Key takeaways:
Having low hemoglobin due to low iron levels is a common reason to get turned away from donating blood.
Some people may be able to boost their iron levels before donating blood. Eating iron-rich foods or taking iron supplements can help raise your iron level.
Talk with a medical professional if you have low hemoglobin or iron levels. This can be a sign of an underlying medical condition.
Close to 7 million people in the U.S. donate at least 1 unit of blood every year. And about 20% are turned away for various reasons.
In order to donate blood, potential donors have to meet certain requirements. One common reason for being turned down as a blood donor is low hemoglobin — commonly due to a low iron level.
This can come as a surprise, especially if you’ve been donating for years. But iron deficiency — with or without anemia — can happen for many reasons. And you may not have any symptoms.
Donating blood can cause iron deficiency or worsen it if you donate often. Let’s take a closer look at why your iron level is important when donating blood and how you can safely raise your iron level.
What are iron and hemoglobin?
Iron is an essential mineral found in nature. Your body can’t make its own iron. People get it by eating foods rich in iron.
Hemoglobin is a protein. If your body has enough iron and amino acids (protein building blocks), it can make all the hemoglobin it needs.
Iron and hemoglobin are assembled together and packed into red blood cells. Together, they carry oxygen and deliver it to all the tissues in the body.
How can you raise your iron levels for blood donation?
The most common ways to raise your iron are through the food you eat, iron supplements, and improving how much iron your body absorbs.
1. Eat iron-rich foods
Most people get enough iron from the food they eat. But if you’re looking for a boost in your iron before donating blood, focusing on iron-rich foods may help.
Iron in food may be bound to a protein called heme (one of the building blocks of red blood cells). This type of iron is easily absorbed, but it only makes up about 10% of iron in the diet. Iron may also be unbound (non-heme iron). This type of iron isn’t as easily absorbed and makes up most of the iron we get from food.
Some of the foods that are high in iron include:
Meats, poultry, and organ meats
Fish and shellfish
Fortified grains and cereals
Green, leafy vegetables
Beans and legumes
Sesame seeds and cashews
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2. Take iron supplements
Many regular blood donors can’t restore their iron levels just by eating iron-rich foods. But you may benefit from taking iron supplements. Iron can be found in many multivitamins or as a separate supplement.
Either way, you’ll want to aim for the recommended daily dose for you. This will usually be based on your age and if you have a monthly menstrual cycle. It's important to take the proper dose so you don’t take too much or too little iron.
3. Increase iron absorption
Increasing how much iron you’re absorbing through your diet can give you a boost before donating blood. One way to improve how much iron is absorbed through your gut is to consume vitamin C at the same time. Foods that have lots of vitamin C and can increase your iron absorption are:
Citrus
Strawberries
Tomatoes
Red bell peppers
Broccoli
When to seek medical advice
If your iron level is on the lower end of normal, you can try to raise it before donating. Keep in mind that the change isn’t immediate. It may take at least a couple of weeks to see a difference in your blood levels.
If your iron level doesn’t improve, it’s a good idea to check with your healthcare team. They can help you find out what’s going on, likely starting with certain blood tests.
Are there things you should avoid to help improve your iron levels?
Certain foods, beverages, and medications can decrease how much iron you absorb from your food. You may want to avoid or limit these for a short while when you’re preparing to donate blood or when taking iron supplements. Things that may decrease iron absorption include:
Coffee
Tea
Red wine
Chocolate
Foods high in calcium, like milk, cheese, and yogurt
If you’re taking an iron supplement, consider taking it at a different time than when you’re eating and drinking these items.
What are the iron and hemoglobin requirements for donating blood?
Blood banks don’t actually measure your iron level at the time of donation. Instead, they look at your hemoglobin level. Hemoglobin is easy to measure, and in some cases it can help to give a good estimate of whether you have enough iron.
The requirements for hemoglobin for blood donors are:
Male donors: more than 13 mg/dL
Female donors: more than 12.5 mg/dL
Maximum hemoglobin: 20 mg/dL
If your hemoglobin is lower than the minimum level, you’ll be able to try again in a few weeks.
Why can’t you donate blood if you have low iron?
A low level of iron means your body can’t make enough red blood cells to meet your body’s need for oxygen. Donating blood removes even more blood cells and causes your iron levels to drop even lower.
About 500 mL of blood is taken from your body when you donate blood. This is about 10% of the total amount of blood you have in your body. If you have a normal iron level when you donate, your body will be able to absorb more iron to replace what you lost. But if you’re already low, it’ll put extra strain on your body, making it more difficult to recover quickly.
Who is at risk for iron deficiency?
Causes of iron deficiency include:
Decreased iron absorption
Bleeding
Pregnancy
Inadequate iron intake
So anyone at risk for these causes may develop iron deficiency. Some examples include people who:
Follow a vegetarian diet
Donate blood frequently
Are menstruating
Have certain medical conditions (like heart failure and chronic kidney disease)
Have impaired absorption (like from celiac disease and inflammatory bowel disease)
Have a bleeding disorder (such as von Willebrand disease or hemophilia)
Use anti-inflammatory medications or heartburn medications long term
Frequently asked questions
There are at-home testing kits for purchase that use a blood drop from a finger prick. They may test for iron and/or ferritin, a protein that stores iron. It’s important to note that these tests are less accurate for diagnosing iron deficiency. So it’s a good idea to talk with a healthcare professional about your results.
Yes, researchers have noted a link between high iron and ferritin levels and higher levels of uric acid in the blood. Uric acid is what builds up in the joints, leading to gout flares. This relationship might be due to iron’s role in inflammation. But it’s also noteworthy that iron-rich foods are top triggers for gout flares.
There are at-home testing kits for purchase that use a blood drop from a finger prick. They may test for iron and/or ferritin, a protein that stores iron. It’s important to note that these tests are less accurate for diagnosing iron deficiency. So it’s a good idea to talk with a healthcare professional about your results.
Yes, researchers have noted a link between high iron and ferritin levels and higher levels of uric acid in the blood. Uric acid is what builds up in the joints, leading to gout flares. This relationship might be due to iron’s role in inflammation. But it’s also noteworthy that iron-rich foods are top triggers for gout flares.
The bottom line
People rely on donated blood every day. And millions of donors meet that need each year. But potential donors are turned away if they have low hemoglobin from low iron levels. There are easy ways to boost your iron level before donating blood. These include increasing the amount of iron-rich foods you eat, taking a supplement that contains iron, and boosting iron absorption with vitamin C. If you have a low iron or hemoglobin level that doesn’t respond to increased iron intake, talk with your healthcare team.
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References
America’s Blood Centers. (2022). U.S. blood donation statistics and public messaging guide.
American Red Cross. (n.d.). Blood supply statistics.
Association for the Advancement of Blood & Biotherapies. (n.d.). Hemoglobin screening/iron management.
Auerbach, M., et al. (2025). Iron deficiency in adults: A review. JAMA.
Fatima, T., et al. (2018). The relationship between ferritin and urate levels and risk of gout. Arthritis Research & Therapy.
Mantadakis, E., et al. (2022). Iron deficiency and blood donation: Links, risks and management. Journal of Blood Medicine.
Martinez, S. (2024). How much blood is taken when you donate? Oneblood.
National Institutes of Health, Office of Dietary Supplements. (2025). Iron: Fact sheet for health professionals.
Oneblood. (2019). Low iron & blood donations.
Piskin, E., et al. (2022). Iron absorption: Factors, limitations, and improvement methods. ACS Omega.
