How Low Can Hemoglobin Go Before Death?
Written By Kobi Nathan, Pharm.D., M.Ed., CDP, BCGP, AGSF
Sleep Disorders
February 24, 2023

Updated May 20, 2023.

The medical problem anemia is caused by a low amount of hemoglobin or low red blood cell count in the body.

Anemia can be caused by many reasons. Here are some of them:

  • Injury or illness resulting in blood loss
  • Some forms of cancer
  • Changes in the body due to pregnancy or growth spurts during puberty
  • Iron deficiency
  • Problems with the liver
  • Chronic kidney disease (CKD)

A slightly low hemoglobin count isn’t always a cause for concern since some people have low hemoglobin counts for no reason.

But having too little hemoglobin can cause serious health problems, like heart problems or even death.

But how low does hemoglobin have to get before a person dies?

In this article, we’ll discuss:

  • What exactly is hemoglobin
  • Potential causes of low hemoglobin
  • Symptoms of low hemoglobin
  • How low can your hemoglobin go before it causes death
  • How to prevent and treat low hemoglobin before it is too late


What is Hemoglobin?


Hemoglobin is a protein found in red blood cells that contains an iron atom.

It binds oxygen molecules, enabling it to carry out its role of shuttling oxygen from the lungs and returning carbon dioxide back.

Hemoglobin consists of four protein molecules known as globin chains and one heme group, which contains the iron atom.

Hemoglobin’s four globin chains and heme group, with its iron atom, enable it to link up with oxygen molecules so they can be moved around the body.

Hemoglobin can carry oxygen from the lungs to other body parts and facilitates the removal of carbon dioxide through exhalation.

As hemoglobin moves through small capillaries in tissue, some of its oxygen binds with hydrogen to create water molecules that are then released into tissue spaces or returned back into circulation through veins and arteries.

In addition, when hemoglobin returns from tissues carrying carbon dioxide molecules instead of oxygen, it helps transport this waste product back out through exhalation so that our bodies can get rid of toxins more efficiently.

As stated in the introduction, anemia, blood loss, and nutritional deficiencies are some of the main factors that can lead to a decrease in hemoglobin levels.

Key Takeaway: Hemoglobin is a protein found in red blood cells that facilitates the transport of oxygen from the lungs to other parts of the body and carbon dioxide back to its point of origin. It acts like an express train between these two locations, delivering and picking up its passengers along its journey. When hemoglobin levels drop too low, the consequences can be disastrous, ultimately leading to death in patients.

What are normal hemoglobin levels?

The amount of oxygen that a person’s red blood cells can carry is shown by their hemoglobin count. The amount of hemoglobin in whole blood is measured in grams (gm) per deciliter (dL). One decilitre is equal to 100 milliliters.

From adolescence on, the normal range varies from person to person based on things like age and gender.

Men should have between 14 and 18 g/dl of hemoglobin, and women should have between 12 and 16 g/dl.

Most of the time, a person’s hemoglobin count is low if it’s below the normal range.

Is there a simple test for anemia?

Yes, there is! Usually, the complete blood count (CBC) test is used to measure the amount of hemoglobin in the blood.

CBC is a common test that your doctor may order to help find out what’s wrong with you, such as an infection, iron-deficiency anemia, or leukemia.

Causes of low hemoglobin levels

It is important to note that having a slightly low hemoglobin level (low Hb) is nothing to run to your doctor about. Many people have borderline low levels and lead perfectly fine daily lives.

However, the situation becomes dangerous when hemoglobin levels are severely low. There are many possible causes of a low hemoglobin count, leading to iron deficiency anemia. Here are some of them:

  • Major bodily changes such as pregnancy or puberty
  • A lot of blood loss due to injury, heavy menstrual flow, or traumatic accidents
  • Diet low in iron, Vitamin B12, and Folate (Vitamin B9)
  • Chronic blood loss due to stomach ulcers or colon cancer
  • Acute blood loss and anemia due to GI bleed caused by NSAID use
  • Certain medications (antiretrovirals, anticoagulants, Aricept, chemotherapy drugs, etc)
  • Sickle cell disease
  • Chronic kidney disease (CKD)
  • Blood and lymphatic system cancers (Leukemia, Lymphoma)

Symptoms of Low Hemoglobin Levels

If you have a low hemoglobin, your body cannot effectively move much-needed oxygen to all body tissues. It then makes sense that the following symptoms of iron deficiency anemia will result:

  • Fatigue and Weakness (tired easily)
  • Chest pain
  • Fast heartbeat (heart is trying to shuttle oxygen to tissues)
  • Pale or yellow skin, gums, and nails (due to lack of oxygenated blood)
  • Shortness of breath (due to lack of oxygen)
  • Dizziness or lightheadedness (brain is lacking oxygen)
  • Feet and hands are swollen or cold
  • Difficulty concentrating or completing everyday tasks


Symptoms of anemia can vary from moderate to serious and, if left untreated, may become life-threatening and cause death.

