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What is the normal temperature of blood?

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Updated on December 10, 2020

In general, normal blood temperature is about the same as normal body temperature, or about 98.6℉ (37℃).

Blood outside of the body will remain the same temperature for only a few minutes. After a few hours, blood cells will die and the blood will reach room temperature.

As your body temperature changes, so does the temperature of your blood. In this article, we’ll explore how the body regulates its temperature and how blood plays a role in this process.

How does your body regulate temperature?

Your body’s temperature may change throughout the day based on what you’re doing — like exercising, sleeping, or eating.

If your body temperature gets too high or too low, a part of your brain called the hypothalamus uses a process known as thermoregulation to get your temperature back to normal.

Different mechanisms are used during thermoregulation, including vasodilation and vasoconstriction, sweating, and hormonal thermogenesis.

High body temperatures


If your body temperature reaches 100.4℉ (38℃) or higher, it’s considered a fever. This can happen as a reaction to:

  • Medications
  • Infections
  • Heart attacks or strokes
  • Heat strokes
  • Burns
  • Inflammation
  • Medical conditions including arthritis, hyperthyroidism, leukemia, and lung cancer

If you have a fever, your body will try to reduce your temperature through sweating or vasodilation. During vasodilation, your blood vessels grow larger to increase the blood flow through your body, which ultimately cools you down.

Mild fevers are usually treatable at home with fever reducers like ibuprofen or acetaminophen. In adults, high fevers above about 103°F (39.4°C) warrant a trip to the doctor.

Heat stroke

You may experience heat stroke if your body’s temperature is too high and you can’t regulate it. It usually results in rapid heart rate and hot skin. You may also lose consciousness.

Causes of heat stroke include:

  • Drinking alcohol
  • Dehydration
  • Wearing heavy clothing

Heat stroke can be very dangerous. If you think you might be experiencing heat stroke, seek immediate medical treatment.

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Low body temperatures

Low body temperatures are generally due to being in cold conditions. They may also be caused by:

  • Alcohol
  • Drug use
  • Shock
  • Diabetes
  • Hypothyroidism

To combat lower temperatures, your body uses vasoconstriction. During vasoconstriction, the blood vessels under your skin will shrink to decrease the blood flow to your skin. This will help you retain heat.

You may also begin shivering. Shivering is a muscular reaction that generates heat in an effort to warm you up.

You may not need to worry if low body temperature is your only symptom. You’ll probably warm back up once you’re able to get out of the cold. However, low body temperature can be a sign of something more serious if you’re experiencing it alongside other symptoms like:

  • Chills
  • Tremors
  • Confusion
  • Difficulty breathing

If that’s the case, it’s best to seek immediate medical attention.

The takeaway

Blood temperature is usually around 98.6℉ (37℃), which is the same temperature as your body normally is.

If you get too cold or too hot, thermoregulation helps bring your temperature back to normal. You may shiver or sweat, or your blood vessels may dilate or constrict.