Symptom Management, Palliative Care, or Supportive Care to relieve side-effects is an important part of cancer care and treatment and should always form part of the overall treatment plan.

Dehydration occurs when an individual does not take in enough fluid or loses too much fluid. A baby’s body is made up of around 85% water, a toddler’s around 80%, a teenager’s around 75% and an adult’s body consists of around 70% water which drops to about 60% as they get older.

Every cell and organ in the human body depends on this water to grow and function optimally. For instance, although only 2% of body-weight, the brain requires 15% of the blood flow, and a shortage of water in the brain can manifest in feelings of anxiety, irritation, anger, short attention span, impatience and even depression.

The water in your body is spread around in constant percentages:

  • Human bones contain 31% water;
  • Kidneys contain around 79% water
  • Muscles are 79% water;
  • Our heart is around 73% water;
  • The human brain is 85% water; and
  • The skin is 64% water;

The water in your body performs the following essential functions:

  • Controls the heart rate and blood pressure
  • Creates saliva
  • Lubricates and protects the joints
  • Protects organs and tissue, including the eyes, ears, and heart
  • Regulates core body temperature
  • Removes waste and toxins
  • Transports nutrients and oxygen throughout the body via the blood

While we can survive a reasonably long time without food, the human body can only last about 3 days without water before it begins breaking down as various parts start to malfunction and top working.

Individuals having cancer treatment may be at a higher risk for dehydration due to various treatment side-effects which make them lose water, such as diarrhoea and vomiting.


Relieving side effects is an important part of total cancer care and treatment, which is why you should discuss any symptoms your child is experiencing, new symptoms as well as any changes in symptoms with their Oncology Team, so that they can work out a regimen of palliative or supportive care for them.

The longer one goes without taking in enough fluid, the more dehydrated one becomes. While most of us think that thirst is the only way that your body lets you know you need to drink water, there are actually many signs of dehydration, including:

  • A dry or sticky mouth or a swollen tongue
  • Allergies
  • Constipation
  • Dark yellow urine or a decrease in urination
  • Digestive problems
  • Dizziness or light-headedness
  • Dry skin
  • Fatigue or weakness
  • Headaches
  • Irritability
  • Nausea
  • Weight loss

Severe dehydration, which can be life-threatening and needs immediate medical treatment, can cause the following symptoms:

  • Extreme thirst
  • Fever
  • Rapid heartbeat
  • Lack of urination for more than eight hours
  • Sunken eyes
  • Inability to sweat
  • Inability to produce tears
  • Low blood pressure
  • Disorientation or confusion
  • Coma
  • Death

Dehydration does not only lower immune function, it can also shut down self-healing mechanisms, increase acidity, decrease oxygen uptake by red blood cells and suppress many enzymatic reactions vital to cellular function.


While the body does consist mainly of water, it cannot store water and loses it constantly throughout the day through natural body functions, such as breathing, sweating, and going to the toilet.

While around 20% of the daily water requirement can be replaced by drinking other fluids and eating water-rich fruit and vegetables, the majority of it should come from drinking pure water.

Certain conditions affect the body’s ability to stay hydrated, and require that one makes a more concerted effort to take in more fluids. Waiting until one is thirsty is not a good idea because by that time one is actually already around 3% dehydrated.

It takes only 1% dehydration inside your cells to cause a 10% loss of energy. This means that even mild dehydration (2% to 3%) causes 20% to 30% energy loss! This creates havoc (stress) at the cellular level, which causes toxic build up, suppresses the immune system, slows metabolism and causes or worsens many other health problems.

Causes of dehydration include:

  • Diarrhoea, Nausea, and Vomiting: Many of the treatments for cancer cause diarrhoea, nausea, and/or vomiting, which means that the body is losing a lot of fluid.
  • Fever: A high fever can result in dehydration. Children receiving cancer treatment may be at risk for developing infections that can cause a fever.
  • Medication: Some medications can cause a person to urinate or sweat more than normal, thereby losing fluids and the electrolytes contained in them which are minerals that help regulate the body
  • Environment: Living, working, and exercising in a hot or humid environment increases the need for fluids.
  • Exercise: Everyone loses water through sweat, and people who engage in physical activity generally produce a significant amount of sweat. Children who play outside lose a lot of water via sweating even if the sweat is not particularly visible.
  • Other factors: Women and overweight or obese individuals are at greater risk for dehydration.


A doctor may use different methods to diagnose dehydration, including:

  • Taking your child’s vital signs; temperature, blood pressure, and pulse.
  • Pressing on your child’s fingertips. Fingertips that do not return to pink after pressing can indicate dehydration.
  • Gently pinching the skin on the back of your child’s hand, arm, or other area. Skin that is slow to snap back can indicate dehydration.
  • Blood tests to examine factors such as your child’s electrolytes and kidney function
  • Checking the colour of your child’s urine; good hydration is signified by light-coloured urine – the darker the urine the more dehydrated one is (this is a quick and easy check you can do yourself with your child at home)


If your child is experiencing being dehydrated, the following may help to relieve the symptoms and get them back to being fully-hydrated again, especially if they are undergoing treatment and do not really have an appetite:

  • Let your child suck on ice chips or ice popsicles
  • Apply moisturiser to your child’s cracked lips and medication to your child’s mouth sores so that drinking and eating is less painful.
  • If your child is able to drink, give them small amounts of fluid frequently instead of a large amount at one time. Drinking too much at once may cause vomiting.
  • Keep a water bottle near your child at all times, and make sure they sip from it throughout the day.
  • Give your child a large glass of water before bed and when they wake up each morning to counteract all the hours that they are sleeping and not taking in liquids
  • If your child has diarrhoea, give them beverages that contain sodium and potassium to help replace these lost minerals.
  • If your child is fatigued, keep ice and drinks within their reach so they can access them easily

If your child is not vomiting or experiencing diarrhoea and is moderately dehydrated, their doctor may recommend they drink an oral rehydration solution.

Severe dehydration requires fluids to be given intravenously (through a vein).


Prevention is always better than cure, as the old saying goes, and there are various ways in which you can your child’s body- fluid balance in check:

Lots of Fluids: The amount of fluid required daily to stay hydrated depends on one’s health and lifestyle; give your child lots of water and other fluids to drink, including, juice, herbal tea, milkshakes, flavoured water,  and whatever else they can tolerate.

High Water Content Foods: While drinking water is the best hydration source, many foods contain water and can help replenish lost fluids. Choose foods like:

  • Cucumber and Lettuce (96% water)
  • Zucchini, Radish and Celery (95% water)
  • Tomatoes and Cabbage (93% water)
  • Watermelon, Strawberries, Cauliflower, Eggplant, Red Cabbage, Peppers and Spinach (92% water)
  • Broccoli (91% water)
  • Peaches (88% water)
  • Pineapple, Cranberries, Oranges, Raspberries and Carrots (87% water)
  • Apricots, Blueberries and Plums (85% water)
  • Apples and Pears (84% water)
  • Cherries and Grapes (81% water)
  • Bananas (81% water)

Soups, popsicles, and yoghurt also have high water content.

Manage Side Effects: If your child is having a cancer treatment that is causing nausea, vomiting, or diarrhoea, talk with their doctor about ways to prevent or minimise the side effects.