Cooling a Burn: How Long, How Cold, and Why It Matters
Cool running water, for longer than most people think, and never ice or butter. Why cooling works, what to put on a burn afterwards, and which burns need 911.
Jarrett Chisholm, ACP · October 22, 2026 · clinically reviewed by Jarrett Chisholm, ACP
Where this is taught: Intermediate First Aid, Basic First Aid and Standard Child Care First Aid.
Most people know to put a burn under the tap. Very few leave it there long enough. A few seconds of cold water until it stops stinging, then a towel, is the usual approach, and it leaves most of the benefit behind.
Image needed · hero
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Kitchen sink, natural light. An adult forearm with a mild red mark (make-up) held under a gentle stream of cool tap water. On the counter beside the sink, a phone shows a countdown timer clearly reading around 18 minutes remaining. A watch and a ring sit on the counter, already taken off.
Alt text ready: “A forearm held under a running kitchen tap while a phone timer on the counter counts down from 20 minutes.”
Burn care is one of the few areas of first aid where what a bystander does in the first minutes can change the injury itself, not just how comfortable the person is. Skin keeps cooking after the heat source is gone. Cooling it properly stops that, and it can be the difference between a burn that heals in a week and one that needs a specialist.
This post explains why cooling works, how long and how cold, the things not to put on a burn, and which burns need emergency care. It is not a substitute for hands-on training, and it does not certify you in anything.
Why the burn keeps getting worse
When skin is burned, it does not stop being hot the moment the kettle or the pan is taken away. Heat stored in the tissue keeps spreading into the layers below. A burn that started on the surface can reach deeper skin over the next several minutes if nothing takes the heat out.
Cool water draws that heat out. It also reduces pain and swelling. This is why the length of cooling matters more than the exact temperature: a few seconds only cools the surface, while longer cooling reaches the heat that has soaked into the deeper tissue.
Image needed · diagram
burn-depth-superficial-partial-full-diagram.svg
Three side-by-side skin cross-sections with labelled layers (outer skin, deeper skin, fat). Superficial: redness in the top layer only. Partial thickness: into the deeper skin with a blister above. Full thickness: through all layers, surface pale or charred. A small downward arrow on the first panel labelled heat keeps travelling without cooling. Warm red and tan on charcoal line work, no gore.
Alt text ready: “Cross-section of skin showing three burn depths: superficial in the top layer, partial thickness into the second layer with a blister, and full thickness through all layers.”
How long, and how cold
Cool the burn under cool running tap water. MyHealth Alberta advises 10 to 20 minutes, and the Canadian Red Cross first aid manual says at least 10 minutes. In practice, set a timer or watch the clock, because two minutes feels like ten when someone is in pain.
Use cool water, not ice and not ice water. Ice can damage skin that is already injured and it is not more effective. If running water is not available, a clean cool compress, changed often, or immersion in a basin of cool water are the next best options.
Cooling works best when it starts quickly, but it is still worth doing if some minutes have already passed. Do not skip it because the burn happened a little while ago.
One caution: cooling a large burn, especially on a small child, can make them cold. Cool the burn, not the whole person. Keep the rest of their body covered and warm, and watch for shivering. standard child care first aid, for anyone caring for babies and small children.
While it cools
Take off rings, watches, bracelets and anything tight near the burn while you cool it. Burned skin swells, and jewellery that comes off easily now may have to be cut off later.
Remove clothing from the burned area if it comes away easily. If fabric has stuck to the skin, leave it and cut around it. Pulling it off tears the skin with it.
What not to put on a burn
Every family seems to have a remedy. Most of them trap heat in the skin, introduce infection, or have to be scraped off painfully at the hospital.
Leave these off:
- Ice or ice water.
- Butter, oil, grease or margarine.
- Toothpaste, egg white, mustard, or any other kitchen remedy.
- Creams, ointments or sprays before the burn has been assessed, if it is more than minor.
- Fluffy cotton wool or anything that will shed fibres into the wound.
- Do not break blisters. They protect the skin underneath.
After cooling, cover the burn loosely with a clean, dry, non-fluffy dressing or cloth. The cover keeps it clean and keeps air off it, which also eases the pain. Do not wrap it tightly, because it will swell.
Which burns need emergency care
Small, red, painful burns without blisters, like a brief touch on an oven rack, can usually be cared for at home. Many other burns cannot. Size matters, but so does where the burn is, how it happened, and who it happened to. the signs of smoke inhalation that still need a hospital.
| The burn | What to do |
|---|---|
| The person is having difficulty breathing, or was in smoke | Call 911. |
| Caused by chemicals, electricity or an explosion | Call 911. |
| Deep: white, leathery, charred, or strangely painless | Call 911. |
| Large, or a large area of blistered or broken skin | Call 911. |
| On the face, neck, hands, feet, groin, or over a joint | Get emergency care. |
| Goes all the way around an arm, leg, finger or the chest | Get emergency care. |
| On a baby, young child or older adult, and more than very minor | Have it seen by a doctor. |
Keep cooling the burn while you wait for help to arrive, unless the person is getting cold. how hospital and paramedic teams size a serious burn.
Quick answers
- How long should you run cold water on a burn?
- Cool running tap water for 10 to 20 minutes, according to MyHealth Alberta, and at least 10 minutes according to the Canadian Red Cross first aid manual. Most people stop far too early. Use cool water, not ice.
- Should you put ice on a burn?
- No. Ice and ice water can damage burned skin further and are no more effective than cool running water.
- Should you put butter or ointment on a burn?
- No butter, oil or kitchen remedies. They trap heat and can cause infection. After cooling, cover the burn loosely with a clean, dry dressing. Leave creams off anything more than a minor burn until it has been assessed.
- Should you pop a burn blister?
- No. The blister protects the skin underneath from infection. Leave it intact and cover it loosely.
- When does a burn need a doctor?
- Call 911 for burns with breathing difficulty or smoke exposure, chemical, electrical or explosion burns, deep burns, and large burns. Get emergency care for burns on the face, neck, hands, feet, groin or joints, and burns that go all the way around a limb. Burns on babies, young children and older adults should be seen unless very minor.
Sources
- Alberta Health Services (MyHealth.Alberta.ca): Run cool tap water over a heat burn for 10 to 20 minutes and do not use ice; remove jewellery before swelling; do not remove clothing stuck to the burn; cover with a clean, dry cloth; seek emergency care for burns on the face, hands, feet, groin or joints, burns encircling a limb, and inhalation injury. (checked 2026-09-23)
- Canadian Red Cross: First Aid and CPR manual: cool the burn for at least 10 minutes with water or a cool (not freezing) compress; remove jewellery and clothing but not anything stuck to the skin; cover loosely with a dry sterile dressing; monitor for hypothermia when cooling large burns, especially on children; call 911 for breathing difficulty, chemical, explosion or electrical burns, full thickness or large burns, and burns to the face, neck, hands or genitals. (checked 2026-09-23)