Managing side effects with nutrition

It's never easy handling side effects of treatment, but looking after your nutrition can help make things easier.

How to manage side effects with nutrition

Nutrition and you

It’s important to have good nutrition when going through cancer treatment. Treatment can sometimes take a toll on your body so having good nutrition can help support your body during this time.

We have put together some helpful guides to support you with your nutrition needs based on some very common side effects people experience during cancer treatment.

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If you still find it difficult to manage your side effects during treatment, please contact us for further guidance and support.

Managing a sore mouth and throat

What causes a sore mouth and throat during treatment?

Sometimes you can experience a sore mouth whilst on cancer treatment or due to the cancer itself. This can make swallowing and eating difficult which can be unpleasant and difficult to cope with. You may find you have to clear your throat after each mouthful or find yourself coughing more often. You may also experience a dry mouth post-chemotherapy or radiotherapy and find your saliva becomes thick and difficult to swallow.

Cancers in the head and neck area may cause you to have swallowing difficulties. Treatments to this area, such as radiotherapy can also cause you to experience a sore mouth and throat. Occasionally, you might find it harder to swallow or may cough after swallowing. If you are coughing or finding it difficult to swallow then please tell your clinician.

It may be a good idea to change to a soft diet during this time if you are having problems eating and swallowing whilst having chemotherapy.

What to eat with a sore mouth and throat

You may need to temporarily change your diet to include foods that are softer and easier to digest. Spicy, acidic, hard and crispy foods can make you feel worse so try to avoid these if you have a sore mouth and throat.  As your symptoms settle you should be able to reintroduce these foods into your diet. Here are some soft meal and food options that may help a sore mouth and throat:

Tips for oral hygiene when your mouth feels sore

It’s important to maintain oral hygiene and clean your teeth and gums regularly. Here are some helpful tips on how to keep your mouth clean:

  • Use a mouth rinse after each meal and at bedtime to keep bacteria from growing. To make this, mix one teaspoon of salt and one teaspoon of baking soda into one litre of water
  • Clean your teeth and gums thoroughly with a soft toothbrush after meals 
  • If you wear dentures, clean them daily and remove them whenever possible. If your dentures are loose-fitting, they can irritate the mouth and gums more

How to cope with a dry mouth and thick saliva

Having a dry mouth can be uncomfortable and make it more difficult to eat, speak and sleep. There’s no single way to treat a dry mouth, but here are some dry mouth remedies and tips you can follow:

  • Keep fresh water nearby and take sips throughout the day. Try and aim for at least eight to 10 cups a day
  • Carry a lip balm for times when your lips feel dry
  • Rinse your mouth with a warm salt solution before and after meals. Mix one teaspoon of salt with 900ml of boiled water and wait for it to cool down before rinsing
  • Use mouthwashes or sprays designed to help relieve dry mouth such as Bioxtra, Biotene or Oralieve. You can speak to a doctor to get them on prescription or you can buy them over-the-counter at your local pharmacy
  • Add extra moisture and sauces to your food, especially to dry foods such as bread, crackers and biscuits
  • Try to avoid foods that can irritate your mouth including spicy, crumbly, crunchy and citrus foods
  • Suck on ice cubes or ice lollies
  • Avoid drinking alcohol and smoking as these dry out your mouth even more
  • Avoid mouthwashes that contain alcohol


Good oral hygiene is important if you’re experiencing these side effects. This is because saliva is vital for keeping your teeth healthy and avoiding decay. Continue to see your dentist for regular check ups.

Side effects such as a sore mouth and throat can be difficult to cope with. At GenesisCare, we’re here to help and support you throughout your cancer journey, so please get in touch if you have any questions or concerns about the side effects you’re experiencing, your nutrition and cancer treatment.

Managing constipation, bloating and gas

About constipation

Constipation is when you find it harder to have a bowel movement or have them less often. You may find you don’t have a bowel movement for a few days at a time. You should talk to your doctor or nurse if you experience any of these symptoms. Sorting out the problem as soon as possible makes it easier to manage.

Common constipation symptoms include:

  • Finding bowel movements difficult and painful 
  • Having a bowel movement fewer than three times a week
  • Having to strain a lot to pass a stool
  • Bloating
  • Your stools look like small, hard pellets

If you have more severe constipation, your symptoms may include:

  • Having a swollen and hard stomach which may be painful
  • Losing your appetite
  • Feeling sick
  • Being sick
  • Having liquid diarrhoea when you do have a bowel movement
  • Headaches
  • Feeling confused and restless
  • Finding it hard to pass urine 

What causes constipation?

