The short answer
- Tiredness, a headache and a dry mouth often come firstThirst can be the last thing to appear in an older person, so it is not a sign to wait for.
- The mouth and skin checks are less trustworthy in later lifeResearch on older patients has found these traditional signs can be present without dehydration, or absent with it.
- New confusion is worth checking on the same dayIt is one of the signs most often put down to something else, from a bad night to the start of dementia.
- Know what to do once you see the signsOffer a drink, watch what happens over the next few hours, and know when it is time to call the GP or 111.
The NHS names babies, young children and older adults as the groups most at risk of dehydration.
The signs, grouped
The signs of dehydration to check for, grouped by what they affect
Most of this is the NHS's own list of dehydration signs for adults, grouped here by what they affect rather than by the order it is usually listed, so it is easier to check against what you have noticed in your relative. A few signs that matter specifically in later life, covered below, have been added from other guidance.
Mind and energy
Unusually tired, or lacking energy
Often the first thing a family notices, and easy to put down to a bad night or a quiet day.
A headache, or feeling lightheaded
Common on its own, and worth checking against drinking before assuming it is something else.
New confusion, or more trouble concentrating than usual
Worth checking the same day. It is one of the signs most often mistaken for something else in later life.
Mouth, skin and eyes
A dry mouth, lips or tongue
Useful alongside other signs, though not reliable enough to rule dehydration in or out on its own in later life.
Sunken eyes
Worth noting alongside the other signs, without the same research caution behind it as the mouth and skin checks.
Skin that has lost some of its spring
Ageing skin is naturally less elastic anyway, which is why this sign is the least reliable of the three. More on that below.
Muscles and balance
Dizziness, or feeling lightheaded on standing
A common early sign, and one that raises the risk of a fall.
Feeling unsteady on their feet
Worth treating with the same caution as a dizzy spell.
Muscle cramps in hot weather
Tied more to heat and sweating than to everyday under-drinking, but worth watching for in summer.
Waterworks
Dark yellow or strong-smelling urine
One of the clearer signs, and one worth checking directly rather than guessing.
Passing urine less often than usual
Easy to track over a day without needing to ask anything awkward.
Not every sign needs to be present for it to be dehydration, and one or two on their own do not confirm it either. Most of this is the NHS's own list for dehydration in adults, which names babies, young children and older adults as the groups most at risk. New confusion, feeling unsteady on their feet, muscle cramps in hot weather, and skin that has lost some of its spring are added from NICE, Age UK, British Geriatrics Society and geriatric dehydration-screening research, because they are signs that matter specifically in older people. How serious is dehydration in the elderly? groups these same signs into three stages, from mild through to the point where it needs a 999 call, and covers the health problems dehydration can lead to if it is missed. This page stays with recognising the signs; that one covers what they add up to.
Why some signs mislead
Why the mouth and skin checks are less reliable in later life
A dry mouth and skin that has lost its spring are the checks most people reach for first, largely because they are the easiest to see. In an older person they are also the least trustworthy of the signs above, and it helps to know why before you rule dehydration in or out on the strength of them alone.
What to check
- Urine colour and how often they are going, which tends to be a clearer sign in later life than the mouth or skin checks
- Whether anything feels different to your relative today, not only what you can see
- Any new confusion, treated as worth checking the same day even without other signs
- A change from what is normal for that person, rather than a general checklist
What not to rely on alone
- The skin-pinch test on its own. Ageing skin naturally loses some of its spring, so this sign shows up in people who are not dehydrated too
- A dry-looking mouth as proof either way by itself
- Waiting for thirst as the trigger to offer a drink
- Putting new confusion down to "just a bad day" without checking how much they have had to drink
A study validating a dehydration screening tool for older patients found that physical signs such as skin turgor, a dry mouth and low blood pressure on standing were too unreliable on their own to include, because they can be confounded by the ordinary physical changes of ageing, by long-term conditions, and by the number of medicines many older people take. That is not a reason to stop checking them, only a reason to check the fuller list above alongside them, and to trust a change from what is normal for your relative over a single sign in isolation.
What to do next
What to do once you notice the signs
Most dehydration in older people is mild and put right within a day. These are the steps to take once you have spotted one or more of the signs above.
- 1
Offer a drink now
Straight awayWater, squash or tea all count. If your relative is reluctant, or usually drinks very little, the practical suggestions in how can I get my elderly relative to drink more fluids may help. - 2
Watch what happens over the next few hours
Same dayCheck urine colour and whether energy and confusion improve once fluids are on board. Keeping a rough note of what they have had to drink makes this easier to judge. - 3
Call the GP or NHS 111 if nothing improves
If in doubtAsk for an urgent appointment or call 111 if the signs do not ease, or straight to 999 if you see confusion that has come on suddenly, pale or grey skin, or breathing difficulty. How serious is dehydration in the elderly? sets out exactly which signs mean which call. - 4
Consider a regular visit for ongoing watching
Longer termA carer who visits at the same times each day gets to know what is normal for your relative and notices sooner when a drink has gone untouched. Companion carers on PrimeCarers charge £15 to £20 an hour with our fee included.
Tea counts towards that fluid total too. Caffeine has a mild diuretic effect, but at the amount most older people drink in a day it does not cancel out what the cup puts back in, as does tea count as water intake? explains in more detail.
Questions
Questions families ask about the symptoms
Tiredness, a headache or a dry mouth tend to appear before thirst does, because the sense of thirst is often the first thing to fade with age. That is why it helps to offer drinks on a routine rather than waiting to be asked.
Yes. New or sudden confusion is one of the signs of dehydration in later life, and it is also one of the signs most often mistaken for something else, from a bad night to the start of dementia. How serious is dehydration in the elderly? covers what confusion can be linked to if dehydration is missed.
Not reliably. Research on screening older patients for dehydration found that traditional physical checks, including dry lips and skin that has lost its spring, can be misleading in later life, because ageing skin and long-term conditions can produce similar signs on their own. They are still worth checking alongside the fuller list, just not trusted by themselves.
A pale straw colour is the usual sign of good hydration. Urine that is dark yellow or strong-smelling, or noticeably less frequent than usual, points the other way and is one of the clearer signs to check.
Call 111 or ask for an urgent GP appointment if dizziness, a faster heart rate or dark urine do not settle. Call 999 for pale, grey or blotchy skin, skin that feels cold, difficulty breathing, confusion that has come on suddenly, or being unusually sleepy and hard to wake. How serious is dehydration in the elderly? sets out the full list.
Yes. A carer who visits regularly gets to know what is normal for your relative, so a change such as a cup left untouched or a quieter mood than usual is easier to notice. Companion carers on PrimeCarers charge £15 to £20 an hour with our fee included. How much does a companion carer cost? has the detail.