Q&A: How to Prevent, Detect, & Treat Dehydration in Aging Adults

Q: How can we get my older mother to drink more water? She is susceptible to urinary tract infections and seems to be often dehydrated no matter what we do. We were also wondering if coffee and tea are okay, or should they be avoided to reduce dehydration? And what are symptoms of dehydration in older women that we can look out for?

A: Dehydration is indeed an important problem for older adults. It can be common even when it’s not hot outside.

Helping an older person increase her fluid intake, as you’re trying to do, is one of the best ways to reduce the risk of dehydration.

Now how to actually do this? Studies — and practical experience — suggest that the best approaches include:

1. Frequently offering the older person a drink, preferably on a schedule,
2. Offering beverages the person seems to prefer,
3. Not expecting older adults to drink a large quantity at a single sitting,
4. Addressing any urinary incontinence issues that might be making the person reluctant to drink often.

But your question brings up other issues in my mind. Has frequent dehydration been confirmed? (Dehydration can be hard to correctly diagnose.) Have you been able to measure how much your mother drinks, and how does this amount compare to the recommended daily fluid intake for older adults?

Also, is the real goal to prevent or manage frequent urinary tract infections, and is increasing her hydration likely to achieve this?

So let’s review the basics of dehydration in older adults, the symptoms of dehydration in elders, and what’s known about helping older adults stay hydrated. I will then share some additional tips on helping your mother maintain hydration.

The Basics of Dehydration

What is dehydration and what causes it?

Dehydration means the body doesn’t have as much fluid within the cells and blood vessels as it should.

Normally, the body constantly gains fluid through what we eat and drink, and loses fluid through urination, sweating, and other bodily functions. But if we keep losing more fluid than we take in, we can become dehydrated.

If a person starts to become dehydrated, the body is designed to signal thirst to the brain. The kidneys are also supposed to start concentrating the urine, so that less water is lost that way.

Why are older adults at higher risk for dehydration?

Unfortunately, the body’s mechanisms meant to protect us from dehydration work less well as we age. Older adults have reduced thirst signals and also become less able to concentrate their urine.

Other factors that put older adults at risk include:

• Chronic problems with urinary continence, which can make older adults reluctant to drink a lot of fluids
• Memory problems, which can cause older adults to forget to drink enough, or forget to ask others for something to drink
• Mobility problems, which can make it harder for older adults to get something to drink
• Living in nursing homes, because access to fluids often depends on the availability and attentiveness of staff
• Swallowing difficulties

Dehydration can also be brought on by an acute illness or other event. Vomiting, diarrhea, fever, and infection are all problems that can cause people to lose a lot of fluid and become dehydrated.

COVID-19 has also been linked to dehydration in older adults (although it’s hard to say whether that’s because the virus itself dehydrates them versus people drinking less when they are weak and sick). And of course, hot weather always increases the risk of dehydration.

Last but not least, older adults are more likely to be taking medications that increase the risk of dehydration, such as diuretic medications, which are often prescribed to treat high blood pressure or heart failure. (Diuretics are also sometimes prescribed for leg swelling due to aging veins, but research shows they don’t work well for this purpose. Learn more here: Leg Swelling in Aging: What to Know & What to Do.)

A UK study of older adults in residential care found that 46% had impending or current dehydration, as diagnosed by blood tests.

How is dehydration diagnosed?

For frail older adults, a simple preliminary check, if you’re concerned about dehydration, is to get the older person to drink some fluids and see if they perk up or improve noticeably. (This often happens within 5-10 minutes.)

This is not a clinically-proven method, but it’s easy to try. If drinking some fluids does noticeably improve things, that does suggest that the older person was mildly dehydrated.

For a truly accurate diagnosis in older adults, the most accurate way to diagnose dehydration is through laboratory testing of the blood. Dehydration generally causes abnormal laboratory results such as:

• Elevated plasma serum osmolality: this measurement relates to how concentrated certain particles are in the blood plasma
• Elevated creatinine and blood urea nitrogen: these tests relate to kidney function
• Electrolyte imbalances, such as abnormal levels of blood sodium
• Low urine sodium concentration (unless the person is on diuretics)

(Doctors often sub-classify dehydration based on whether blood sodium levels are high, normal, or low.)

Dehydration can also cause increased concentration of the urine — this is measured as the “specific gravity” on a dipstick urine test. However, this is not an accurate way to test for dehydration in older adults, since we tend to lose the ability to concentrate urine as we get older. This was confirmed by a 2016 study, which found that the diagnostic accuracy of urine dehydration tests in older adults is “too low to be useful.“

What are the symptoms of dehydration in elders?

There are also a number of physical symptoms associated with dehydration. However, a 2015 study of older adults found that the presence or absence of dehydration symptoms is not an accurate way to diagnose dehydration.

Physical symptoms of dehydration may include:

• dry mouth and/or dry skin in the armpit
• high heartrate (usually over 100 beats per minute)
• low systolic blood pressure
• dizziness
• weakness
• delirium (new or worse-than-usual confusion)
• sunken eyes
• less frequent urination
• dark-colored urine

Symptoms of dehydration in women are generally the same as in men.