You may experience constipation after cancer treatment. This is common and is often a side effect of chemotherapy, surgery or medications required as part of your treatment. The cancer itself may also cause you to have constipation, for example, if you have a tumour in the abdomen or bowel. Certain medications (such as some pain relief medications), not enough fluid or fibre intake, stress and lack of exercise can also contribute to constipation. There may be a variety of reasons why you have constipation making it difficult to know how to manage it. Below are some helpful tips and advice to try.

Foods to help constipation

Changing your diet can help manage your constipation. This could be a temporary change and you can return to your normal diet once your constipation has eased or when you finish your cancer treatment. 

You could try including more high fibre foods in your diet, as this can help to keep bowel movements regular. There is a list below with ideas of high fibre foods to add or swap into your diet. It’s important that you drink plenty of fluids when you have constipation. This is because fluids can help soften your stools and make them easier to pass. High fibre diets can cause dehydration because the fibre draws water from your body, so you need to drink lots of fluids such as water throughout the day. Aim to drink eight to 10 cups of fluids each day.

Avoid drinks that will make you more dehydrated such as alcohol, caffeinated and fizzy drinks. There are plenty of hydrating alternatives you can try such as herbal teas, isotonic drinks and water.

High fibre foods for constipation relief:


Other constipation remedies

Taking daily light exercise can also help to get your bowels moving. We understand it may be difficult to find the energy to exercise during your cancer treatment, so don’t overdo it and instead take it easy and keep within your limits.

What causes bloating and gas?

It’s normal to produce wind or gas (flatulence) as part of digestion, but sometimes you may experience stomach bloating during or after cancer treatment which can cause you to feel like you have more gas than usual. Too much gas can sometimes affect the shape of your large bowel.  If you’re having radiotherapy to the pelvic area, large amounts of gas in the bowel can affect the area being treated. To help reduce gas in your bowel you can make changes to your diet and lifestyle. Remember that these are temporary changes and once you have finished treatment you can return to your normal diet.

Try to avoid the following if you’re experiencing bloating and gas:

  • Drinking alcohol and gassy drinks, such as beer and fizzy drinks
  • Smoking 
  • Caffeinated drinks like coffee and energy drinks
  • Chewing gum
  • Talking whilst you’re eating as this makes you swallow more air
  • Drinking lots of fluid when eating a meal
  • Foods that make you more bloated than usual, such as dairy if you’re lactose intolerant
  • Foods that cause gas and bloating such as lots of high fibre foods and foods which contain artificial sweeteners, for example, highly processed food

Here are some helpful tips that may help reduce gas in the bowel:

  • Sip your drinks and chew your food slowly to reduce the amount of air you swallow
  • Try to be as active as you can each day to encourage bowel movement
  • Ensure you drink enough fluid and aim for at least eight to 10 cups a day
  • Allow hot drinks to cool down before you drink them
  • Try not to skip meals and instead try to space your meals out evenly

You can add things to your diet that help to get rid of bloating and gas. Here are some examples:

  • Some herbs and spices, such as ginger and peppermint
  • Oats, for example in porridge
  • Probiotics, prebiotics, live yoghurts and fermented milk products, such as kefir. If you’re having chemotherapy, you should avoid probiotic drinks because there is a risk of infection

Side effects such as constipation, bloating and gas can be difficult to cope with. At GenesisCare, we’re here to help and support you throughout your cancer journey, so please get in touch if you have any questions or concerns about the side effects you’re experiencing, your nutrition and cancer treatment.

Managing diarrhoea

Diarrhoea and symptoms

Some cancer treatments such as chemotherapy and radiotherapy can cause diarrhoea. Side effects can be mild but some people can experience more severe diarrhoea. If you’re experiencing these symptoms, please get in touch with your doctor as soon as possible.

Common signs and symptoms of diarrhoea include:

  • Needing to have a bowel movement more times than usual each day
  • An increase in the amount of stools you produce when you go to the toilet
  • Stools being softer and more watery than usual
  • Cramping pains in your abdomen
  • Feeling sick
  • Urgent need for a bowel movement
  • Feeling bloated in your stomach

You may experience more severe symptoms including:

  • Having a fever or chills
  • Having severe cramping pains in your abdomen
  • Feeling very thirsty
  • Your heart beating very fast
  • Having dark urine
  • Feeling and being sick
  • Having blood or mucus in your poo

These more severe symptoms may be because you are dehydrated or malnourished due to the diarrhoea. This is because your body isn’t absorbing enough water or nutrients. 


What causes diarrhoea?

Diarrhoea can be caused by many things; Treatments such as chemotherapy and radiotherapy to the abdomen or bowel, cancer itself if it is within the bowel, or some medications. Occasionally diarrhoea is caused by food sensitivities.

