Author: Karen Arnold-Korzeniowski, MSN RN
Last Reviewed: June 29, 2023

Dehydration is when there is not enough fluid in your body. Dehydration can be mild or very serious. Hydration is important because water makes up about 66% of your body and helps it work correctly.

When you are properly hydrated, it helps:

  • Balance minerals and electrolytes in your body which can affect how your organs work.
  • Lubricate your joints and eyes so they can move and work more easily.
  • Keep your body at a healthy temperature.
  • You digest the food you eat.
  • Remove waste and toxins from your body.
  • Your skin look and stay healthy.

What causes dehydration?

Dehydration is caused by not drinking enough or losing more fluid than what you are taking in. Fluid is lost from your body in many ways, such as sweating, crying, throwing up, having diarrhea, and through your urine.

Treatments for cancer and the cancer itself can cause side effects that lead to dehydration. These side effects are loss of appetite, changes in how you swallow, nausea and vomiting, diarrhea, fevers, and fatigue.

What are the symptoms of dehydration?

When you are dehydrated, you will feel thirsty and have a dry mouth. You may also feel light-headed, have a headache, feel more tired than normal, have dark-colored/bad-smelling urine, your skin may be dry, or you may start to urinate less often than normal.

Signs of more serious dehydration that you need to tell your provider about right away are:

  • Feeling confused,
  • Fainting or feeling dizzy.
  • Low blood pressure.
  • Not urinating at all.
  • Breathing faster than normal.
  • Fast heart rate.

How is dehydration diagnosed?

Your provider can ask you questions and do a skin turgor test to see if you are dehydrated. A provider may pinch the skin on your hand or other part of your body. If your skin takes longer than it should to return to normal it can mean you are dehydrated. More specific ways to see if you are dehydrated and what effects it is having on your body can be to test your blood and urine.

How is it treated?

Treatment for dehydration depends on what is causing it and how severe it is. Talk to your provider about how much fluid you should drink in a day as this is different for each person. Ways that dehydration is treated are:

  • If you are able, drink plenty of fluids. Water is always best and try to drink less caffeinated and sugary drinks. Any foods that melt at room temperature can also be considered fluids. Fruits and vegetables also contain water. In some cases, you may need fluids that have electrolytes. Ask your provider what is best for you.
  • Loss of appetite can make it hard to get enough fluids in. You can try flavoring water with a splash of fruit juice or lemon. Eat foods that are mostly liquid like soup and water ice.
  • A speech and language pathologist can do tests to see how you are swallowing and can give you ways to manage these issues and prevent dehydration.
  • If you have nausea and/or vomiting, you may be able to take medication or change your diet to help this side effect. Medications and diet changes can also be used to help manage diarrhea. It can be helpful to track what foods make your side effects worse. Taking small, frequent sips of water can be helpful. Make sure you have water close by to drink while you are feeling better.
  • Fatigue can affect your ability to do everyday tasks. Try to have someone help you with these until you feel better. Having help with these tasks will help you to save energy for things like making sure you are taking in enough fluids.
  • If your dehydration is affecting the way your body works or if you are unable to take in enough fluids, you may need intravenous (IV, into a vein) fluids. Your provider will determine what type and how much fluids you need. This can be given in an outpatient or inpatient setting.

Hydration is an important part of your health. If you are feeling dehydrated during your cancer treatment, talk to your provider or dietitian about how you can stay hydrated.

NHS Inform. Dehydration. 2023.

Reber, E. et al. 2019. Management of Dehydration in Patients Suffering Swallowing Difficulties. Journal of Clinical Medicine.

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