Can Your Blood Freeze? The Truth About Hypothermia

Can your blood freeze? It’s a question that sounds like it could be lifted straight out of a science fiction movie. The idea of a human body experiencing such extreme temperatures that the very blood coursing through its veins could become a solid block is, without a doubt, a deeply eerie thought. But, as it turns out, the question isn’t quite as fantastical as it might sound. While certainly not a common occurrence, it is entirely possible for a person’s blood to freeze under the right circumstances.

Of course, for most people, the idea of their blood literally turning to ice is more of a hypothetical concern than anything else. In their daily lives, the biggest threats to their blood are more likely to come from things like chronic illnesses and stress. But that doesn’t mean that the possibility of blood freezing shouldn’t be given some thought. After all, understanding how the body functions and reacts to extreme temperatures is crucial to a wide range of research and scientific fields.

So just how does blood freeze, and what implications could that have for the human body? These are the sorts of questions that scientists and medical professionals have been exploring for centuries. And while we may be no closer to discovering a solution to this theoretical problem, the act of exploring it in and of itself can be a fascinating glimpse into the inner workings of the human body. So let’s take a closer look at what causes blood to freeze, and what impact that can have on our health and well-being.

Can Blood Actually Freeze?

It is a common myth that blood freezes at a certain temperature, but the reality is a bit more complicated than that. While blood can solidify, it does not actually freeze in the way that water does.

  • Water freezes at 32°F (0°C)
  • Blood typically solidifies below 98.6°F (37°C)
  • Blood can become slushy or partially frozen, but it will not completely solidify due to the presence of various components such as proteins and salts.

To understand why blood doesn’t freeze in the same way as water, we have to look at its composition. Blood is made up of plasma, red and white blood cells, platelets, and various other components. When the temperature drops, the water in the blood can freeze, but the other components prevent it from turning solid.

In extremely cold temperatures, such as those found in the Arctic or at the summit of Mount Everest, blood can become slushy and lose its fluidity. This can cause issues with circulation and lead to frostbite or hypothermia.

What Temperature Does Blood Freeze At?

It is a common question whether blood can freeze inside the human body. The answer is, it can but under very specific circumstances.

  • Normal body temperature is around 98.6°F (37°C), which is well above the freezing point of water.
  • However, if a person is exposed to extremely low temperatures, such as those experienced in Antarctica, the temperature of their body can drop below 95°F (35°C).
  • At that point, the fluids in the body, including blood, can freeze.

What Happens When Blood Freezes?

When blood freezes, it can cause serious damage to the body’s tissues and organs. Ice crystals can form and puncture cells, and the thickened blood can obstruct blood vessels and restrict blood flow.

In scientific terms, the freezing point of blood is -1.6°C (29.12°F). This is slightly lower than the freezing point of water due to the presence of proteins and other substances in the blood.

Factors Affecting Blood Freezing

The following factors can affect the freezing point of blood:

  • Concentration of solutes in the blood, such as electrolytes and proteins.
  • pH level of the blood.
  • Pressure exerted on the blood.
  • Presence of anticoagulants or freezing point depressants.


While blood freezing is not a common occurrence, it can happen in extreme cold conditions. The freezing of blood can cause numerous health risks and damages to the body. Therefore, it is essential to take adequate precautions to prevent hypothermia and frostbite in extremely cold environments.

Temperature Freezing point
98.6°F (37°C) Above freezing point
95°F (35°C) Blood can start to freeze
-1.6°C (29.12°F) Freezing point of blood

Understanding the freezing point of blood is crucial for healthcare professionals and anyone who is planning to spend time in extreme cold climates.

How Does Low Temperature Affect Blood Viscosity?

When we think of low temperature, we often think of cold weather and freezing temperatures. However, cold temperatures can also have a significant effect on our bloodstream. When our bodies are exposed to low temperatures, our blood can experience changes in viscosity, or thickness. This can have various implications on our health.

  • Cold temperatures cause blood vessels to constrict, reducing blood flow and decreasing the amount of oxygen and nutrients that can reach body tissues.
  • As the viscosity of our blood increases due to cold temperatures, it becomes more difficult for our circulation system to pump the blood throughout the body.
  • At low temperatures, blood can also become more prone to clotting, which can increase the risk of heart attacks and strokes.

