Older adults are more likely to become dehydrated than younger people, and it can happen gradually without them noticing. The sense of thirst weakens with age, the kidneys become less able to hold on to water, and some common medicines, especially water tablets (diuretics), increase fluid loss. Memory problems, difficulty getting to the toilet, worries about leaking urine and needing help to get drinks all make it more likely. The NHS lists babies, children and older adults as the groups most at risk. Signs include dark, strong-smelling urine, peeing less often, dizziness, tiredness and confusion, but in older people the usual signs can be unreliable, so regular drinking matters more than waiting for symptoms. Aim for 6 to 8 cups or glasses of fluid a day unless your doctor has advised otherwise.
Why older adults are at higher risk
- Less thirst: in a classic New England Journal of Medicine experiment, healthy men in their late 60s and 70s went without water for 24 hours. Compared with younger men, they felt less thirsty and drank less afterward, so their bodies didn’t return to normal hydration.
- Kidney changes: with age, the kidneys are less able to concentrate urine, so more water is lost.
- Less body water: older adults have less muscle, which holds water, and so smaller reserves.
- Medicines: diuretics, some blood pressure medicines and laxatives increase fluid loss.
- Health conditions: diabetes, kidney disease, dementia, stroke and infections all raise the risk.
- Practical barriers: difficulty swallowing, limited mobility, poor eyesight, or relying on others to bring drinks.
- Cutting back on purpose: some people drink less to avoid getting up at night or because of bladder leaks.
Signs of dehydration
The NHS lists these common symptoms:
- Feeling thirsty
- Dark yellow, strong-smelling pee
- Peeing less often than usual
- Feeling dizzy or lightheaded
- Feeling tired
- A dry mouth, lips and tongue
In older adults, dehydration can also show up as confusion, falls, constipation, headaches or a sudden change in behavior. A Cochrane review found that no single sign, such as a dry mouth or skin that stays tented when pinched, was reliable on its own for spotting dehydration in older people. That’s why regular drinking is the best protection, and why carers should take a change in alertness seriously.
When to get help
Get an urgent GP appointment or call NHS 111 (or your local equivalent) if dizziness when standing doesn’t go away, if pee stays dark or you’re peeing much less than normal, or if symptoms don’t improve after drinking more.
Call emergency services or go to the emergency department if someone:
- Is unusually tired or drowsy
- Is breathing quickly or has a fast heart rate
- Has blue, grey, pale or blotchy skin, lips or tongue
These can be signs of serious dehydration that needs urgent treatment. Sudden confusion in an older person also needs prompt medical attention, whatever the cause.
How much should older adults drink?
The NHS recommends 6 to 8 cups or glasses of fluid a day for adults, about 1.5 to 2 liters. The European Food Safety Authority sets an adequate total water intake of 2.0 liters a day for women and 2.5 liters for men, including the water in food, and applies the same values to older adults. You’ll need more in hot weather, during illness with fever, vomiting or diarrhea, and when you’re more active.
A practical check is urine color: pale straw yellow usually means you’re drinking enough. Some medicines and vitamins can change the color, so this isn’t perfect.
People who need to limit fluids
Some people with heart failure, advanced kidney disease or certain other conditions are told to restrict fluids. If that applies to you, follow your doctor’s advice rather than general guidelines.
What counts as fluid?
- Water, still or sparkling.
- Milk, including lower-fat milks and fortified plant milks, which also add protein and calcium.
- Tea and coffee: both count. The NHS includes them in your daily fluid intake. Large amounts of caffeine can make some people pee more, so decaf is a useful option later in the day.
- Soups, smoothies and jelly.
- Water-rich foods: fruit and vegetables such as watermelon, cucumber, oranges, tomatoes and lettuce, plus yogurt. Our guide to cucumber nutrition covers one of the most watery.
Alcohol doesn’t help hydration and can make you pee more, so it shouldn’t count toward your total.
Tips to drink more
- Drink at set times: a glass on waking, with every meal, mid-morning, mid-afternoon and with medicines.
- Keep a drink within reach, such as a jug of water or a bottle by the chair and the bed.
- Use a marked bottle or a simple tally to track how much you’ve had.
- Choose cups that are easy to hold, light, with handles or a lid and spout if hands shake.
- Offer variety: flavored water, herbal teas, diluted squash with no added sugar, milky drinks and soups. Our flavored water ideas can help.
- Drink more earlier in the day if night-time trips to the toilet are a worry, and less in the two hours before bed.
- Talk to your doctor about bladder problems rather than cutting back on drinks. Drinking too little can make the urine more concentrated and irritate the bladder.
Tips for carers and family
- Offer drinks regularly rather than asking “Do you want a drink?”, which is easy to refuse.
- Make drinking social: have a cup of tea together.
- Watch for signs such as fewer toilet trips, dark urine, constipation, new confusion or drowsiness.
- Pay extra attention in hot weather, after a fall and during illness. Our guide to staying hydrated in hot weather has more tips.
- In care homes, ask how fluid intake is recorded and how drinks are offered between meals.
Dehydration during illness
If someone has vomiting or diarrhea, they lose salts and minerals as well as water. The NHS advises small, frequent sips, and a pharmacist can recommend an oral rehydration solution to replace what’s lost. Older adults taking diuretics, blood pressure medicines or diabetes medicines such as SGLT2 inhibitors or metformin should ask their doctor or pharmacist whether to pause any of them while they’re unwell, as some can cause problems when you’re dehydrated.
Common questions
How can you tell if an elderly person is dehydrated?
Look for dark urine, peeing less, dry mouth, dizziness, tiredness, constipation and sudden confusion. Signs can be subtle, so if in doubt, ask a doctor or nurse to check.
Can dehydration cause confusion in older people?
Yes. Dehydration can cause confusion, and it can also make existing dementia worse. New confusion always needs medical attention, as it can have other causes, such as infection.
Is it possible to drink too much?
It’s rare for healthy people, but drinking very large amounts quickly can lower sodium levels in the blood. People with heart or kidney problems should follow their doctor’s advice. Our guide to how much water to drink a day explains the general guidance.
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
