What Is Hypothermia? Symptoms, Causes, and Prevention
Key takeaways:
Hypothermia is a dangerously low body temperature (less than 95°F) due to exposure to cold.
Hypothermia is a medical emergency. It's important to call 911 if you suspect someone has symptoms of hypothermia.
Someone’s age and living situation can increase the risk of hypothermia. Certain health conditions and medications can increase the risk too.
Table of contents
It doesn’t take prolonged exposure or extreme temperatures to cause a dangerously low body temperature, also called hypothermia. It can happen over a short period of time — and in temperatures that feel relatively mild.
So, as the temperature starts to drop in the winter, it’s important to know the early signs of hypothermia — and the things that put you at greater risk.
What causes hypothermia?
A normal core body temperature is around 98.6°F. Some people may run a little warmer or cooler. But hypothermia occurs when body temperature falls below 95°F.
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Hypothermia fits into two categories:
Acute hypothermia: This occurs after being exposed to cold for only a short time, like falling through ice into a frozen lake.
Chronic hypothermia: This occurs more slowly after prolonged exposure to cold temperatures. It can happen if you’re outside in the cold without enough layers for several hours. It can also happen inside at temperatures from 60°F to 65°F.
Why is hypothermia dangerous?
Hypothermia is a medical emergency. The body needs normal body temperature to work properly. When temperatures are too low, a lot goes wrong:
Circulation worsens, and organs don’t get enough blood or oxygen.
The heart can’t pump as well.
And the blood becomes more acidic, which affects the way most of the organs function. For example, it’s harder for blood to clot (stop bleeding).
The good news is that rewarming the body to normal temperatures can reverse these issues.
Common hypothermia symptoms
Early symptoms of hypothermia include:
Cold hands or feet
Puffy face
Dusky or paler-colored skin that’s cool to the touch; babies may look bright red (in lighter skin tones) or purple (in darker skin tones)
Shivering
Confusion
Drowsiness (especially in babies)
Fatigue
Slow or slurred speech
Do you always feel cold? It might be more than just your natural body temperature. Some medical conditions can make you always feel cold.
Running in cold weather: Follow these tips for staying warm and safe if you’re a cold-weather runner.
Can you get sick from being cold? Exposure to cooler temperatures can put you at risk for hypothermia. But it’s probably not going to give you a cold.
As hypothermia continues, everything starts to slow down. The body just isn’t warm enough to keep everything at a normal speed. Late symptoms of hypothermia include:
Slow movement, fumbling hands, or trouble walking
Slow, shallow breathing
Slow heartbeat, which can make it hard to detect a pulse
Severe confusion, which may worsen to the point of losing consciousness
How do you diagnose hypothermia?
Hypothermia is diagnosed when someone’s core body temperature is less than 95°F on a thermometer. But not everyone has a thermometer handy at all times. If you or others have symptoms of hypothermia, seek help.
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How do you treat hypothermia?
When you recognize the symptoms of hypothermia early, there’s a lot you can do to protect yourself and others from the more serious complications.
If you suspect someone has hypothermia, the first and most important thing to do is call 911. While waiting for help to arrive, you can also take the following steps:
Move the person to a warmer location (if possible).
Remove wet clothing, including socks and underwear.
Cover the person with warm and dry blankets.
Provide a warm beverage that doesn’t contain alcohol or caffeine (like hot water or herbal tea).
Some actions might seem like a good idea, but they can actually make the situation worse. If you’re worried about hypothermia, avoid:
Rubbing the person’s skin
Applying direct heat to the person (like placing them in a warm bath or using heating pads)
How do you prevent hypothermia?
There are a handful of ways you can help prevent hypothermia:
If you have a thermostat, keep it set to at least 68°F.
On cold days, wear multiple, loose layers — like a warm hat, scarf, and socks/slippers. This is true even if you’re staying inside. Remember to bundle up for bed too.
Wear a waterproof coat if it’s snowing or raining.
Change out of any damp clothes as soon as possible.
Avoid caffeinated beverages and alcohol, which can worsen heat loss.