Realizing the risks associated with a very low hemoglobin count is critical to obtaining prompt treatment.

The video below from one of my favorite YouTube channels on medical topics discusses the signs and symptoms of Anemia. I highly recommend you check it out:

Can low hemoglobin cause death?

As we know, hemoglobin is needed for a person to stay alive. Without enough hemoglobin, the body can’t move oxygen from the lungs to the tissues and cells as well as it should. To compensate for the lack of oxygen, your heart pumps more blood.

Because low hemoglobin makes the heart work harder than usual, it can hurt the way the heart works by increasing the size of each stroke and putting stress on the heart through a higher heart rate.

A constant, sustained, fast heart rate can cause the heart to work too hard, which can cause problems like heart failure.

If not treated promptly and correctly, heart failure will be fatal.

Studies show that a severe lack of iron can hurt the left ventricle of the heart. This is called left ventricular (LV) dysfunction, which almost always leads to heart failure.

How low can hemoglobin go before it causes death?

According to the National Institutes of Health (NIH), a hemoglobin level drop of less than 6.5 g/dL is dangerous and could lead to death.

Hemoglobin levels vary between individuals and gender. To review, normal hemoglobin levels are as follows:

Women: 12-16 g/dL

Men: 14-18 g/dL

Treatment Options for Low Hemoglobin Levels:

Treatment options depend on the underlying cause of low hemoglobin but typically involve iron supplements, iron infusion, blood transfusions (in extreme, life-threatening cases), and medication prescribed by a doctor depending on the severity of symptoms. If the anemia is due to a GI bleed, your doctor will perform surgery to stop the bleeding.

In some cases, lifestyle changes such as increasing dietary iron intake may also help improve anemia symptoms.

Most of the time, reversing these underlying causes can restore hemoglobin to normal levels.


Key Takeaway: Hemoglobin levels that become too low can be extremely dangerous and even lead to death if not addressed quickly. Treatment options depend on the underlying cause but may involve iron supplements, blood transfusions, or medication prescribed by a doctor as well as lifestyle changes such as increasing dietary intake.

How to prevent low hemoglobin?

Being proactive and leading a healthy lifestyle with proper, nutritious food can help prevent your hemoglobin levels from getting dangerously low.

Eating more food rich in iron and folate can increase the production of red blood cells, in turn increasing hemoglobin levels. Sources of iron and folate include:

  • Leafy greens
  • Red meat
  • Liver and other organ meats
  • Fortified cereals (but choose non-sugary kind!)
  • Lettuce
  • Avocado
  • Beans, lentils, and other legumes
  • Peanuts
  • Baked potatoes


The short video below from the New York Blood Center describes some natural ways you can increase your hemoglobin:

FAQs in Relation to How Low Can Hemoglobin Go Before Death

How long can you survive with low hemoglobin?

The amount of time a person can survive with low hemoglobin depends on the severity of their condition and other factors such as age, overall health, and lifestyle.

Generally speaking, if left untreated or unmanaged for long periods of time, severe anemia due to low hemoglobin levels may be life-threatening.

Nevertheless, with appropriate changes to one’s lifestyle, like dietary adjustments and physical activity, many people can manage their symptoms.

Additionally, treatments like blood transfusions or iron supplements can help raise hemoglobin levels in some cases. For an individualized approach, consulting a physician is recommended.

What level of hemoglobin causes death?

A person’s hemoglobin levels must drop below 6.5 g/dL to be considered life-threatening, as this is the point at which oxygen-carrying capacity has been so severely diminished that vital organs and tissues can no longer function properly, leading to death.

Hemoglobin levels may vary due to age, gender, environment, or pre-existing medical issues.

What are normal hemoglobin levels for men and women?

For men, a normal hemoglobin level ranges between 14–18 g/dL. The normal range for women is between 12 and 16 g/dL.

How do you reverse low hemoglobin?

Low hemoglobin levels may be a sign of an underlying health issue. Anemia, chronic kidney disease, bleeding disorders, bone marrow failure, malnutrition, and certain cancers can all cause this problem.

Symptoms associated with low hemoglobin include fatigue and weakness due to decreased oxygen delivery to the body’s tissues.

Treatment depends on managing the underlying cause of the low hemoglobin level and may involve medications like iron supplements or blood transfusions in more severe cases.


Realizing the gravity of low hemoglobin levels is critical, as they can be hazardous and even fatal if neglected.

It is essential for individuals with low hemoglobin levels to seek medical attention as soon as possible to prevent any further complications or death.

In extreme cases, a person’s hemoglobin level may drop so low that it could lead to organ failure and ultimately result in death.

Fortunately, an individual diagnosed with anemia can reverse a hemoglobin drop by identifying and treating the underlying causes of the problem.


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