It can be difficult to know the exact cause of diarrhoea and more than one thing can contribute. Diarrhoea during cancer treatment is common and it’s important to let your clinician know so that we can try and manage your symptoms. Making some temporary changes to your diet may help with this. 

How to stop diarrhoea after cancer treatment

When you have diarrhoea, it’s helpful to eat food that is lower in fibre. Although usually, a high fibre diet is good for you, fibre can make bowel movements more frequent. The table below lists foods that are lower in fibre which may help to stop diarrhoea:

Here are some other helpful tips:

  • Avoid eating more than three pieces of high fibre fruit or vegetables per day. Remember to peel, core and remove any seeds from fresh fruit and vegetables 
  • Reduce your intake of fruit and vegetables with shells or a stringy texture such as peas, sweetcorn, green beans and celery
  • Make sure you cook vegetables well and don’t eat them raw. Raw vegetables can make your symptoms worse
  • Avoid nuts, pulses, lentils and beans because they’re high in fibre
  • Avoid spicy foods as these can upset your digestive tract and make your symptoms worse
  • If you notice a particular food makes your diarrhoea worse, either avoid it or choose a lower fibre alternative until you have finished treatment
  • Limit your dairy intake because dairy products often make diarrhoea worse
  • Try and eat foods that are high in sodium such as soup and broth, because the salt helps your body keep more water
  • Try a hot water bottle if you are getting muscle cramps after cancer treatment
  • Chew your food well and take your time when eating to make the food easier to digest
  • If you don’t have much of an appetite, try to eat little and often throughout the day, this will help avoid fatigue and your body may find the food easier to digest. It can also help if you get sickness during cancer treatment.

When you have diarrhoea, you lose water which can make you dehydrated. It’s important to drink lots of hydrating fluids such as water and avoid drinks that will make you more dehydrated such as caffeinated drinks (coffee and energy drinks). Avoiding diuretics such as alcohol and fizzy drinks which remove water from your body is also advisable if you have diarrhoea.

The best fluids to drink when you have diarrhoea include:

  • Water
  • Herbal teas
  • Isotonic drinks 
  • Soy milk

Aim to drink eight to 12 cups of water each day and try to drink one cup after each bout of diarrhoea. If you’re struggling to do this, you may find it easier to try drinking other hydrating fluids such as the ones listed above. It’s important to stay hydrated because your body needs water to function properly and stay healthy.

Side effects such as diarrhoea can be difficult to cope with. At GenesisCare, we’re here to help and support you throughout your cancer journey, so please get in touch if you have any questions or concerns about the side effects you’re experiencing, your nutrition and cancer treatment. 

Managing fatigue

About fatigue

During your cancer treatment, you may have extreme tiredness and little or no energy. This is cancer related fatigue or cancer tiredness and it’s very common. Cancer fatigue can affect you physically, emotionally and mentally and the degree and duration of fatigue varies from person to person. Although fatigue is not necessarily a nutritional problem, it can affect how much you eat. For example, you may feel too tired to eat or prepare a nutritious meal.

Common fatigue symptoms include:

  • Struggling to get out of bed in the morning
  • Struggling to fall asleep at night and waking up during the night
  • Finding yourself out of breath after completing small tasks, such as getting dressed
  • Lack of energy and motivation to do anything
  • Muscle pains
  • Struggling to think clearly and make decisions
  • Feeling anxious, sad and depressed at times
  • Finding it hard to concentrate on things
  • Loss of interest in your daily activities
  • Losing interest in sex

Improving your nutrition may help you feel less fatigued.

What causes fatigue?

You may be experiencing cancer related fatigue because of your treatment, such as chemotherapy, or because of the cancer itself, and it can be hard to cope with.

Reasons you may be experiencing fatigue:

  • The cancer itself may cause extreme tiredness, for example, if the cancer affects your hormones. Your fatigue may get worse if your cancer becomes more advanced  
  • Your cancer treatment, such as chemotherapy and radiotherapy. Often combination therapies can make your fatigue worse
  • Low red blood cell levels (anaemia)
  • Pain from your cancer or cancer treatment. This can be difficult to deal with and make you feel tired
  • A different health problem such as depression
  • You may not be eating enough because of loss of appetite which means you don’t have enough energy

You may find your tiredness goes away after your cancer treatment or it may last for a while afterwards. It’s important that you speak to your doctor if you have fatigue symptoms.


How to overcome cancer related fatigue

There are various ways to help overcome cancer related fatigue. One of the most important is to make sure you’re eating enough to keep your energy levels up. Although it can be hard to find the energy to eat, and you may not have much of an appetite, it’s important to have a balanced diet. This involves eating foods from all the food groups that your body needs to keep going. 

You may find the following advice helpful.