Research studies have shown that blood viscosity increases as soon as the body is exposed to low temperatures. A study by the University of Bialystok found that when human subjects were exposed to low temperatures (between 4°C and 16°C), their blood viscosity increased. Additionally, the study found that the warmer the body was, the lower the viscosity level was.

The table below provides an overview of the effects of low temperature on blood viscosity. As the temperature decreases, blood viscosity increases, making it harder for our bodies to pump blood, deliver nutrients, and fight infection.

Temperature (°C) Blood Viscosity
25 4.60
20 4.84
15 5.23
10 5.68
5 6.25
0 6.89

In conclusion, low temperatures have a significant impact on our blood viscosity. As the temperature drops, our blood becomes thicker and more difficult for our bodies to circulate. The changes in blood viscosity can lead to various health risks, so it is essential to stay warm and protect ourselves during low-temperature conditions.

Can blood freeze while still in your body?

The thought of one’s blood freezing inside their body is certainly terrifying. It is a common belief that blood can freeze while still circulating in one’s bloodstream, leading to organ failure and death. However, this is not entirely true.

  • While it is possible for blood to thicken and become slushy due to extremely low temperatures, it will not completely freeze in the human body. The reason being, our body temperature is set around 98.6°F (37°C), which is above the freezing point of water (32°F or 0°C).
  • Furthermore, the body has a natural mechanism to regulate its internal temperature, which prevents blood from freezing. The hypothalamus in our brain works like a thermostat, activating sweat glands or shivering muscles to maintain our body temperature within a narrow range.
  • It is worth noting that there are some medical conditions like cryofibrinogenemia or cryoglobulinemia that can cause blood to thicken and form clots, leading to adverse health effects. However, these are rare conditions.

Therefore, it is safe to say that the chances of blood freezing while still circulating in your body are close to nil. However, exposure to extreme cold without proper protection can cause hypothermia, which is a medical emergency that requires immediate attention.

It is crucial to take preventive measures like wearing warm clothing, drinking warm fluids, and avoiding extended exposure to freezing temperatures in case of exposure to extreme cold.

When individuals spend time out in freezing temperatures without the proper attire, their skin and outer layers of their body start to freeze. Frostbite conditions an area to freeze solid and causes permanent damage, which can lead to the need for amputation, not unlike what one may see in the movie 127 hours. Frozen feet result in amputation and death in the mountains more often than not.

Signs of hypothermia: Signs of frostbite:
Confusion and disorientation Skin that appears hard and waxy, with a white or grayish yellow hue
Slurred speech or mumbling Numbness in the affected area
Shallow breathing Tenderness or pain when pressed
Lack of coordination or clumsiness Blisters or swelling in the affected area

To conclude, blood does not freeze while circulating in the human body, thanks to the body’s internal temperature regulatory mechanism. However, exposure to extreme cold without proper protection can cause hypothermia and frostbite, which can lead to severe health complications and death. It is essential to take preventive measures and seek prompt medical attention in such cases.

What are the symptoms of hypothermia-induced blood freezing?

As hypothermia progresses and the body temperature drops further, blood can begin to freeze. This can cause a range of symptoms, including:

  • Loss of feeling in limbs: As blood freezes, it can impair nerve function, leading to numbness and tingling in the limbs.
  • Joint stiffness and pain: Blood freezing can also cause joints to become stiff and painful.
  • Difficulty moving: The loss of feeling and joint stiffness can make it difficult to move and perform tasks.
  • Slowed heart rate and breathing: As the body temperature drops, the heart rate and breathing can slow down significantly.
  • Confusion or disorientation: Hypothermia-induced blood freezing can also cause confusion, memory loss, and disorientation.

If left untreated, hypothermia-induced blood freezing can lead to more serious complications, including organ failure and even death. It is important to seek medical attention as soon as possible if you experience any of these symptoms.

