Cancer and Hydration

What is cancer?

Cancer, a genetic disease, is caused by changes in gene function1 which cause cells in the body to grow uncontrollably. With more than 100 types of cancer,1 this disease can start anywhere in the human body and variations are named for the tissues or organs where the cancer forms. 

The genetic changes that produce cancer are due to damage to DNA or errors in cell division, and this can be because of harmful chemicals or substances such as tobacco smoke. Though the body usually removes cells with damaged DNA, the ability to do this decreases as we age. This explains why older people have a higher risk of cancer.1 

Why is water essential for humans to function?

The consumption of adequate water each day is important for overall health, this is because the human body is made up of 60-75% water and almost all of the body’s major systems relies on water to function.2 Aloss of  only 4% of total body water can lead to dehydration3 which can further result in problems such as kidney stones, overheating, constipation, and mood changes.

Water is essential for human function as it:

  • Moistens tissues in the nose, mouth, and eyes
  • Regulates the temperature of the body
  • Dissolves the nutrients and minerals for the body to access
  • Transports oxygen and nutrients to cells
  • Lubricates joints
  • Flushes out waste products thus lessening the burden on the liver and kidneys
  • Protects tissues and organs

Dehydration is a cancer risk factor

Cancer and several of its therapies such as immunotherapy, cancer drugs (targeted) and chemotherapy can lead to getting insufficient fluids in the body. This dehydration can be caused by the following side effects:

  1. Vomiting
  2. Drains after surgery and tubes cause loss of fluids
  3. A loss of appetite
  4. Diarrhoea
  5. Sweating due to fever

These events, when severe, can lead to reduction in eating and drinking sufficiently. They can also cause increased loss of fluids, salts and electrolytes from the body that can't be replaced in time. The occurrence of this is called dehydration and symptoms include:

  1. Headaches
  2. Dizziness
  3. Increased body temperature
  4. Muscle cramps and weakness
  5. Increased thirstiness
  6. Dry skin, eyes and mouth
  7. Nausea
  8. Exhaustion
  9. Sunken eyes
  10. Lower urine output
  11. Weight loss
  12. Low blood pressure

Severe cases of dehydration associated with cancer can lead to confusion, organ failure, and coma. Dehydration associated with cancer can be resolved by drinking more fluids, not just water. This includes drinking juice, squash, smoothies, and tea. Milky beverages and soups also are beneficial and can offer some nutrition as well.

Doctors advise having 8 to 10 glasses of fluids a day4 and could suggest drinks that consist of electrolytes and salts to restore the lost fluids. They can also prescribe medications for the causes of dehydration, such as anti-sickness medicines. In advanced cases, water levels can be restored intravenously or through a drip into the bloodstream (if it is difficult to drink enough) which may involve a hospital stay. It is important to note the difficult nature in correcting dehydration when dealing with advanced cases of cancer. Ensuring hydration makes the side effects of cancer treatments less severe and greatly decreases the chances of delaying or missing cancer treatments. It also leads to less trips to the emergency room for IV hydration.5 

Bladder, renal and colon cancer

Bladder cancer is the abnormal growth of tissue (tumour) in the bladder lining, and can sometimes spread to the bladder muscle.7 Research has shown that people who do not drink enough water daily have an increased risk of developing bladder cancer,  and this is because hydration allows people to urinate more frequently which removes harmful substances out of the body.  These substances would otherwise possibly harm the bladder.6

Colon cancer is a disease that starts in the large intestine but affects the colon which is the last part of the digestive tract. This disease usually affects older people but can occur at any age. It generally commences as tiny, benign clusters of cells called polyps which form on the inside of the colon. This form of cancer is known to be lifestyle related with chronic dehydration being a key risk factor. This is because symptoms of colon cancer such as loose stool and diarrhoea lead to dehydration and those with this condition are advised to take note of their fluid intake.

Renal cancer, also known as kidney cancer, is the formation of cancer cells in tubules of the kidney. This condition is one of the most prevalent types of cancers and generally impacts people in their 60s and above.8  This form of cancer is impacted by dehydration which may cause a build-up of acids and waste products, clogging the kidneys with muscle proteins which further hurt the kidneys.9


The adequate consumption of water daily is vital for human function. This is because the human body is made up of 60-75% water, and bodily processes such as regulation of temperature and transportation of oxygen and nutrients to cells rely on hydration. Dehydration is a risk factor for cancer, a genetic disease caused by changes in gene function. Several cancer therapies e.g immunotherapy and chemotherapy reduce body fluid levels, hence doctors may prescribe medications such as anti-sickness medicines or IV drips to restore hydration. 


  1. What is cancer? - nci [Internet]. 2007 [cited 2022 Oct 3]. Available from:
  2. CDC. Water and healthier drinks [Internet]. Centers for Disease Control and Prevention. 2022 [cited 2022 Oct 3]. Available from:
  3. SITNFlash. Biological Roles of Water: Why is water necessary for life? [Internet]. Science in the News. 2019 [cited 2022 Oct 7]. Available from:
  4. Not enough fluid in your body (Dehydration) | Coping with cancer | Cancer Research UK [Internet]. [cited 2022 Oct 7]. Available from:,in%20your%20body%20(dehydration).
  5. Buckley MC. Cancer treatment side effect: Dehydration [Internet]. MD Anderson Cancer Center. [cited 2022 Oct 7]. Available from:
  6. Team E. Understanding risk factors for developing bladder cancer [Internet]. [cited 2022 Oct 7]. Available from:
  7. Bladder cancer [Internet]. 2018 [cited 2022 Oct 7]. Available from:
  8. Kidney cancer [Internet]. 2017 [cited 2022 Oct 7]. Available from:
  9. Can dehydration affect your kidneys? [Internet]. National Kidney Foundation. 2018 [cited 2022 Oct 7]. Available from:

Iqra Khalif

Pharmaceutical Science, University of Hertfordshire

Iqra Khalif is a pharmaceutical scientist with deep roots in research and development. She has a leadership qualification in global health and is interested in strategising for innovation in the life sciences.
She currently works in data analytics and management for a health-tech startup. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818