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Hydration in a nutshell

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 3 minutes read

Hydration, in its simplest form, is to supply and retain water in the body's tissues. Take in too little water, and you risk dehydration, making it hard for the body to carry out essential functions. And with loss of water, you lose essential salts and minerals, causing further turmoil in your body.

We've all experienced mild dehydration at times, like when the weather is hot, or we are doing a sweaty workout. Fighting a fever or a stomach bug also leaves you lacking hydration.

But you might have overlooked the toll a flight can take on your body. An airline cabin draws air in from the upper atmosphere for us to breathe in, and this is very dry. The cabin air can be less humid than the Sahara Desert, and you actually lose water through your breath. Telling signs can be a dry feeling in your nose and throat, your contact lenses feeling scratchy, and you might be passing urine less, or it's dark and strong-smelling.

You might feel thirsty, but this is actually a late sign, as when thirst sets in, your body is already 2% dehydrated. You need to work hard to replace this. Your body will work best if you can plan ahead to avoid dehydration, rather than playing catch-up.

If you're traveling with little ones, they have a higher body surface area and breathe a bit faster, so they can become dehydrated even more quickly, and salt imbalance follows. It can be tempting to let them snooze through the flight (and give you some peace), but feeling tired and sleepy can also be a sign of dehydration, so make sure they have topped up before nodding off.

Doctor’s advice

How can I prevent dehydration?

As soon as you feel thirsty, you should reach for the fluids. Water is a good place to start. Try small sips, little and often, especially if you're finding it difficult to keep things down.

Stomach bugs and infections can hit us all, especially when we're traveling and meet the germs of a new country. If you get a vomiting and diarrhea bug, or you catch the flu, you need to drink more than usual. Your immune system is fueled by water when fighting an infection, so bear these increased requirements in mind with a virus or gastroenteritis.

Healthwords pharmacists' top tips

When you are losing fluid through a sweaty workout, heatwave, or diarrhea, you are losing more than just water. You are losing important salts such as sodium. If you were to drink simply water, your body would lose most of it, and you would continue to lose the important salts at the same time.

Hypotonic solutions are best for straightforward hydration. These have a lower concentration of salts and sugar than in the body, making them ideal to replace losses. Most oral rehydration solutions or salts fall into this category. When taking O.R.S Hydration Tablets, the glucose helps get the sodium that is also included back into the body. This creates a path for water molecules to follow the sodium. It's a game of follow-the-leader back into the body's cells: glucose first, then sodium, then water.

It's a win-win to feeling better, as O.R.S side-steps the calories while imitating your body's natural balance.

When should I see my doctor?

As dehydration becomes more serious, you may feel lethargic and irritable, you may be breathing faster, and your heart may be racing, your skin will be dry, cold, and less elastic, and your eyes may be sunken.

You should seek urgent advice if you have any severe symptoms of dehydration, such as feeling unusually tired or drowsy, if you're confused or disoriented, or if you have fits or faints, or dizziness when you stand up.

You should also consider seeing your doctor sooner rather than later if you have other medical conditions, such as diabetes, that might make you at higher risk of dehydration than others.

Will dehydration affect my work performance?

It certainly can - even 1 to 2% of dehydration can have an effect on motor skills and mental performance.

Prevention is better than cure, so plan ahead and remember to keep a bottle of water or hydration solution handy during your shift or meetings, and top up throughout the day. If you think you have mild dehydration, you can top up gradually, and this shouldn't keep you away from work.

Depending on the nature of your work, be cautious – if you are very dehydrated, you may need to postpone work or meetings.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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