Staying hydrated during treatment

Drinking enough fluids is important during cancer treatment, especially if you have increased fluid losses from vomiting or diarrhoea. Not drinking enough can lead to dehydration. Dehydration occurs when the body doesn’t have enough water to carry out normal functions. Signs of dehydration can include less frequent urination or very dark urine, headaches, dizziness, dry mouth and low blood pressure ^1,2.

Tips to Stay Hydrated

• Aim for 8–10 glasses (about 1.8–2.3 litres) of fluids each day. This amount can vary depending on your height, weight and how much fluid you need to replace losses ^1,3.
• Measure how much your drinking glasses hold so you can track your intake. Many tall glasses hold more than one cup ¹.
• Keep a water bottle or beverages nearby at all times ¹.
• Set reminders around the house to drink regularly ¹.
• Make a simple chart with boxes and tick off a box for each cup of fluid you drink ¹.
• Thirst isn’t always a good indicator of dehydration, so drink based on your daily goal rather than waiting until you feel thirsty ².
• If you can’t drink large amounts at once, take small sips throughout the day ¹.
• Include foods with high fluid content such as ice blocks, jelly, Italian ice, soups, smoothies and watermelon ^1,3.
• Avoid alcoholic drinks and limit caffeinated beverages, as they can increase fluid loss ^1,3.
• Other beverage ideas include sparkling water, juices, sports drinks, broth, flavoured waters and oral nutrition supplements ^1,3.

References:

1. Cancer Council NSW. Hydration during cancer treatment [Internet]. Sydney: Cancer Council NSW; 2025 [cited 2025 Nov 18]. Available from: https://www.cancercouncil.com.au/cancer-information/living-well/nutrition-and-cancer/treatment-side-effects-and-nutrition/hydration/
2. eviQ. Dehydration and fluid intake during cancer treatment – Information for patients [Internet]. Sydney: Cancer Institute NSW; 2023 [cited 2025 Nov 18]. Available from: https://www.eviq.org.au/patients-and-carers/side-effects/dehydration
3. Queensland Health. Nutrition tips for staying hydrated [Internet]. Brisbane: Queensland Health; 2018 [cited 2025 Nov 18]. Available from: https://www.health.qld.gov.au/__data/assets/pdf_file/0026/154394/oncol_hydration.pdf