Dealing with dehydration in the elderly

Written by Zenya Smith04/07/23


24 Hours of Care at Home

Risk factors in dehydration

Often, the first sign of dehydration is feeling thirsty. However, as we age, our thirst sensation may become weaker, meaning we may not realise that our bodies need more water. A loss of thirst is also common for those living with dementia or who have had a stroke.

Older people generally have a lower percentage of water in their bodies, which puts them at greater risk of dehydration, especially in hot weather.

Impaired renal function can also be a risk factor. As the kidneys age and their function slows, so does the hormonal response to dehydration. 

Some medications such as laxatives can exacerbate the likelihood of an elderly person becoming dehydrated. If an older person is experiencing incontinence, they may deliberately restrict their intake of fluids, as they are worried about “accidents”.


Dehydration and medication

Dehydration can change the effectiveness of certain medications, so being aware of the signs of dehydration can help prevent medical emergencies.

Many older people take warfarin to reduce blood clots. Dehydration can lead to lower levels of fluid in the blood, causing it to thicken, and may reduce the effectiveness of Warfarin.

Those who take Warfarin also need to have regular blood tests to ensure they are on the right dose. Dehydration may impact these results, making it more difficult to work out how much warfarin they really need.


Consequences of dehydration

If an older person becomes dehydrated, they are more likely to be hospitalised.  Even if they are only mildly dehydrated, they will likely feel tired and will have poorer concentration, memory problems and slower reaction times.

Other complications of dehydration include weakness, dizziness and therefore an increased risk of falls.

How to avoid dehydration


Recognising dehydration

Common signs of dehydration include a dry mouth, tongue and lips. You may also notice that the elderly person has sunken eyes and dry, papery skin. They may seem to be unusually drowsy, confused or disoriented too. They might also feel dizzy because their blood pressure is low, however, these signs are frequently seen in other conditions, so they might be due to another cause – it’s important to consult a medical professional if you’re concerned about these symptoms. 

An elderly person who is dehydrated will often have concentrated urine which can appear dark and have a strong odour, while normal urine should be pale in colour and be odourless.


A person who is dehydrated may experience cramping in the limbs, or feel generally unwell. They can become irritable and have difficulty sleeping. Symptoms of more severe dehydration include a weak, rapid pulse, faster than usual breathing, severe muscle cramps and contractions, and a bloated stomach.

Spotting heat stroke

If you’re caring for a loved one in hot weather – it’s important to frequently check they’re not suffering any of the following symptoms. These can all indicate heat stroke:

  • Headache
  • Dizziness and confusion
  • Loss of appetite and feeling sick.
  • Excessive sweating and pale, clammy skin.
  • Cramps in the arms, legs and stomach.
  • Fast breathing or pulse.
  • Temperature of 38C or above.
  • Being very thirsty.

Can dehydration cause blurred vision?

Blurred vision can be a sign of dehydration in the elderly, as the tear ducts can stop producing tears when there’s not enough water in the body. Tears are essential to keeping the eyes lubricated, comfortable and free from debris, so a lack of tears can easily lead to dry, irritated eyes and blurry vision.

Can dehydration cause headaches?

It’s estimated that the brain is three quarters water. As the control centre of all our bodily functions, feelings, and thoughts, preventing dehydration is crucial for keeping our brains working properly.

Fluid loss in the brain can cause it to temporarily shrink, pulling away from the skull and leading to a headache. If you or an elderly loved one experiences a sudden headache on a hot day, it could be a sign to drink more water.

The dehydration skin test

If you’re worried about a loved one who struggles to drink enough water, you may wonder if there’s an easy way to test and monitor hydration levels at home.

The easiest way to do this is with a simple skin test:

  1. Gently pinch the skin on the back of the hand, arm, or abdomen.
  2. Hydrated skin will spring back instantly.
  3. If the skin takes longer to bounce back, then dehydration is likely.


