Dehydration in Seniors: Why It’s Different and What You Need to Know

Why staying properly hydrated is especially critical for seniors

Author: Ernest Mandel, M.D.
Two seniors sitting at a meal and holding glasses of water

Dehydration is a common yet often underestimated health concern that affects individuals of all ages. However, in seniors, its impact can be particularly severe and complicated. The aging process brings about physiological changes that make older adults more vulnerable to the effects of dehydration, which can lead to serious health consequences. Learn more about the unique aspects of dehydration in seniors, including why they are at increased risk, signs to watch out for, and practical strategies to prevent this potentially dangerous condition.

What is dehydration?

Dehydration happens when the body loses more fluids than it takes in. This can disrupt the balance of electrolytes or lead to reduced blood volume, which can quickly lead to health issues, even serious ones. Water and electrolytes are crucial for many bodily functions, including regulating body temperature, transporting nutrients, eliminating waste, and maintaining proper organ function. Additionally, low blood volume can lead to low blood pressure and decreased delivery of oxygen and nutrients to critical organs such as the brain or the kidneys. 

Signs of dehydration include:

  • Thirst
  • Fatigue
  • Light headedness
  • Dizziness
  • Dark urine or inability to urinate

In severe cases, symptoms include:

  • Confusion
  • Difficult or fast breathing
  • Excessive sweating
  • Losing consciousness
  • Low blood pressure
  • Low temperature
  • Pale skin tone or a blue tone to the skin and lips

Anyone experiencing symptoms of severe dehydration should immediately seek medical attention.

Top reasons older adults are at risk for, and from, dehydration

  • As people age, their sensation of, and response to, thirst often becomes blunted, either due to normal age-related changes in the bodily processes that govern thirst and fluid intake or due to behavioral and cognitive changes that cause them to miss the brain’s signals to drink. Individuals with conditions like Alzheimer’s or cognitive decline are especially susceptible to missing these cues.
  • The hormone that tells your brain you’re thirsty also tells your kidneys to hold on to water to prevent becoming dehydrated. As people age, their kidneys’ ability to hold on to water diminishes. Further, some common medications taken by older adults can interrupt the kidneys’ ability to hold on to water, such as diuretics (medications that increase urination).
  • Older adults are particularly at risk for falls due to changes in functional status and mobility. Dehydration increases the risk of falls because it can cause people to become woozy or lightheaded.
  • Certain medical conditions that are more prevalent in older adults can also increase risk from dehydration, including diabetes, atrial fibrillation, and underlying kidney disease. 
  • Severe dehydration and the associated electrolyte changes and low blood pressure can exacerbate underlying medical conditions, like atrial fibrillation, or lead to end-organ damage, like kidney injury. 
  • Some medications for these underlying conditions, such as blood-pressure lowering medications, can increase this risk in older adults, as can medications that increase the kidneys’ susceptibility to damage from dehydration, such as ibuprofen, ace inhibitors, or angiotensin receptor blockers.

I worry most about the fall risk. For example, I worry about an older patient who is taking diuretics and sits at the beach all day sweating without properly rehydrating. That person is at risk of becoming lightheaded and falling, especially if they are also on other medications for blood pressure. If they have some underlying kidney disease, the dehydration and associated low blood pressure could also lead to acute kidney injury. 

How much fluid intake is enough?

For most healthy people with no medical conditions, 72 ounces of water per day should be adequate. In some cases though, like chronic heart failure or certain electrolyte disturbances like hyponatremia, which occurs when the concentration of sodium in the blood is too low, too much fluid intake can also be dangerous. There are many conditions that can affect this and you should check with your health care provider to find out if you need more or less.  

Why electrolytes are important and how you can maintain them

In addition to water, our blood contains electrolytes, which are minerals like sodium, calcium, and potassium that are vital to many key functions in the body, including keeping us hydrated. If we become dehydrated, we need electrolytes as well as water. 

Water alone does not contain enough salt and other minerals to replenish your body’s electrolyte balance if you have become dehydrated. That’s why it’s important to eat as well as drink to promote adequate hydration. For example, when I give blood, I eat a bag of pretzels and drink water to replace the electrolytes lost through the donated blood. Most of us can get the electrolytes we need by eating a nutritious diet.

Electrolyte drinks

Many people think sports drinks are a better source of fluids for hydration than plain drinking water because they include added sugar and salt designed to replenish electrolytes and to help your body absorb fluids.  While that’s true to a certain extent, they may not adequately replace the electrolytes your body needs and they often contain too much sugar. It really is best to eat a balanced diet and drink water. 

Tips to prevent dehydration

For healthy people of any age there are simple steps you can take to prevent dehydration.

  • Drink fluids throughout the day – 72 ounces is a good goal for most people. 
  • Drink if you feel thirsty, which is your body’s way of telling you you’re becoming dehydrated.
  • Eat regular meals and light snacks throughout the day to replace electrolytes lost through sweat and other processes.
  • Limit alcohol, which is a diuretic and does not contribute electrolytes or protein the body needs.
  • Talk with your health care provider about how much fluid intake is right for you. If you are on certain blood pressure medications or diuretics, dehydration can pose a threat. 
  • Make sure to compensate with food as well as fluids if you’re sick, whether you have a fever or not. It is a mistake to think fluids are enough when you’re sick. The same is true if you’re working or exercising outside in the heat and sweating. 

Staying hydrated is important at any age, but it takes a little more vigilance for older adults. I encourage you to make smart choices like eating a balanced diet and adjusting fluid intake with a health care provider’s guidance to keep dehydration at bay. 

Learn More

The Best Health Care for Seniors

Hebrew SeniorLife is the only senior health care organization affiliated with Harvard Medical School. Members of our caregiving teams specialize in providing geriatric care, and they do so with care and compassion.

A female doctor leans in to talk to a woman
Profile photo for Ernest Mandel

About Ernest Mandel, M.D.

Executive Vice President of Health Care, Hebrew SeniorLife

Biography Ernest Mandel, M.D., S.M. is the executive vice president of health care at Hebrew SeniorLife, where he oversees all HSL health care operations, including Hebrew Rehabilitation Center in both Roslindale and Dedham, and home and community-based services. He also...

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