Dehydration occurs when your body loses more fluid than you take in. It can be mild, moderate, or severe, based on how much of your body’s fluid is lost.
If severe dehydration develops and is left untreated it can be serious. It can cause kidney damage, seizures, brain damage and may even be fatal. It requires hospital treatment and an intravenous drip to restore the substantial loss of fluids.
Anyone may become dehydrated, but the condition is especially dangerous for babies and young children, older adults and people with long-term illnesses. If you think you or someone with you is severely dehydrated, get them to hospital.

Causes of dehydration.

Possible causes of dehydration include:
• Excessive sweating as a result of vigorous exercise, especially in hot weather
• Severe vomiting or diarrhoea
• Drinking too much alcohol
• Heatstroke
• Fever
• Urinating too much (uncontrolled diabetes or some medications, such as diuretics, can cause you to urinate a lot)
• Not drinking enough water (perhaps through illness or in hot weather)

Symptoms of dehydration.
Signs and symptoms of dehydration vary depending on the degree of dehydration.

Mild to moderate dehydration symptoms:

• Thirst
• Headache
• Dark coloured and strong smelling urine
• Passing urine less often than usual
• Dizziness or light-headedness
• Tiredness
• Dry mouth, lips and tongue
• Dry eyes and no tears when crying
• Dry, cool skin
• Muscle cramps
• A drop in weight

Severe dehydration symptoms:

• Not urinating or minimal dark yellow urine
• Dry looking skin with loss of skin elasticity
• Dizziness or light-headedness
• Rapid heartbeat and low blood pressure
• Rapid breathing
• Sunken eyes
• Listlessness
• Unconsciousness or delirium
• Extreme thirst
• Irritability, drowsiness or confusion
• Very dry mouth
• Fever
• Fits (seizures)

Dehydration symptoms in babies:

• Sunken soft spot (fontanelle) on their head
• No tears when crying
• Sunken eyes, cheeks
• Dry mouth and tongue
• Fewer wet nappies
• Dark yellow urine
• Drowsiness
• Fast breathing
• Cold and blotchy-looking hands and feet
• Listlessness or irritability