In addition to the symptoms above, additional signs of hypothermia-induced blood freezing can be seen in a clinical setting. Table 1 below gives an overview of some of the laboratory values that might be affected:

Laboratory Value Normal Range Abnormal Range
Arterial blood gas pH: 7.35-7.45
PO2: 80-100 mmHg
PCO2: 35-45 mmHg
HCO3: 22-26 mEq/L
Complete blood count WBC: 4,500-11,000/mm3
RBC: 4.5-5.5 million/mm3
Hgb: 13-18 g/dL (males)
12-16 g/dL (females)
Hct: 38-52% (males)
34-47% (females)
Platelets: 150,000-450,000/mm3
Chemistry panel Sodium: 135-145 mEq/L
Potassium: 3.5-5.0 mEq/L
Chloride: 98-106 mEq/L
Bicarbonate: 22-28 mEq/L
BUN: 7-18 mg/dL
Creatinine: 0.6-1.2 mg/dL
Glucose: 70-100 mg/dL
Electrolyte imbalances
Renal dysfunction
Hypoglycemia or hyperglycemia

It’s worth noting that hypothermia-induced blood freezing is a rare occurrence and typically only seen in extreme cases. However, even milder cases of hypothermia can be dangerous and should be treated seriously.

What Happens to the Body When Blood Freezes?

Freezing blood is a rare phenomenon that occurs when the body is exposed to extremely cold temperatures for prolonged periods. When this happens, the water molecules in our blood start to expand as they freeze, putting pressure on our cells and tissues. Here are some of the things that happen to the body when blood freezes:

  • The cells in the body start to lose their function as they are deprived of oxygen and nutrients due to the congealed blood.
  • The organs like the brain and the heart may start to malfunction as the blood supply is disrupted.
  • The blood vessels may rupture due to the expansion of the frozen blood, causing internal bleeding and tissue damage.

These effects can be life-threatening and may lead to significant damage to the body if not addressed immediately. In severe cases, frozen blood can cause permanent tissue damage and organ failure.

How the Body Tries to Protect Itself

In order to protect itself from the dangers of freezing, the body has developed a range of adaptive mechanisms. When exposed to cold temperatures, the body responds by reducing blood flow to the extremities and diverting it to the vital organs like the brain and the heart. This helps to conserve heat and keep the organs functioning properly. The body also shivers, which generates heat by burning calories, and produces more urine to prevent water from freezing inside the bladder.

In addition, the body produces cryoprotectants, which are proteins and other molecules that help to prevent freezing damage by coating and protecting cells and tissues. This mechanism is used by some animals, such as frogs and turtles, which can survive freezing temperatures by producing high levels of cryoprotectants in their body fluids.

Preventing Freezing Injuries

To prevent freezing injuries, it is important to protect oneself from exposure to extremely cold temperatures. This can be done by wearing warm clothing, staying hydrated, and avoiding prolonged exposure to the cold. In case of emergency situations where exposure to cold is unavoidable, it is crucial to seek medical attention immediately to avoid permanent damage to the body.

Stage Symptoms Treatment
Frostnip Red, cold, and numb skin. Skin may be painful or itchy. Restoration of blood flow and rewarming of affected area.
Frostbite White, grayish-yellow, or bluish skin that feels cold and hard. Skin may eventually turn black and become numb. Immediate medical attention to prevent tissue damage and potential amputation of affected limb.
Hypothermia Shivering, confusion, slurred speech, drowsiness, and loss of coordination. Body temperature may be below 95°F (35°C). Gradual rewarming of the body, monitoring vital signs, and administration of warm fluids.

In conclusion, freezing blood can have severe consequences on the body and may cause permanent damage if not addressed properly. The body has developed mechanisms to protect itself from the dangers of freezing, but it is important to take precautions and seek medical attention in case of exposure to extremely cold temperatures to prevent freezing injuries.

Can blood be thawed after it has frozen?

Yes, blood can be thawed after it has frozen. Blood freezing usually happens during processes such as blood banking, transportation, and storage. Oftentimes, frozen blood is needed in emergency situations, and medical professionals need to quickly thaw the frozen blood to make it available for transfusion. However, special care must be taken during the thawing process to ensure the blood is safe to use.

  • There are two main methods used to thaw blood:
    • Refrigerator thawing: This is the preferred method of thawing blood. Blood is transferred from the freezer to a refrigerator and allowed to thaw slowly over a period of 6-24 hours depending on the volume of the blood product. It is important to note that once blood is thawed in the refrigerator, it must be transfused within 24 hours.
    • Water bath thawing: This method involves immersing the frozen blood in a warm water bath to thaw it quickly. This method is fast but risky, as it can lead to bacterial growth and hemolysis (destruction of red blood cells).