If you’re worried about dehydration, it’s always best to seek medical advice or call the NHS on 111.

Can dehydration cause high blood pressure?

Chronic, and regular bouts of dehydration in older adults have been linked to blood pressure changes, and may cause it to spike, or reduce. 

Dehydration can lead to a lower volume of blood in the body – which causes the overall blood pressure to reduce. 

While more research is needed into the impact of dehydration on high blood pressure, experts believe that when you lose too much fluid, the water content of the blood decreases, and sodium levels can increase to  high levels. To counteract this, the body releases a hormone called Vasopressin  that causes blood vessels to narrow – temporarily raising blood pressure.

Can dehydration cause a UTI?

When fluid is low, the body tries to store liquid in any way it can to ensure it has enough to keep functioning. One of the ways it does this is by preventing urination, however this can upset the concentration or balance of natural acids in urine, and lead to bacterial growth that causes urinary tract infections.

How can dehydration be prevented?

The most important strategy for preventing dehydration is to recognise when the person’s fluid intake is inadequate and ensure they drink more.

Residents in care homes may not drink enough because they are worried about not being able to get to the toilet in time, particularly if they need assistance. They may be physically unable to reach a drink when they need one too. 

Staff training on the importance of hydration, monitoring of fluid intake, assistance when necessary and the provision of the person’s preferred fluids are all important in care homes.

If your loved one receives elderly care at home, try to ensure they drink a minimum of five eight-ounce glasses of water or clear fluids each day. They should always have a drink accessible, and it is a good idea to monitor fluid intake.

They should be offered a variety of fluids, both hot and cold and given the assistance they need if they are unable to drink independently. Your loved one may find drinking easier with an aid such as a cup with a handle or lid, or by using a straw depending on their condition.

When they take their medication, offer a full glass of water to help them swallow it.

How to prevent dehydration


How to encourage someone to stay hydrated

It can be difficult to persuade your loved one to drink the amount of fluid they need, especially when they do not feel thirsty or they are worried about incontinence. You could try the following approaches:

  • Offer a choice of different drinks if they find water too tasteless or bland. They may like watered-down fruit juice, flavoured water or hot water with a slice of orange, lemon or lime. Low fat milk can also help replenish fluid and electrolytes (the electrically charged minerals that give the body energy) and is a tasty alternative to water.
  • Approach them positively offering a drink as an attractive option rather than as a necessity.
  • Offer drinks regularly and leave then accessible so that your loved one can take them little and often if they prefer.
  • Avoid too much caffeine or alcohol. While tea may be the nation’s favourite drink, it does still contain caffeine, which can have a diuretic effect and lead to the urge to urinate more frequently.  Switching to a decaffeinated variety is widely recommended.
  • Encourage them to increase their fluid intake in warmer weather.
  • Promote fluid intake more in the day than late at night if they have concerns about using the bathroom at night.
  • You can try to top up their fluid intake with certain foods too. Yogurt, soups, and cottage cheese are all high in water and can be part of a nourishing meal.

Quick tips – Staying hydrated in the heat

  • Drink plenty of liquid – you should aim to drink at least eight glasses of water per day. If you’re looking after a loved one with dementia, be sure to remind them or support them to take on fluids.
  • Understand your medication – there are certain prescriptions that may make it more likely for you to become dehydrated, especially in hot weather.
  • Eat lots of fruit and vegetables – many vegetables have a high water content, and also provide the nutritional value you need to stay healthy in the heat. Melon, cucumber and celery are handy to pack in a picnic if you plan to be outside in the sun.
  • Listen to your body – if you’re out in the sun, pay more attention than normal to what your body is telling you. Be alert to symptoms such as headaches, fatigue, nausea and lightheadedness.
  • Mix up your fluids – water is always the best way to hydrate, but it’s not the only way.  Glasses of squash and even a bowl of soup can help keep you hydrated.
This article is for informational purposes only and not to be taken as medical advice. For medical advice, always consult your GP.

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