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Hydration, dehydration and heatstroke

Dr Roger Henderson
Reviewed by Dr Roger HendersonReviewed on 13.10.2023 | 2 minutes read

Ensuring adequate hydration to ensure our bodies remain healthy can be a tough ask, especially in hot conditions, and during strenuous activities or exercise. Hot temperatures and increased water and salt losses can lead to dehydration. Mild dehydration may be felt as thirst, headache, mild dizziness, reduced need to urinate and dry skin. In its more severe form, dehydration can result in reduced alertness, fatigue, muscle cramps, loss of consciousness and long term damage to your kidneys.

Doctor’s advice

What to watch out for

Inadequate intake of fluids is a leading cause of dehydration with many people not ensuring that they have the recommended 2 - 2.5 litres of fluids a day. Mild dehydration during the summer months is very common however if combined with a high amount of sun exposure it can result in heat exhaustion or heatstroke.

Symptoms of heat exhaustion include headache, dizziness, nausea or vomiting and high temperature. If this occurs the patient needs to be cooled down with cold drinking water and moist tepid cold sponges applied to the face and body. Don’t use ice packs. If this does not result in an improvement in symptoms after 30 minutes they may be at risk of developing heatstroke.

What are the symptoms of heatstroke?

Symptoms of heatstroke include; confusion, not sweating despite feeling hot, high temperature (usually over 40 degrees), drowsiness and reduced consciousness, and in severe cases seizures. Anyone with these symptoms needs to be treated as an emergency and should be transferred to a hospital without delay.

How can I avoid dehydration?

Dehydration can be prevented with regular fluids and increased awareness of activities that can result in dehydration such as exercise and alcohol use. Although water and fluids from other drinks are often sufficient, some drinks are marketed as providing additional hydration and salt depletion support for those completing in regular sporting activities.

If you have already become dehydrated then oral rehydration salts mixed with water can help replace the water and essential salts that your body needs for brain and body functioning. If you have diarrhoea it is recommended that you have a sachet after each loose stool, whilst not exceeding the recommended dosages.

When should I see my doctor?

If you have been unable to keep down fluids for over 12 hours or have had severe diarrhoea or are feeling weak then it is best to be reviewed by your doctor. If you have any of the symptoms of heatstroke then you should be attending the hospital without delay.

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Dr Roger Henderson
Reviewed by Dr Roger Henderson
Reviewed on 13.10.2023