Regardless of the method used for thawing, blood thawing should be done in a controlled environment to minimize the risk of contamination and ensure the blood is transfused safely.

It is important to note that once blood has been thawed and is ready for transfusion, it must be used promptly; otherwise, it may deteriorate and become unsafe to use.

Frozen Blood Product Shelf Life After Thawing
Red blood cells 24 hours
Plasma 5 days
Cryoprecipitate 6 hours
Platelets 4 hours

Thawed blood has a shorter shelf life than fresh blood, and medical professionals must be aware of the expiration time to ensure they use the blood safely and effectively.

How does cryogenic freezing work and what happens to the blood during the process?

Cryogenic freezing, also known as cryopreservation, is a process of preserving biological matter at extremely low temperatures. The process involves cooling the biological material to temperatures below -130°C, which is cold enough to significantly slow down or completely stop all biological activity within the specimen. This process is commonly used in various fields, such as medical research, horticulture, and even in preserving the body or tissues of deceased individuals for future medical treatments.

But, what happens to the blood during the cryogenic freezing process? Below are some of the things that happen to blood when it is subjected to cryogenic freezing:

  • The blood is treated with a cryoprotectant that helps to protect the cells during the freezing process. Cryoprotectants are typically made up of substances such as glycerol or dimethyl sulfoxide (DMSO), which help to prevent cells from rupturing due to ice crystal formation during the freezing process.
  • Once the blood is treated with the cryoprotectant, it is cooled gradually to temperatures as low as -196°C. This slow cooling process allows the cryoprotectant to penetrate the cells and protect them from damage during the final cooling stage.
  • The final cooling stage involves immersing the blood in liquid nitrogen, which is at a temperature of -196°C. This temperature is cold enough to effectively halt all biological processes within the blood, including decay and the growth of bacteria.

Overall, the cryogenic freezing process helps to preserve blood for future medical use, such as in transfusions for emergency purposes or in laboratory research. However, it must be noted that there are still some limitations to the cryogenic freezing process, such as the potential for ice crystal formation within the specimen during the cooling process, which can damage the cells.

It is also important to note that the cryogenic freezing process is not the same as freezing blood outdoors in extremely cold temperatures, which can cause the blood to freeze and eventually lead to the formation of ice crystals that can damage the cells. The use of cryoprotectants and the gradual cooling process used in cryogenic freezing help to prevent this type of damage from occurring within the blood.


The cryogenic freezing process is a highly effective way of preserving biological material, including blood, for future use. The use of cryoprotectants and the gradual cooling process helps to protect the cells from damage during the final cooling stage, which involves immersing the blood in liquid nitrogen at -196°C. While there are some limitations to the cryogenic freezing process, such as the potential for ice crystal formation, it is still an important tool in medical research and emergency medicine.

Pros Cons
Preserves biological material for future use. The potential for ice crystal formation during the cooling process, which can damage cells.
The use of cryoprotectants helps to prevent cell damage during the cooling process. Some biological material may not survive the cryogenic freezing process.
Cryogenic freezing is useful in various fields, such as medical research and emergency medicine. Requires specialized equipment and expertise to perform successfully.

Overall, the benefits of cryogenic freezing are clear, and the process is likely to become even more important in the years to come as medical technology continues to advance.

Are there any medical treatments that involve freezing blood?

While the idea of blood freezing in the body may seem alarming, medical treatments that involve freezing blood have been used for a variety of purposes. Here are some of the ways blood freezing is used in medicine:

  • Cryoprecipitate therapy: Cryoprecipitate therapy involves using frozen blood products to treat bleeding disorders. Specifically, cryoprecipitate contains concentrated amounts of clotting factors and is used to treat disorders like hemophilia, von Willebrand disease, and fibrinogen deficiency. Cryoprecipitate can be thawed and administered as needed.
  • Cryosurgery: Also known as cryotherapy, cryosurgery uses extreme cold to destroy abnormal tissues, like tumors. During cryosurgery, a small probe is inserted into the affected area and liquid nitrogen or argon gas is used to freeze the abnormal tissue, which can then be removed. Blood loss may occur during this type of surgery and blood transfusions may be necessary.
  • Cryopreservation: Cryopreservation is the process of freezing and storing biological samples for later use. This can include blood, stem cells, and organs. Cryopreservation is used for both medical and research purposes.

