Hydration and Cancer


During cancer treatment, it is very important that you stay hydrated. Water is needed for regulating your temperature and for removing wastes and toxins. The human body is made up of about 60% water. Every organ is dependent upon water for optimal functioning. Water and other fluids help you chew and swallow food to release the nutrients and often improves digestion. Even mild dehydration can cause some of the following symptoms: fatigue, dry mouth, lightheadedness, headaches, irritability, constipation and nausea. 

What does dehydration mean?

  • Dehydration is a condition caused by excessive loss of body fluids.  It occurs when your output of fluid exceeds fluid intake.
  • Infections, high fever, bleeding, or even something as simple as not drinking enough fluids can lead to dehydration.
  • Side effects of treatment such as vomiting or diarrhea can lead to dehydration.
  • Electrolytes, such as potassium and sodium, are present in the blood.  When these electrolytes are too high or too low, confusion, disorientation, and other symptoms can occur.

What are signs that I am not drinking enough?

  • Dry mouth
  • Dry skin
  • Dry eyes
  • Little or no urine output
  • Low blood pressure
  • Dark, strong-smelling urine
  • Fatigue
  • Skin that 'tents' when pinched
  • Fever  

Staying hydrated:

  • The “8 X 8 rule” is a good place to start.  Aim to drink 8, 8 ounce glasses of caffeine-free fluid a day. Drinks that contain caffeine contribute to fluid loss. If you develop a fever, diarrhea, or vomiting, you will need to increase your fluid intake to replace fluids. Drink 1 cup of fluid after each bout of vomiting or diarrhea.
  • Drink fluids throughout the day instead of waiting to drink when you feel thirsty. 
  • Keep a glass, cup, or bottle of water in sight at all times.  It is much more likely that you will drink fluids when they are within reach. 
  • Keep track of the fluids you drink to make sure you are getting enough fluids.
  • Everyone is unique. If you have edema (retaining fluid), other medical conditions (heart or kidney disease), or are receiving pallative care, your fluid goals may be less. Ask your healthcare provider for specific water goals per day.
  • Food contains some fluid. Only foods that are liquid at room temperature should be counted toward your goal of “8 X 8.” The following are foods and beverages that can be counted toward your fluid goal:

8 X 8 Goal Friendly Foods



soup and broth, gelatin, ice cream, fruit ice, popsicles, sorbets,watermellon, clear-liquid nutritional beverages  


water, milk, decaf coffee*,  decaf tea*, fruit or vegetable juice, decaf soda*, sports drinks, liquid nutrition supplements, hot chocolate, milkshakes, ice cubes, and ice chips


* Drinks that contain caffeine contribute to fluid loss. Use decaffeinated versions of these drinks instead.

What if I don’t like plain water?

Try sparkling waters, flavored waters, adding berries or slices of lemon, orgranes, cucumbers, or lime, or mixing water with a splash of 100% fruit juice or peppermint.

What if I have severe vomiting and can’t keep fluids down?

Try sucking on ice cubes and ice chips, and taking small sips of fluids frequently. This will be better tolerated than drinking large amounts at one time. If you are vomiting for 24 hours or more, contact your healthcare provider.