Donating Blood

Medically Reviewed by Minesh Khatri, MD on August 31, 2022
5 min read

If you’ve decided to donate blood, you may be curious about what to expect. Giving blood is a simple, safe way to make a big difference in people’s lives. Knowing what will happen before, during, and after you donate can help you prepare for the process.

Every 2 seconds, someone in the United States needs blood. Donating blood can help:

  • People who go through disasters or emergency situations
  • People who lose blood during major surgeries
  • People who have lost blood because of a gastrointestinal bleed
  • Women who have serious complications during pregnancy or childbirth
  • People with cancer or severe anemia sometimes caused by thalassemia or sickle cell disease

There are also potential benefits for people who regularly donate blood:

  • Lower iron levels in blood. This is a plus if your iron levels are too high. Donating blood removes some red blood cells, which carry iron throughout your body.
  • Better cholesterol and triglyceride levels. In one study, researchers checked levels of total cholesterol, triglycerides, HDL (“good”) cholesterol, and LDL (“bad”) cholesterol in 52 people who regularly gave blood and 30 other people. Levels of triglycerides, total, and LDL cholesterol were all lower in those who regularly gave blood. It’s not clear why.
  • Emotional benefits from knowing you helped someone else, even if it’s a stranger. There may also be benefits from taking part in a blood drive with other people from teaming up to do good.

If you think you want to donate blood, it’s important to make sure you meet the requirements and that you properly prepare.

Requirements for blood donation. First, you’ll need to find a blood bank or blood drive and make an appointment. Be sure to ask about any specific requirements for donors and what kinds of identification you need to bring with you.

You’ll need to be:

  • At least 16 years old to donate whole blood (at least 17 to donate platelets) in most states
  • Weigh at least 110 pounds
  • In good health and feeling well

Your local blood bank may have more requirements, so check with them. When you call, tell the person on the phone if you have health concerns or problems or if you’ve recently traveled outside the country.

In the weeks before your appointment, you’ll want to make sure you’re getting a healthy amount of iron from food. Meat and seafood, as well as vegetables like spinach and sweet potatoes, are good sources of iron. Certain breads, fruits, and other foods like beans and tofu can be good options too.

The day of your appointment, prepare yourself by drinking plenty of fluids and wearing comfortable clothes with sleeves that you can easily roll up above your elbow. Make sure you have a list of all the prescription and over-the-counter medications you’re taking, as well as the proper forms of ID.

How often can you donate blood? If you donate whole blood, you need to wait 56 days between donations -- possibly longer, depending on the policy of your blood bank.

If you’re donating platelets, the American Red Cross allows people to do this every 3 days, up to 24 times in a year. Plasma can be donatd every 28 days.

The blood donation process can be broken down into four steps:

  1. Registration
  2. Medical history and mini-physical
  3. Donation
  4. Refreshments

While the whole process, from the time you get to the facility to the time you leave, can take about an hour, the actual donation itself may take as little as 8-10 minutes. If you donate platelets, a machine filters the platelets out of your blood and returns the rest of your blood to you. This process takes longer (2-3 hours).

1. Registration

When you arrive at the blood bank or blood drive, you’ll sign in for your appointment and show your ID. Then you’ll complete paperwork that includes general information like your name, address, and phone number.

2. Medical history and mini-physical

Before you donate, an employee from the blood bank will ask you some confidential questions about your health and lifestyle. You’ll also get a short health exam or “mini-physical.” An employee will take your pulse, blood pressure, and temperature, and take a small amount of blood for testing.

They’ll ask you about:

  • Your health history
  • Travel
  • Medications you take
  • Sexual activity (questions are about specific behaviors, not sexual orientation)

The questions are based on guidelines developed by the AABB (formerly called the American Association of Blood Banks) and approved by the FDA.

They’ll test your blood to see what blood type it is and to check for:

Tattoos, in most states, aren’t a barrier to giving blood, provided that the tattoo artist followed good safety practices (like using sterile needles and not reusing ink). A few states may require a waiting period between when you get a tattoo and when you donate blood, but in general, it’s not an issue.

3. Donation

When it’s time to donate, here’s what will happen:

  • You’ll go into a donor room where you’ll lie down on a cot.
  • A phlebotomist (an employee who draws blood) will clean your arm and insert a new, sterile needle into your vein. This takes just a few seconds, and it can feel like a quick pinch.
  • You’ll donate about 1 pint (one unit) of blood. The process should take less than 10 minutes. But if you’re donating platelets, red cells, or plasma by apheresis, the process can take much longer: up to 2 hours.
  • When you’re done, you’ll raise your donation arm and put a little bit of pressure on it, which helps your blood clot. Then they’ll put an adhesive strip on your arm.

4. Refreshments

After you’re finished, you’ll be given snacks and a drink to help your body get back to normal since you lost some fluids. You’ll want to sit and relax for at least 10 minutes to restore your strength and get some energy back before you leave.

There aren’t any lasting side effects, but you may temporarily:

  • Need to hydrate. Drink more non-alcoholic beverages for 24-48 hours after you donate blood.
  • Need to take it easy. Don’t work out or do any hard physical activity for 24 hours after giving blood.
  • Feel lightheaded. Lie down for a few minutes until you feel ready to get back up.
  • Have a little bit of bleeding from the spot where you donated. Raise your arm and apply pressure to that spot for a few minutes.
  • If you have bruising in that area, use an ice pack on it.