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Signs of dehydration in babies, infants and children

Dehydration can be fatal, and babies and children are particularly vulnerable. It’s therefore important to recognise the signs of dehydration.

Babies and young children are much more likely than adults to become dehydrated when they have diarrhoea. They can become very sick very quickly and may need to go to hospital. Signs that a child is dehydrated include:

  • dry mouth, tongue and lips
  • sunken eyes
  • being listless or irritable
  • shedding fewer tears when crying

Severe dehydration is a medical emergency and can be fatal — get medical help for your child immediately.

Symptoms include:

  • not drinking much or refusing drink
  • feeling lethargic
  • producing no urine or only a very reduced amount of urine
  • very sunken eyes
  • very sunken fontanelle in a baby
  • cold, pale or blotchy skin
  • fast breathing

When should my child see a doctor?

Got to a doctor or your local hospital emergency room straightaway if a child with diarrhoea:

  • is younger than 6 months or weighs less than 8 kg
  • was born preterm, or has ongoing health problems
  • has blood or mucus in their stool (poo) — this suggests a bacterial infection
  • has severe abdominal pain or constant tummy pain
  • is a baby and is doing fewer than 4 wet nappies per day
  • has green vomit
  • keeps vomiting
  • has a high fever
  • shows signs of dehydration (see above)
  • cannot take in enough fluids
  • is tired or drowsy
  • has other worrying symptoms, such as headache or pain when weeing
  • is not getting any better
  • Dehydration

    Dehydration is when a casualty has an excessive loss of body fluid. This condition occurs when the amount of water leaving the body is greater than the amount being taken in. The percentage of the human body that is water varies between 55% to 78% depending on a person’s age and sex; this makes adequate consumption of water essential. The causes of dehydration include prolonged exposure to heat and humidity, diseases of the gastrointestinal tract that cause vomiting and/or diarrhoea, prolonged vigorous exercise (e.g. in a marathon), kidney disease and medications (diuretics). Although we lose water routinely a balance must be maintained to avoid dehydration which can lead to shock and be life-threatening particularly in young children and the elderly.
    The body routinely loses water through:

    Breathing and humidified air leaving the body.

    Perspiring to cool the body.

    Urination or having a bowel movement to rid the body of waste products.


    Follow the DRSABCD emergency action plan.

    Cease activity and remove from hot environment.

    Rest in shade.

    Remove unnecessary clothing.

    Give cool sips of water.

    Seek medical advice once recovered.

    If casualty does not improve or condition deteriorates call 000 for an ambulance.

    Heat Cramps

    Heat cramps are painful muscle spasms in the abdomen, arms or legs following strenuous activity. Heat cramps often are caused by a lack of salt in the body, but salt replacement should not be considered without advice from a medical professional. Heat cramps usually affect people who sweat a lot during strenuous activity. The sweating depletes the body’s salt and moisture. Heat cramps may also be a symptom of heat exhaustion.

    Painful muscle cramps in the limbs or abdomen.

    Uncontrolled spasms of affected limbs.

    Pale, clammy skin.

    Nausea and/or vomiting.

    Tiredness, dizziness or weakness.

    Sweating if associated with exertion.

    Cease activity and remove casualty to a cool place to rest.

    Lay the casualty down with legs slightly elevated.

    Gently stretch the affected muscles.

    Remove unnecessary clothing.

    Apply a cold compress to affected muscles.

    Replace lost fluid with sips of cool water; give slowly if casualty is nauseated.

    DO NOT rub or massage the affected limb.

    DO NOT perform any further exercise.

    Heat Exhaustion

    Heat exhaustion is the body’s response to an excessive loss of water and salt contained in sweat. It is a warning that the body is getting too hot and generally develops after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids. Those most susceptible to heat exhaustion are elderly people, people with high blood pressure and people working or exercising in a hot environment.

    Cramps in the limbs and/or abdomen.

    Profuse and prolonged sweating.

    Persistent headache.

    Thirst, nausea and/or vomiting.

    Giddiness and fainting.

    Exhaustion and lethargy.

    Rapid breathing and shortness of breath.

    Pale, cool, clammy skin.

    Rapid, weak pulse.


      Follow the DRSABCD emergency action plan
      Complete rest in a cool environment.

    Lay the casualty down.

    Reassure the casualty.

    Remove unnecessary clothing.

    Moisten the skin with a moist cloth or atomiser spray.

    Cool by fanning.

    Give frequent small sips of water if fully conscious and not nauseated.

    Call 000 for an ambulance.

    Monitor the casualty, if casualty becomes unconscious follow DRSABCD.

    If dehydration or heat exhaustion is left untreated they may lead to heatstroke.

    Heat Stroke

    Heat stroke is a form of hyperthermia, an abnormally elevated body temperature with accompanying physical and neurological symptoms. Unlike heat cramps and heat exhaustion, two forms of hyperthermia that are less severe, heat stroke is a true medical emergency that can be life-threatening if not treated promptly and appropriately.

    The body normally generates heat as a result of metabolism, and is usually able to dissipate the heat by either radiation of heat through the skin or by evaporation of sweat. However, in extreme heat, high humidity, or vigorous exertion under the sun, the body may not be able to dissipate the heat and the body temperature rises, sometimes up to 41.1°C or higher. Another cause of heat stroke is dehydration. A dehydrated person may not be able to sweat fast enough to dissipate heat, which causes the body temperature to rise.

    Heat Stroke can be caused by:

    Hot climates.

    Infection and illnesses.

    Insufficient fluid intake.

    Overdressing for the climate.

    Physical exercise.


    Nausea and/or vomiting

    Flushed, hot, dry skin (no sweating).


    Visual disturbances.

    Irritability, mental confusion, aggression.

    Staggering gait, fatigue.



    Body temperature 40°C or more.

    Strong pounding rapid pulse, gradually weakening.

    Collapse, unconsciousness leading to coma.

    Call 000 for an ambulance urgently.

    Follow the DRSABCD emergency action plan.

    Remove casualty to a cool environment to rest.

    Loosen and remove any unnecessary clothing.

    Moisten the skin with a moist cloth (cover with a wet sheet) or atomiser spray and fan repeatedly.

    Apply wrapped ice packs to neck, groin and armpits.

    Continue until body feels cool to the touch, and then stop.

    Give casualty sips of cool fluid if fully conscious. DO NOT give if the casualty is semi-conscious or unconscious. Re-hydration will need to be via intravenous fluids administered by the ambulance or medical personnel.

    Monitor the casualty and be prepared to commence CPR.

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