How to spot the signs of dehydration and fix it

How to spot the signs of dehydration and fix it.

How to spot the signs of dehydration and fix it

Estimated reading time: 7 minutes

Dehydration occurs when you use or lose more fluid than you take in, and your body doesn’t have enough water and other fluids to carry out its normal functions. Or to put it another way, a harmful reduction in the amount of water in the body.

How to spot the signs of dehydration and fix it

What does dehydration look and feel like?

Medically we have things called “signs” and “symptoms”. Signs are a bit like road signs – you can see them. Symptoms are things that the patient can tell you – they have a headache, etc. In no particular order, the signs and symptoms of dehydration can include;

  • feeling thirsty or hungry
  • dark yellow (or darker) and strong-smelling urine
  • constipation
  • a racing heartbeat
  • your skin loses its typical elasticity
  • feeling dizzy or lightheaded, irritable, or forgetful
  • they’re feeling cold on a cold day
  • mental confusion leading to irrational behaviour
  • feeling tired
  • progressive weakness in the arms and legs
  • a dry mouth, lips and eyes
  • dried salty sweat stains on hats and shoes
  • muscle cramps
  • producing little urine and urinating fewer than 4 times a day
  • declining sweat rate,
  • rising body temperature
  • nausea & vomiting
  • seizures
  • brain damage

Lots of other medical conditions can include these symptoms, so it may not be dehydration that the patient is suffering from. You can find yourself dehydrated more easily if you have:

  • diabetes
  • vomiting or diarrhoea
  • been in the sun too long (heatstroke)
  • drunk too much alcohol
  • sweated too much after exercising
  • a high temperature (above 38C)
  • been taking medicines that make you urinate more (known as diuretics)

Why is dehydration a problem?

Your body is amazing. It’s an electro-chemically controlled, bio-mechanical “machine” working with a myriad of symbiotic relationships with billions of other creatures and bacteria. Without these symbiotic relationships or the correct balance of chemicals, it wouldn’t work well, and you’d be very ill or worse.

The human body is largely made up of water. Overall, this can be 50-70% but this depends on the part of the body (e.g. teeth aren’t 70% water!).

Quite a lot of the water in your body is in your blood. How much blood you have is entirely dependent on your size and body makeup. If anyone tells you that you have 8 pints/5 litres of blood, you might, but you probably don’t.

Without the correct amount of water in your system, the various functions of your body won’t work as well as they could do, if at all.

What about salts?

You will probably have heard of people saying, “you need to keep your salts up”. But what does this actually mean? We’re not talking about spooning down table salt (sodium chloride, NaCl) as too much of that will actively dehydrate you.

You need to be in balance.

What you need is to take in the correct amount of fluid to keep everything working nicely. That fluid needs to contain the correct amount of salts to help your heart beat, your brain, your enzymes and all those other technical things your vaguely remember from school biology, all work properly.

The medical term for having low sodium in your system is hyponatremia. Technically, this is when the sodium levels fall below 135 millimoles per litre (mmol/l). The symptoms of hyponatremia are covered in the list above.

Do you remember the line from the Rhyme of The Ancient Mariner; “Water, water everywhere. And not a drop to drink”?

Well, if you drink (consume) too much salt, your liver and kidneys will hopefully do their thing (filtering the blood) and you will flush out the excess salt in your urine. But urine is created using the bodies stored water. So, if you start to consume high concentrations of salt, you will effectively dehydrate yourself as your body flushes out the excess salt.

Should I drink two litres of water each day?

In 1945, the US Food and Nutrition Board of the National Research Council stated: “A suitable allowance of water for adults is 2.5L/day. An ordinary standard for diverse persons is 1ml for each calorie of food. Most of this quantity is contained in prepared food”.

The critical element to this statement is the last sentence; “Most of this quantity is contained in prepared food”.

While you don’t need to “drink” 2 litres of water per day, you should aim to “consume” 2 litres (or more) per day. In the UK, the current guidance is to drink 6-8 glasses of fluid per day, which is roughly 1.2 litres. (Source: However, this figure entirely relates to your physical activities, your age, your personal health & the ambient temperature and wind speed (windchill or hot and drying wind).

So, while it’s generally safe to drink 2 litres of water per day, you could also overdo it!

If you do consume too much water you run the risk of over-diluting your bodies electrolytes, resulting in water intoxication. This can commonly lead to the psychological effects of disengaging from our “gut instincts”, leading to poor decision making.

What should you do if someone is dehydrated?

Put simply, you need to help them to rehydrate.

There are numerous branded rehydration powders and liquids on the market that you can choose from. There also seem to be a million and one different recipes that you can find on the internet. However, the most basic recipe is as follows:

  • 1 litre of water
  • 1 tsp of sugar
  • 0.5tsp of salt

Ordinary tap water and granulated sugar are perfectly fine. As for the salt, table salt is ok, but if you have a different sort that you can finely grind, that would be better. Himalayan salt would be ideal. Note that Epsom salts are magnesium sulphate, rather than a sodium-based chemical. Personally, when I’m making some up for myself, I also add a dash of blackcurrant cordial to the mix to make it taste a bit more palatable. However, you can also add a vitamin C tablet as they tend to have a taste of oranges and will give you additional chemical benefits.

If you’re a carer, the NHS recommend that you;

  • make sure they drink during mealtimes
  • make drinking a social thing, like “having a cup of tea”
  • offer them food with a high water content – for example, soups, ice cream or jellies, or fruits like melon

If you have a baby or child whom you suspect is dehydrated (see list below), take them to medical professional without delay. For further reassurance, click here to have a look at the NHS website.

  • seem drowsy
  • breathe fast
  • have few or no tears when they cry
  • have a soft spot on their head that sinks inwards (sunken fontanelle)
  • have a dry mouth
  • have dark yellow pee or have not had a pee in last 12 hours
  • have cold and blotchy-looking hands and feet


As the UK goes through its latest heatwave, with record breaking temperatures, we’re all thinking about dehydration. Hopefully this blog will have answered a few questions and given you a few tips on what to look out for.

Do you have a family favourite recipe for rehydration? If so, let us know in the comments below.

Dehydration, along with many more subjects, is covered in our multi-day first aid courses, such as

  • 16 hour Outdoor first aid
  • Forest School First Aid
  • First aid at work +F (Forestry Commission compliant)

If you’d like to discuss your training, email me now.

Chris Garland. Founder and lead instructor at Chris Garland Training.
Chris Garland. Founder and lead instructor at Chris Garland Training.
How to spot the signs of dehydration and fix it

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