“Water is the driving force of all nature,” Leonardo da Vinci once said. Earth is 70 percent water; our bodies are 60 percent. And just as water gives life to our planet, it is a driving life force in the human body. Water transports nutrients and oxygen, protects our organs and lubricates our joints. It also helps regulate heart rate, blood pressure and body temperature.
As important as it is to stay hydrated when you’re well, studies show it’s essential during cancer treatment. “Good hydration helps flush toxins out of the body and reduce treatment side effects, such as nausea, weakness, constipation and fatigue,” says Melissa Picchietti, RD, LDN, a Clinical Oncology Dietitian at Cancer Treatment Centers of America® (CTCA) in Chicago.
However, maintaining hydration may be a challenge for patients who are unable to consume enough fluid or who lose too much due to the symptoms of the disease or side effects of treatment. Chemotherapy and radiation therapy may cause fever or gastrointestinal (GI) distress, such as nausea, vomiting and diarrhea. Loss of appetite and changes to the way things taste are also common, which may affect how much you eat and drink, contributing to dehydration.
Certain medications may also play a role. For example, diuretics prescribed to treat high blood pressure and several chemotherapy drugs are designed to increase urination, so taking them may put you at increased risk.
“One of the keys for cancer patients is understanding that you have to replace fluids that are lost,” says Picchietti. “Even without treatment side effects, your body is constantly losing water as you breathe, sweat, urinate and defecate.”
Severe dehydration may require hospitalization and treatment with IV fluids and electrolytes to restore the body’s fluid balance. But even mild dehydration may disrupt your cancer treatment plan, since some drugs can only be safely given if your body is adequately hydrated.
Spotting signs of dehydration
Patients and their caregivers should recognize the signs and symptoms of dehydration in adults, including:
| Mild | Moderate | Severe |
|---|---|---|
| Fatigue or exhaustion | Dark yellow urine | Nausea and vomiting |
| Weakness or light-headedness | Decrease in urination | Extreme thirst |
| Dizziness or feeling faint | Dry skin and lips | Unable to sweat |
| Constipation | Headaches | Disorientation or confusion |
| Rapid heartbeat | ||
| Low blood pressure |
If you or a loved one is experiencing one or more signs of dehydration, despite drinking fluids, you should contact your primary care doctor.
How much water do you need?
Each person has unique hydration needs based on variables that include age, gender, weight and the specific treatment plan. A rule of thumb is to aim for at least 64 ounces a day, or eight cups. For a more personalized goal, divide your weight by two to determine how many ounces of fluid to aim for in a day. To translate your daily goal into cups, divide the number of ounces by eight. (Example: body weight: 150 lbs. /2 = 75 oz; 75/8 = 9.38 cups)
As long as your tap water is safe to drink, there’s no need to buy bottled water. Bottled water is not always better quality. It also costs more, wastes energy and puts millions of empty bottles into the garbage.
Mix it up to stay motivated
If you can’t tolerate the taste of water—it may have a metallic taste if you’re receiving chemotherapy treatment–there are many ways to enhance the flavor. Try adding fresh ginger, cinnamon, mint, cucumber or citrus slices, berries or a splash of fruit juice to give your water subtle flavor. You can also mix up your routine with a variety of beverages.
Sparkling water, smoothies, juices, milk, tea and even coffee count toward your daily fluid goal. It’s important to limit caffeine, which may increase urination and loss of sodium, making it more difficult to keep your body hydrated. Alcohol also is actually dehydrating and should be avoided.
Add electrolytes to your hydration plan
Beverages with electrolytes may be helpful to patients struggling with side effects, such as vomiting, diarrhea, hot flashes/excessive sweating and/or fever. Electrolytes are minerals, including sodium, chloride, potassium, magnesium and calcium, that are critical in maintaining key body functions. While many sports drinks are supplemented with electrolytes, watch the sugar content of these flavored beverages.
Healthier options that also contain electrolytes include coconut water and bottled water with added electrolytes. Some foods, like citrus fruit, are also rich in electrolytes. Speak with your dietitian to discuss which foods high in water and electrolytes might be worth adding to your nutrition plan.
Tips for staying hydrated
Start when you wake up. Your body needs rehydrating after 6-8 hours of sleep, so keep a glass of water on your nightstand.
Keep a reusable water bottle with you. This makes it easier to drink sips throughout the day instead of trying to chug large amounts before bedtime, which can disrupt sleep.
Fill a pitcher with your daily consumption. Keep it in your fridge or near your workspace as a reminder.
Create a water routine. Develop a schedule of times during the day to refill so you can hold yourself accountable. Use your phone’s alarm clock to set reminders.
Track your progress on an app. There are lots of free options to help you stick to a hydration plan.
Use a filtered water pitcher or faucet filter. Filters may improve the taste of tap water by reducing chlorine and other minerals.
Learn more about taking care of your skin and nails during cancer treatment.
