Signs and Symptoms of Hypothermia

Medically reviewed by Mary Josephine Hessert, DO

Hypothermia is an abnormal drop in body temperature. Body temperature is typically around 98.6 degrees Fahrenheit; hypothermia is considered a body temperature below 95 degrees Fahrenheit.

Hypothermia occurs when the body loses heat faster than it can absorb or generate heat, making your body unable to regulate body temperature.

Hypothermia is usually caused by spending too much time in frigid temperatures. You can even develop hypothermia by getting chilled from rain or sweat in cooler temperatures above 40 degrees Fahrenheit. While not as common, hypothermia can also be caused by medications or an underlying health issue like an infection, low blood sugar (hypoglycemia), underactive thyroid (hypothyroidism), or adrenal insufficiency. 

The symptoms you experience depend on how severe your hypothermia is. As your body temperature drops, symptoms can progress from shivering and fatigue to severe confusion and even death.

Early Symptoms

Hypothermia symptoms can develop when your core body temperature drops below 95 degrees Fahrenheit. When your body temperature dips below that threshold and anywhere down to 89.6 degrees Fahrenheit, it is considered mild hypothermia. 

During this early stage, the body attempts to warm itself back up by shivering, an action that produces heat.

Your body might also try to preserve heat by reducing blood flow to the skin so that the blood instead flows to the internal organs to keep those warm. As your kidneys try to get rid of fluid to reduce blood pressure this blood flow change may cause, you might have an increase in urination.

Besides shivering and increased urination, other symptoms of mild hypothermia can include:

• Chattering teeth

• Fatigue

• Hunger

• Pale, dry skin

• Increased blood pressure

• Confusion

• Disorientation

• Lack of coordination

• Slow reaction time

The effects the cold temperature can have on your brain is what makes hypothermia especially dangerous even in its early stage. Because hypothermia can negatively affect your cognitive abilities and judgment, you might not realize you are experiencing hypothermia and so take no actions to reverse it.

Progressive Symptoms

Having a core body temperature between 82.4-89.6 degrees Fahrenheit is when moderate hypothermia symptoms can kick in. At this point, your heart, respiratory system, and metabolism (the body's energy processes) work overtime to keep your body functioning despite the cold temperature.

Eventually, the heat loss is just too much for your body. As a result, you'll stop shivering and start showing further cognitive decline. Other moderate symptoms of hypothermia include:

• Less dilated pupils

• Increased confusion and disorientation

• Loss of normal muscle reflexes (hyporeflexia)

• Extremely low energy (lethargy)

• Sleepiness

• Low blood pressure

• Shallow breathing

• Abnormally slow breathing

• Decreased heart rate

• Irregular heartbeat (arrhythmia)

Moderate hypothermia is also when people can start paradoxical undressing. This phenomenon causes people who are exposed to extreme cold to start undressing. When people are paradoxically undressing, they are so disoriented that they are unaware they're cold.

Late-Stage Symptoms

Severe hypothermia symptoms occur when core body temperature is below 82.4 degrees Fahrenheit. There have been hypothermia cases where body temperature drop as low as 57.2 degrees Fahrenheit.

At this stage, the body is completely overwhelmed by cold exposure. Disorientation, lethargy, and loss of muscle function are at an all-time high. Without proper temperature regulation, organ systems like the heart, brain, liver, kidneys, and muscles start shutting down. This can ultimately lead to death.

Late-stage hypothermia symptoms can include:

• No shivering

• Blue skin

• Dilated pupils

• Frequent urination

• Muscle injury or loss of muscle control

• Slowed pulse

• Irregular heartbeat

• Slowed or difficulty breathing

• Loss of consciousness

• Paradoxical undressing

• Coma

• Death

Symptoms in Children

Young children and infants are at an increased risk for developing hypothermia. This is because their bodies can't conserve heat the same as adults, and they often can't tell you if they feel too cold. Newborns are especially at risk for hypothermia because they cannot shiver and lose heat rapidly.  

Infants can develop hypothermia even from sleeping in a room that is too cold. Signs of hypothermia in infants include:

• Skin that feels cold

• Bright red skin

• Lack of energy or lethargy

When To Contact a Healthcare Provider

You must seek emergency care if you or someone you are with has any signs or symptoms of hypothermia. It is always a medical emergency once your temperature drops below 95 degrees Fahrenheit, so you should get care regardless of how severe the hypothermia is. Even mild hypothermia symptoms like shivering and confusion can progress to severe symptoms or death if left untreated. 

As you are taking someone to get emergency care or waiting for an ambulance, try to keep the person with hypothermia symptoms as warm as possible by removing any wet clothing and putting on dry clothes and layers of blankets. Giving warm, non-alcoholic drinks to a conscious person showing signs of hypothermia can also help increase body temperature. 

Once at the hospital, the person with hypothermia will likely be assessed for any complications the low body temperature might have caused. One condition that occurs alongside hypothermia is frostbite, an injury to the skin and underlying tissue from freezing. Other complications of hypothermia might include loss of muscle control in the arms and legs (ataxia) and inflammation of the pancreas (pancreatitis).

Questions To Ask Your Provider

You must seek emergency care if you have any symptoms of hypothermia. When you see your healthcare provider, consider asking them the following questions:

• How can I prevent hypothermia when I'm in the cold?

• How much time can I safely spend in cold weather?

• What outdoor temperatures and conditions increase my risk of hypothermia?

• Will I have any complications from hypothermia?

• Are any of my medications putting me at risk for hypothermia?

A Quick Review

Hypothermia symptoms can progress from mild to moderate to severe. In the beginning, your body will likely shiver in an attempt to keep warm. As your body temperature continues to drop, you'll probably stop shivering and feel even more disoriented. Once the loss of heat overwhelms the body, organ systems can shut down. Eventually, hypothermia can lead to death. Even early symptoms of hypothermia warrant immediate medical treatment since, if left untreated, your core body temperature can continue dropping to more dangerously low levels.

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