Why Do We Shiver When It's Cold?
Your muscles tighten and relax quickly, producing heat to warm you from the inside.When you feel cold, your body shivers because your muscles quickly contract and relax over and over. This makes heat to warm you up. Shivering can also happen at the start of an infection, often with a fever, and can be an early sign of hypothermia.
Shivering Makes Heat
When you feel cold, muscles throughout your body tighten and relax quickly, without your control. These tiny movements produce heat and help warm the body. This kind of shivering is also called chills.
Also at the Start of an Infection
Shivering doesn't only happen in a cold environment. It can also appear at the start of an infection, often along with a fever. Chills may come before a fever or before your core body temperature rises. Young children tend to develop higher fevers than adults and often have chills. Infants usually do not show obvious shivering.
Different from Goose Bumps
Goose bumps are not the same as shivering. Goose bumps happen in cold air or from strong emotions such as shock or fear. They make body hair stand up, forming a layer of insulation to help keep heat in. When you shiver, you may or may not have goose bumps.
Warning Sign of Hypothermia
If cold continues, your body can lose too much heat and develop hypothermia. Hypothermia occurs when the core body temperature drops below 95°F (about 35°C). Early signs include shivering, cold hands and feet, a puffy or swollen face, pale skin, slowed or slurred speech, and feeling sleepy, angry, or confused. Hypothermia affects the brain and makes it hard to think clearly, so a person may not realize they need help. If someone shows signs of hypothermia, call 911 right away, as it is a medical emergency.
Want to know more?
- Hypothermia can happen at cool temperatures above 40°F (about 4°C) if you become chilled from rain, sweat, or being in cold water.
- Wearing warm, loose layers helps keep you warm because air between the layers acts as insulation.
- The National Institute on Aging recommends keeping your home at least 68°F (about 20°C) in cold weather.
Quick quiz: test yourself
When you shiver in the cold, what is happening inside your body?
Show the answer
- Muscles rapidly tighten and relax to make heat
- Goose bumps trap warm air in body hair
- The body sweats to lower its temperature
Muscles rapidly tighten and relax to make heat Shivering happens when muscles quickly tighten and relax, producing heat to warm the body. Goose bumps help insulation but are not shivering, and sweating is for cooling down.
Shivering happens when muscles quickly tighten and relax, producing heat to warm the body. Goose bumps help insulation but are not shivering, and sweating is for cooling down.
Next quiz ›Sources
- Chills: MedlinePlus Medical EncyclopediaMedlinePlus（米国国立医学図書館）
- Cold Weather Safety for Older AdultsNational Institute on Aging（米国国立衛生研究所）
This article was written after checking the sources above as of 2026-10-03. Explanations may change as research progresses. Photo credits are shown below each photo.