In addition to these medical treatments, there are also experimental technologies that involve freezing blood. For example, researchers are exploring the use of cryogenic storage for blood transfusions in emergency situations, where quick access to blood products could be critical.

It’s important to note that while freezing blood can have important medical uses, it is not recommended to intentionally freeze blood within the body. Freezing can cause damage to red blood cells and other components of blood, which can lead to serious health complications.

Can prolonged exposure to low temperatures cause permanent damage to the blood?

Prolonged exposure to low temperatures can have a significant impact on the human body, including the blood. When exposed to cold temperatures, the body’s natural response is to vasoconstrict, or narrow blood vessels, in an effort to conserve heat and keep the body core warm. This can lead to changes in blood flow dynamics and properties, potentially resulting in permanent damage if left untreated.

  • Acute Cold Exposure: Acute exposure to cold temperatures can cause the blood vessels to narrow rapidly, which can lead to decreased blood flow and a reduction in oxygen levels. This can lead to nerve and tissue damage if blood flow is not restored promptly.
  • Hypothermia: Hypothermia occurs when the body temperature drops below 95°F, which can be life-threatening. Prolonged exposure to cold temperatures can lead to hypothermia, which can cause a slowing down of metabolic processes, including the circulatory system. This can lead to changes in the blood’s viscosity and result in permanent damage to the blood vessels, leading to hypoxia and tissue death.
  • Frostbite: Frostbite occurs when the skin and underlying tissues freeze due to cold temperatures. The prolonged exposure to cold can lead to a breakdown in the integrity of the blood vessels, which can result in the formation of blood clots and subsequent tissue damage. This can also lead to increased levels of red blood cells in the blood, which can cause changes in blood viscosity and increase the risk of cardiovascular disease.

In addition to the risks presented by prolonged exposure to cold temperatures, some individuals are more susceptible to the effects of cold on the blood. Individuals who have pre-existing cardiovascular or peripheral vascular disease may be at higher risk of developing permanent blood damage due to cold exposure. In some cases, these conditions may be exacerbated by prolonged exposure to cold, leading to complications such as heart attacks, strokes, and blood clots.

It is important for individuals who work or spend significant amounts of time in cold environments to take precautions to protect themselves from the dangers of prolonged exposure to low temperatures. This may include wearing appropriate clothing and protective gear, taking breaks to warm up, and staying hydrated. If individuals notice any changes in their circulation or experience symptoms such as numbness or tingling, they should seek medical attention promptly to avoid potential permanent damage to their blood and overall health.

Complication Symptoms
Hypothermia Shivering, confusion, drowsiness, slowed heart rate
Frostbite Numbness, tingling, white or grayish-yellow skin, blistering
Peripheral vascular disease Leg pain or cramping, muscle weakness, changes in skin color

Overall, prolonged exposure to low temperatures can have significant effects on the blood, leading to permanent damage if left untreated. It is important for individuals to take precautions to protect themselves from the dangers of prolonged cold exposure and seek medical attention if they experience any changes in their circulation or symptoms related to hypothermia, frostbite, or peripheral vascular disease.

Can Your Blood Freeze FAQs

1. Can your blood actually freeze?

Yes, blood can freeze under certain conditions like extremely low temperatures.

2. At what temperature will your blood start to freeze?

The freezing point of blood is around -2°C or 28.4°F.

3. Is it possible for blood to freeze inside your body?

No, it is unlikely for blood to freeze inside your body as our internal body temperature remains around 37°C or 98.6°F.

4. What effects can freezing blood have on your body?

Freezing of blood can cause severe damage to blood vessels and cell membranes, leading to cell death or damage.

5. Can you survive if your blood freezes?

No, if your blood does freeze, it can cause serious health problems and can ultimately lead to death.

6. Is it safe to expose your skin to freezing temperatures?

No, exposure to extremely low temperatures can lead to frostbite, which can cause severe damage or loss of tissues.

7. How can one prevent their blood from freezing?

You can avoid exposure to extremely low temperatures, dress appropriately for cold weather and stay indoors during cold conditions.

Closing Thoughts

We hope this article helped you understand the effects of freezing blood and the precautions you can take to prevent it. It is important to keep yourself warm and protected during extremely cold weather conditions. Thanks for reading and don’t forget to check back for more informative articles!