But as noted above: the presence or absence of these physical signs are not reliable ways to detect dehydration. Furthermore, the physical symptoms above can easily be caused by health problems other than dehydration.

This study published in 2019 confirmed that commonly used symptoms do not accurately detect dehydration in frail older adults: Signs and Symptoms of Low-Intake Dehydration Do Not Work in Older Care Home Residents—DRIE Diagnostic Accuracy Study.

In 2020, a European group working on diagnosing dehydration in nursing home residents proposed a diagnostic approach that is summarized here. It involves a combination of medical history, physical signs, and laboratory testing.

In short, there is no easy simple way to confirm (or rule out) dehydration in an older person.

So if you are concerned about clinically significant dehydration — or about the symptoms above — blood tests results may be needed. A medical evaluation for possible dehydration should also include an interview and a physical examination.

What are the consequences of dehydration?

The consequences depend on how severe the dehydration is, and perhaps also on how long the dehydration has been going on.

In the short-term, dehydration can cause the physical symptoms listed above. Especially in older adults, weakness and dizziness can provoke falls. And in people with Alzheimer’s or other forms of dementia, even mild dehydration can cause noticeable worsening in confusion or thinking skills.

Dehydration also often causes the kidneys to work less well, and in severe cases may even cause acute kidney failure.

The consequences of frequent mild dehydration — meaning dehydration that would show up as abnormal laboratory tests but otherwise doesn’t cause obvious symptoms — are less clear.

Chronic mild dehydration can make constipation worse. Otherwise, a 2012 review found that the only health problem that has been consistently associated with low daily water intake is kidney stones.

A 2013 review on fluid intake and urinary system diseases concluded that it’s plausible that dehydration increases the risk of urinary tract infections, but not definitely proven.

A 2020 review on the effect of increasing fluid intake to prevent UTIs also noted that “Patients with UTI are often advised by clinicians to keep adequately hydrated or drink more fluids. However, the evidence base for this recommendation remains unclear.”

Speaking of urinary tract infections (UTIs), if you are concerned about frequent bacteria in the urine, you should make sure this reflects real UTIs and not simply a sign of the older person’s bladder being colonized with bacteria.

This is a very common condition known as asymptomatic bacteriuria, and incorrectly diagnosing this as a UTI can lead to pointless overtreatment with antibiotics. (More on this issue below, or see Q&A: Why Urine Bacteria Doesn’t Mean a UTI Needs Antibiotics.)

How is dehydration treated?

The treatment of dehydration depends on:

• Whether the dehydration appears to be mild, moderate, or severe
• What type of electrolyte imbalances (such as high/low levels of sodium and potassium) appear on laboratory testing
• If known, the cause of the dehydration

Mild dehydration can usually be treated by having the person take more fluids by mouth. Generally, it’s best to have the person drink something with some electrolytes, such as a commercial rehydration solution, a sports drink, juice, or even bouillon. But in most cases, even drinking water or tea will help.

Mildly dehydrated older adults will often perk up noticeably after they drink some fluids, usually within 5-10 minutes.

Moderate dehydration is often treated with intravenous hydration in urgent care, the emergency room, or even the hospital. Some nursing homes can also treat dehydration with a subcutaneous infusion, which means providing fluid through a small IV needle placed into the skin of the belly or thigh. This is called hypodermoclysis, and this is actually safer and more comfortable for older adults than traditional IV hydration.

Severe dehydration may require additional intervention to support the kidneys, and sometimes even requires short-term dialysis.

How to prevent dehydration in older adults?

Experts generally recommend that older adults consume at least 1.7 liters of fluid per 24 hours. This corresponds to 57.5 fluid ounces, or 7.1 cups.

What are the best fluids to prevent dehydration?

I’m unaware of any research or guidelines clarifying which fluids are best to drink. This is probably because clinical research hasn’t compared different fluids to each other.

As to whether certain fluids are dehydrating: probably the main fluid to be concerned about in this respect is alcohol, which exerts a definite diuretic effect on people.

The effect of caffeine on causing people to lose excess water is debatable. Technically caffeine is a weak diuretic. But real-world studies suggest that people who are used to drinking coffee don’t experience much diuretic effect.

Now, caffeine may worsen overactive bladder symptoms, so there may be other reasons to be careful about fluids containing caffeine. But as best I can tell, coffee and tea are not proven to be particularly dehydrating in people who drink them regularly.

The safest approach would still be to drink decaffeinated drinks. But if an older person particularly loves her morning cup of (caffeinated) coffee, I’d say to consider accommodating her if at all possible.

How to help older adults to stay hydrated?

