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Dehydration and Lack of Fluids
Your body needs fluid (water) to work as it should. When you don’t have enough, it is called dehydration and it can cause several unpleasant, or even dangerous, symptoms. Having the right amount of fluid for your body to work correctly is called being hydrated.
What causes dehydration?
You can become dehydrated because you don’t eat or drink enough or because you are losing too much fluid. People with cancer also can become dehydrated for many reasons such as:
- Nausea and vomiting
- Diarrhea
- Fever with or without an infection
- Bleeding
- Procedures and surgeries can cause fluid loss
- Trouble swallowing
Some people with cancer may be more likely to become dehydrated for other reasons:
- Age: Infants, children, and older adults are at a greater risk for dehydration.
- Chronic illness: People with diabetes, kidney disease, or who are taking medicines that make a person urinate more may have trouble taking in enough fluids.
- Exercise: People who exercise lose more fluids through sweat.
- Memory, thinking and focus changes (cognitive problems): People with cognitive problems are more likely to not take in enough fluids.
What are the symptoms of dehydration?
It’s not always easy to know if you are dehydrated. Here are some of the common symptoms of dehydration.
- Dry mouth and lips that make it hard to talk
- Thirst
- Dizziness or weakness
- A swollen, cracked, or dry tongue
- Dry skin or skin that “tents” (stays up) when lightly pinched
- Higher than normal body temperature with or without chills
- Headache
- Weight loss
- Dark urine (pee) or making less urine
- Sunken eyeballs
- Poor appetite and no thirst (Dehydrated people may feel less hungry and thirsty.)
If it is severe or untreated, dehydration can lead to low blood pressure, confusion, sleepiness, damage to the kidneys and liver, and even death.
Treating dehydration
For most people, dehydration can be prevented and treated by drinking more fluids. Your cancer care team might suggest an oral rehydration drink to help replace fluids, sugar, and electrolytes.
For people who can’t take in enough fluid by mouth, the cancer care team may order fluids given into a vein (IV fluids).
Your cancer care team will want to find out why you are dehydrated and treat that problem. This includes any symptoms or side effects that make it hard for you to get enough fluids. For example, nausea, vomiting, diarrhea, and trouble swallowing can make it harder to get or keep enough fluids in your body.
Tips for managing dehydration
Fluids are in both food and drink. So, if you aren’t eating enough, you need to drink more fluids to make up the difference. You can do many of the same things to prevent and treat dehydration.
- Drink small amounts of fluid often. Sometimes cold or iced fluids are easier to drink.
- Eat foods that have more fluid. Try to eat fruits, vegetables, soups, gelatins, popsicles, yogurt, and other moist foods. Smoothies also work well.
- Suck on ice chips or popsicles if you’re having trouble drinking or eating
- Drink more before you exercise and before you go outside in hot weather.
- Keep a small cooler with juice boxes, bottled water, or other drinks next to you, if it’s tiring to get up.
- Keep a food and fluid diary to keep track of how much fluid you’re getting each day.
- Avoid alcohol and caffeine which can worsen fluid loss
- Put balms or moisturizers on your lips to avoid painful cracking
Talk to your cancer care team if you
- Can’t drink or keep down liquids
- Have vomiting, diarrhea, fever, or trouble swallowing for more than 24 hours
- Have urine that’s very dark or is only a small amount, or if there’s no urine for 8 hours or more
Call 911 or go to the emergency room if the person who is dehydrated:
- Is dizzy, weak or faints when standing up
- Becomes confused or disoriented
- Has a seizure
- Has a fast heart rate
- Written by
- References
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
American Society of Clinical Oncology. Dehydration. Cancer.net. Accessed on February 16, 2024.
Bethancourt HJ, Kenney WL, Almeida DM, Rosinger AY. Cognitive performance in relation to hydration status and water intake among older adults, NHANES 2011-2014. Eur J Nutr. 2020;59(7):3133-3148.
Sterns RH. Etiology, clinical manifestations, and diagnosis of volume depletion in adults. In, UpToDate, Emmett M (Ed), UpToDate. Accessed at uptodate.com on February 16, 2024.
Sterns RH. Maintenance and replacement fluid therapy in adults. In, UpToDate, Emmett M (Ed), UpToDate. Accessed at uptodate.com on February 16, 2024.
Taylor K, Jones EB. Adult Dehydration. [Updated 2022 Oct 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Accessed at https://www.ncbi.nlm.nih.gov/books/NBK555956/ on April 3, 2024.
Last Revised: June 26, 2024
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