In case of a power outage, stay with friends, family, or in an emergency shelter. It’s not safe to stay in a house without access to heat for long periods of time.
If you’re having trouble paying heating bills, some simple changes around the home can help cut costs. There are also resources to assist with bill payment. And if you need more layers, consider free clothing closets run by local charities or nonprofit organizations.
What increases the risk of hypothermia? [
Many things increase the risk of chronic hypothermia, even when temperatures aren’t that cold. It’s important to know the risk factors so you can help prevent it from happening.
Age and living situation
Age and living situations can increase the risk of hypothermia. Examples include:
Older age: This is especially true for those who live alone.
Babies and young children: This is because they can’t regulate their body temperature as well, and they can have trouble communicating that they’re cold.
People who stay outside for long periods of time: Examples include people experiencing homelessness and hikers.
Health conditions
Certain health conditions also increase the risk of hypothermia. These conditions can affect:
Circulation
The ability of the body to maintain a normal temperature
A person’s ability to dress warmly or get to a warm space
Here are some health conditions that can increase your chances of getting hypothermia:
Memory loss and dementia: People with trouble remembering things may not be oriented to the season or weather outside, forget to wear enough layers, or know how to get back to a warm place.
Conditions that affect movement: Examples include arthritis or Parkinson’s disease, which make it harder to put on warm clothes or move to a warm place.
Conditions that cause poor circulation: Examples include diabetes and peripheral vascular disease.
Low body weight: People with less body fat lose heat more easily.
Conditions that affect the brain or metabolism: This makes it harder to keep body temperature in the normal range.
Skin conditions: Conditions like burns make it easier to lose heat.
Spinal cord injuries: This can decrease circulation and make it easier to lose heat.
Severe mental health conditions: Conditions like schizophrenia might make it harder for someone to realize they’ve been cold for too long.
Substance use disorders: Drugs and alcohol can make it harder for someone to realize they’ve been exposed to cold for too long.
Medications
Certain medications can also increase the risk of hypothermia. Some medications make it harder for the body to maintain normal temperature. Others may decrease awareness of the cold or affect someone’s thinking. Examples include:
Medications for mental health conditions (like antipsychotics)
Opioid pain medications
Some blood pressure medications (like clonidine)
Frequently asked questions
The severity of hypothermia is sometimes described in three stages:
Mild hypothermia (90°F to 95°F): Someone is typically awake but shivering. They may have a hard time taking care of themselves.
Moderate hypothermia (82°F to 90°F): Someone has a noticeably altered level of consciousness. They may or may not be shivering.
Severe hypothermia (<82°F): Someone is completely unconscious and not shivering.
It's important to note that these temperature cutoffs and symptoms vary from person to person. They’re not hard and fast rules.
Acute hypothermia (like falling into a frozen lake) can occur within minutes. Chronic hypothermia can occur over the course of several hours.
If someone is experiencing any degree of hypothermia, they should be treated by emergency medical personnel. Even mild hypothermia shouldn’t be treated at home. It may be difficult to tell exactly how severe someone’s hypothermia is based on their symptoms or measured temperature. Healthcare professionals are also trained in knowing the fastest and safest rewarming techniques to help prevent any complications.
The bottom line
Hypothermia is a medical emergency and can be fatal. But it’s preventable and treatable, especially if recognized early. If you’re concerned someone has hypothermia, call 911. And if you’re having trouble keeping your home warm, it’s important to ask for help. There are assistance programs that can help with heating costs or clothing.
Why trust our experts?
References
Centers for Disease Control. (2024). Preventing hypothermia.
Dow, J., et al. (2019). Wilderness Medical Society clinical practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia: 2019 update. Wilderness and Environmental Medicine.
Duong, H., et al. (2024). Hypothermia. StatPearls.
Haverkamp, F. J. C., et al. (2018). The prehospital management of hypothermia - an up-to-date overview. Injury.
National Institute on Aging. (2024). Cold weather safety for older adults. National Institutes of Health.
Peiris, A. N., et al. (2018). Hypothermia. JAMA.