A 2015 review of nursing home interventions intended to reduce dehydration risk concluded that “the efficacy of many strategies remains unproven.” Still, here are some approaches that are reasonable to try:

• Offer fluids often throughout the day; consider doing so on a schedule.
• Offer smaller quantities of fluid more often; older adults may be reluctant to drink larger quantities less often.
• Be sure to provide a beverage that is appealing to the older person.
• See if the older person seems to prefer drinking through a straw.
• Supplement fluids with water-rich fruit (e.g. watermelon) or other foods with high water content.
• Identify any continence concerns that may be making the older person reluctant to drink. Keeping a log of urination and incontinence episodes can help.
• Consider a timed toileting approach, which means helping the older person get to the bathroom on a regular schedule. This can be very helpful for people with memory problems or mobility difficulties.
• Track your efforts in a journal. You’ll want to track how much the person is drinking; be sure to note when you try something new to improve fluid intake.
• Offer extra fluids when it’s hot, or when the person is ill.

Practical tips for family caregivers

Let’s now return to the issues brought up in the question.

Family caregivers are often concerned about whether an older person is drinking enough. Since dehydration is indeed very common among older adults, this concern if very important.

However, before expending a lot of energy trying to get your mother to drink more, I would encourage you to consider these four suggestions:

1.Measure how much your mother is actually drinking most days.

This can require a little extra effort. But it’s very helpful to get at least an estimate of how much the person drinks. This can confirm a family’s — or doctor’s — hunch that the person isn’t taking in enough fluid, and can help the care team figure out how much more fluid is required.

Again, the recommendation for older adults is to consume at least 1.7 liters/day, which corresponds to at least 57.5 fluid ounces. In the US, where a measuring cup = 8 ounces, this is equivalent to 7.1 cups/day.

Keep a journal to record how much fluid your older parent is drinking. It’s generally important to track anything you want to improve.

2. Confirm that your mother is, in fact, often dehydrated.

As noted above in the section on diagnosing dehydration: physical symptoms and urine tests are not enough to either diagnose dehydration or rule it out.

Instead, consider these two approaches to confirming clinical dehydration. One is to see if her energy and mental state perk up when she drinks more. The other is to talk to the doctor and request blood tests to confirm dehydration.

Now, you don’t necessarily want to request blood tests every time you suspect mild dehydration. But especially if your mother’s dehydration has never been confirmed by a serum osmolality test, it might be useful to do this at least once.

3. If frequent urinary tract infections (UTIs) are a concern, learn about asymptomatic bacteriuria and try to determine whether these are real UTIs versus a colonized bladder.

Sometimes I’ve seen families hellbent on increasing hydration or taking other measures, because they are concerned about repeated or persisting urinary tract infections (UTIs).

But UTIs are a bit like dehydration. A UTI is a common problem in older adults and is potentially very serious. But it’s also easily misdiagnosed, even by professionals.

Sometimes, when an older person keeps being diagnosed with a UTI repeatedly, the problem is actually that the older person has asymptomatic bacteriuria. This is a very common condition in which an older person’s bladder becomes colonized with bacteria. It probably happens because people’s immune systems get weaker as they age.

So how is this different from a UTI? Both conditions will cause a positive urine culture, meaning that bacteria is in the urine. The main difference is that in asymptomatic bacteriuria, the older person doesn’t experience pain, inflammation, increased confusion, or other symptoms of infection.

In a young person, bacteria in the urine is very uncommon and almost always corresponds to a clinically significant infection. But in an older person, bacteria in the urine is common.

So you cannot diagnose a UTI in an older person just on the basis of a positive urine culture. Instead, the family and clinician must note other signs of infection, such as pain or delirium.

Families are often surprised to learn that clinical trials have repeatedly found that it is not helpful to treat asymptomatic bacteriuria, but it’s true. In fact, a 2015 study found that treating asymptomatic bacteriuria with antibiotics increased the likelihood of later having a real UTI, and that the real UTI was more likely to be antibiotic-resistant.

For more on this topic, see Q&A: Why Urine Bacteria Doesn’t Mean a UTI Needs Antibiotics.

4. Talk to your mother to get her perspective on drinking more (and to find out if continence issues are a concern for her).

Before you keep pressuring her to drink more: have you spent some time talking to her to learn more about her perspective on drinking more, and on avoiding dehydration?

The more we learn about how an older person sees a situation, the better equipped we are to try to assist them.

In particular, inquiring about how an older adult feels about drinking sometimes reveals that they are concerned about worsening their urinary continence symptoms. (Learn more about managing these here: Urinary Incontinence in Aging: What to know when you can’t wait to go.)

5. Pay attention to figure out which fluids your mother prefers to drink and try scheduling frequent small drinks.

Ultimately, there’s no substitute for paying close attention, keeping track of your observations, and doing some trial and error to figure out what seems to improve things.

No doctor has a magic formula to get an older person to drink more. So, identify the drinks your mother prefers, start tracking how much she drinks, and then start experimenting to figure out what works.

Usually, a combination of the following three approaches will improve fluid intake:

• Offer a beverage the person likes,
• Offer small-to-moderate quantities of the beverage on schedule,
• Address any urinary incontinence concerns.

You can also increase fluid intake by offering foods that contain a lot of water, such as watermelon, or perhaps soups.

Good luck!

This article was last reviewed in June 2024.