial blood can only perform a few of the functions of red cells and they don't perform them very well.

Q: What are the "antibodies?"

A: There are two different kinds of antibodies. There are what we call "expected antibodies" -- this means for example that someone who is blood type "A" will have in their serum "anti B". The person who is type "B" will have in their serum "anti A". A person who is type "O" will have in their serum "anti A" and "anti B" and the person who is blood type "AB" will have neither "anti A" nor "anti B" in their serum. As a matter of fact when we do a blood type, we not only look into red cell to see whether they are type "A" type "B" type "AB" or type "O", but we also look at the serum for antibodies that we expect to be there. There are other red cell antigens though, that people can make antibodies to if they get exposed to those red cells. These antibodies are what we call "unexpected antibodies". We don't expect them to normally be present, but when people get transfused, when they have organ transplants or when women are pregnant, they get exposed to foreign tissues and they can make antibodies against these other red cells antigens. Therefore, when anybody gets transfused, we do what we call an antibody screen, which looks for these unexpected antibodies. If these unexpected antibodies are present then this patient has to get blood that lacks the antigens that triggered the creation of unexpected antibodies, to be sure that there is no transfusion reaction.

Q: Can I take some vitamins to build up my blood cells faster?

A: Anybody who donates a unit of blood and wants to replace that blood a little faster may do well to take a vitamin with iron supplement and they also want to make sure that they take vitamin C with it because that helps with the absorption of the iron. Other than that there is not much you can do to help yourself except to live a clean, healthy lifestyle. Make sure that your meals are nutritious and your body will take care of the rest.

Q: Will I lose weight?

A: Yes, you will lose a pound. I actually experimented on myself. I weighed myself before and after and you do lose about a pound when you donate, however, what you lose is a liquid and your body will very quickly replace that volume that you just lost. It will replace it when you have something to drink or something to eat and within a day, that pound that you lost will be back.

Q: I have tattoos and body piercing. Can I donate?

A: Because of the risk that tattoos and body piercing have, at least in terms of spreading hepatitis, we don't let people donate who have had tattoos and body piercing within the last year. There are donors who claim to have their ear pierced in a clean facility where they use sterile needles and the like. We do make exceptions for ear piercing, but only when that procedure was performed in the doctor's office. The reason for this is that we have a lot of confidence that a physician will know how to use sterile technique than other people would have. Generally speaking, if you have a tattoo or body piercing, you can't donate for a year following that incident.

Q: I'm taking antibiotics. Can I donate?

A: Most people think that the reason why they might not be able to donate is because of the medicines that they are taking and that those medicines themselves may have some harmful effect on the patients who would receive their blood. While that's true for a few medications, those are fairly rare. The reason why we ask about what medication you are taking is to get an idea about your general health. For instance, if you are taking antibiotics, the antibiotics themselves represent little or no risk to the patient if they got a unit of blood from you. The reason why you are taking those antibiotics is of more concern to us. If you have an infection that you are taking these antibiotics for, then you probably shouldn't be donating a unit of blood because that infection may find its way to that unit of blood. When we ask about medications we are actually asking about your general health. The medications that you taking are not necessarily of much risk but the condition that you donate with are of much greater concern to us.