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Heat-related illness in babies

If your baby has symptoms of heatstroke and is not responding or breathing normally, immediately call triple zero (000) and ask for an ambulance.

If your baby is younger than 3 months old and has a fever above 38°C, seek urgent medical attention or go to the nearest hospital emergency department.

Key facts

  • Heat-related illnesses happen when your body overheats and cannot cool down, causing a range of illnesses from mild heat exhaustion to life-threatening heatstroke.
  • Your baby can develop a heat-related illness if they spend a lot of time in hot weather, are overdressed or left inside a parked car — even for a short time.
  • If your baby has heatstroke, they need urgent treatment in hospital, where they will be cooled, given fluids and monitored.
  • To prevent your baby from overheating, avoid the heat, dress them appropriately for the season, follow safe-sleep recommendations and never leave them in a parked car.

    • What is a heat-related illness?

    Heat-related illnesses happen when your body overheats and cannot cool down. They range from mild heat rash (Opens in new tab) to life-threatening heatstroke (Opens in new tab).

    Children, especially babies, are at a higher risk of developing heat-related illnesses. They do not sweat as much as adults and cannot regulate their body temperature as well. It is important to prevent your baby from overheating.

    Other people at a higher risk of heat-related illnesses include:

    What is heat stress?

    Your baby can develop heat stress if their temperature rises above 37.5°C faster than they can cool down. This can happen from brief exposure to intense heat or longer exposure to mild heat.

    What is heat exhaustion?

    Heat exhaustion is a mild-to-moderate heat-related illness. It happens when your baby's body temperature is between 38.3°C and 40°C. This is more severe than heat stress.

    What is heatstroke?

    Heatstroke is a severe heat-related illness. It is a rare and life-threatening medical emergency. Your baby's temperature rises so high that their central nervous system (Opens in new tab) (CNS) and other organs are affected. Your baby needs urgent medical attention for heatstroke.

    What is severe dehydration?

    Severe dehydration happens when your baby loses too much fluid (at least 11% of their weight). This is a medical emergency. It can cause serious complications.

    What are the symptoms of a heat-related illness?

    Heat-related illnesses cause a range of symptoms. It is important to recognise these symptoms and know what to do.

    Heat stress

    If your baby develops heat stress, their temperature will be between 37.5°C and 38°C. They might be sweating and breathing quickly.

    Heat exhaustion

    If your baby has heat exhaustion, they might:

    Promotional tile for the infographic on Fever in babies and children.

    A handy guide on what to do if your baby has a fever.

    Heatstroke

    If your baby has heatstroke, they will have symptoms showing that their brain and nervous system are not working properly, such as:

    Your baby may also have:

    • hot and dry skin because they cannot sweat anymore
    • low blood pressure
    • temperature over 40°C
    • fast heart rate and breathing

    Severe dehydration

    If your baby is severely dehydrated, they may be less alert or hard to wake up. They also may have:

    • pale or blotchy skin
    • cold limbs
    • sunken eyes
    • low blood pressure, fast heart rate or breathing quickly
    • sunken fontanelle on their head

    CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

    What causes a heat-related illness?

    Your baby can develop a heat-related illness if they:

    • spend a lot of time outdoors
    • don't drink enough, and can't cool down properly
    • are overdressed
    • are left in a parked car, even for a short time — the temperature inside your car can rise very quickly to extreme temperatures
    • have a dry cloth draped over their stroller or capsule (for example, to create shade)
    • have a fever or a medical condition that makes it hard for them to control their temperature

    Read about babies in hot weather.

    How is a heat-related illness diagnosed?

    Your baby's doctor can diagnose a heat-related illness by:

    • assessing their symptoms and examining them
    • measuring their vital signs, including their body temperature
    • requesting blood tests
    • asking you about your baby's medical history and exposure to hot weather

    FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

    When should I see my doctor?

    Take your baby to their doctor if you suspect they have heat exhaustion or are unwell. Don't wait — trust your instinct.

    When to seek urgent care

    If your baby has symptoms of heatstroke and is not responding or breathing normally, immediately call triple zero (000) and ask for an ambulance.

    If your baby is younger than 3 months old and has a fever above 38°C, seek urgent medical attention or go to the nearest hospital emergency department.

    While waiting for the ambulance:

    • cool your baby in a lukewarm bath; if you do not have a bath, sponge your baby
    • repeatedly moisten your baby's skin with a moist cloth or spray
    • continuously fan your baby
    • give your baby liquids (only if they are awake and can swallow)

    How is a heat-related illness treated?

    Your baby's treatment depends on how severe their heat-related illness is.

    Self-care at home

    If your baby has heat exhaustion, treatment at home includes:

    • removing them from the heat to a cool spot
    • removing extra layers of clothing
    • spraying them with lukewarm water
    • giving them fluids if they are dehydrated
    • watching them until their symptoms go away

    If symptoms do not improve, seek urgent care.

    Treatment of heatstroke

    If your baby has heatstroke, they need treatment in hospital. Treatment includes:

    • cooling your baby down as quickly as possible — they may be immersed in cool water; fans will be positioned to blow cool air across their body
    • if severely dehydrated, they will get intravenous (IV) fluids
    • continuous monitoring to track their progress
    • treatment of any complications

    What are the complications of a heat-related illness?

    Heat-related illnesses can cause complications, including:

    • seizures
    • loss of consciousness
    • dehydration
    • death

    Heat stress and hyperthermia are also linked to sudden infant death syndrome (SIDS).

    Can a heat-related illness be prevented?

    Here are some tips to prevent heat-related illnesses:

    • Keep your baby in cool and ventilated spaces. Avoid exposing your baby to the sun on very hot days.
    • Make sure your baby is hydrated.
    • Put sunscreen on your baby if they are older than 6 months.
    • Make sure your baby is not overdressed.
    • If you want to shade your baby, drape a light-coloured and moist muslin cloth over their pram with a fan blowing air inwards. Do not cover your baby's pram with a dry cloth.
    • Never leave your baby in a parked car. Not even for a couple of minutes.
    Keeping your baby cool in hot weather infographic promotional tile.

    Tips on keeping your baby cool in hot weather.

    Here are some tips to prevent your baby from overheating when sleeping:

    • Put your baby to sleep on their back, with their head uncovered.
    • Your baby should sleep on light, cotton sheets.
    • Your baby should sleep in a ventilated and comfortable room. Keep heaters away.
    • Make sure air can circulate around their cot.

    Read about keeping babies cool in hot weather.

    Read about dressing a newborn.

    Read about sun and heat protection for babies and kids.

    Resources and support

    Looking for information for Aboriginal and/or Torres Strait Islander people?

    NSW Health has a 'Beat the Heat (Opens in new tab)' resource for Aboriginal and/or Torres Strait Islander people.

    Do you prefer to read in languages other than English?

    NSW Health has translated its resource about keeping babies safe in the heat (Opens in new tab) into many community languages.

    Speak to a maternal child health nurse

    Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 (Opens in new tab) or video call. Available 7am to midnight (AET), 7 days a week.

    Last reviewed: February 2025

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