  • Cook in bulk and freeze your meals so you have food ready easily when you’re feeling tired
  • Cook meals that are easy to prepare and have quick nutritious snacks available
  • Eat more smaller meals throughout the day or try a high energy protein shake
  • Eat food that is high in protein and calories to get lots of nutrition in every bite
  • Add extra calories and protein to your food or drinks
  • Make sure you drink enough water as dehydration may make you feel tired
  • Ask your friends and family to help with your food shopping and preparing meals
  • You may find it useful to keep a diary of what you eat, to make sure you eat enough and have nutritious meals

Fortifying your food

Here are some ideas for fortifying your food if you need to eat more:

Homemade smoothies

If you have fatigue, it’s a good idea to make your own nourishing smoothies using some of the following ingredients:

Further advice

You should also make sure you’re getting enough rest by taking naps during the day if you need to. You can plan this ahead of time but don’t overdo it. It’s important you try not to sit around all day and instead go for a short walk or do some light exercise. This will give you more energy in the long term and will also help improve your mood and appetite. Start off small and then gradually increase the amount of exercise you do. You can speak to your doctor for more advice about exercise or if you’d like an exercise programme tailored to you. You can read more about our exercise medicine service and how it can support you during treatment. 

Finding a balance between rest and light exercise can help with managing fatigue after cancer treatment. When you feel you have a bit more energy, use it to take a short walk or do something you enjoy. If you have a more active day, ensure you find time to rest too. Make any changes gradually and talk to your clinician if you need any advice.

Side effects such as fatigue can be difficult to cope with. At GenesisCare, we’re here to help and support you throughout your cancer journey, so please get in touch if you have any questions or concerns about the side effects you’re experiencing, your nutrition and cancer treatment.

Managing loss of appetite and a change in taste

What causes loss of appetite in cancer patients?

Loss of appetite is one of the most common side effects of cancer treatments. A poor appetite can also be caused by the cancer itself or other side effects of treatment, such as nausea, vomiting and taste changes.

A loss or change of taste during cancer treatment can also happen and can make food less enjoyable. Foods can start to have a bitter, metallic or even salty taste. This is common with some cancer treatments such as chemotherapy or radiotherapy to the mouth.

It’s important that you continue to eat well, even when you don’t feel like eating. Think of food as one of the medications you must take every day. Making sure you eat a nutritious diet can also help with other side effects you may be experiencing such as fatigue and constipation.


Nutrition advice for loss of appetite

  • Eat smaller meals more often throughout the day instead of three large meals
  • Eat two to three nutritious snacks a day in between meals such as cheese with crackers, nuts and dried fruit, biscuits, peanut butter, yoghurt, hard boiled eggs and milk
  • Liquids can add calories and important nutrients when you don’t feel like food. Juices, soups or milkshakes are easy to prepare or you can buy them ready made
  • Get friends or family to help prepare your meals so you don’t get put off eating  
  • Add extra calories to your food or drinks. High calorie nutritional drinks are an easy way of adding extra calories to your diet
  • Try to keep positive about food and eating and focus on what you have eaten rather than what you haven’t
  • If you have days when you have more of an appetite, treat yourself to your favourite foods 
  • Try to make your food look appealing when you put it on the plate. You could add some chopped parsley or have smaller portions

Fortifying your food

Here are some ideas for fortifying your food if you need to eat more:

Homemade smoothies

If you’ve lost your appetite, it’s a good idea to make your own nourishing smoothies using some of the following ingredients:

Nutrition advice to help with a change in taste

  • Season your food well with different herbs and spices, such as oregano or basil
  • Use ingredients with strong flavours such as garlic and lemon juice
  • Marinate your food overnight to increase the flavour 
  • Add sauces, dressings, chutneys and relishes to your food to enhance the flavour
  • Avoid hot and spicy foods as these may make your mouth sore
  • Eat your food when it’s warm and not too hot or cold 
  • Avoid food that tastes strange or bad to you, even if you liked the taste before your treatment
  • Keep your mouth clean and brush your teeth well 

It can also be helpful to use plastic utensils if you have a metallic taste in your mouth

Side effects such as loss of appetite and a change in taste can be difficult to cope with. At GenesisCare, we’re here to help and support you throughout your cancer journey, so please get in touch if you have any questions or concerns about the side effects you’re experiencing, your nutrition and cancer treatment.

Most taste changes experienced during or after cancer treatment should improve over time. Keeping a varied diet and trying different tastes on a regular basis can help to find food that tastes more pleasant. If you find a food unpleasant, put it to one side and come back to it in a week or so, as you may find your taste has improved again in that time.

Managing nausea and vomiting

Nausea and vomiting

Nausea and vomiting during cancer treatment are common and can be difficult to cope with. You may find you lose your appetite and feel tired if you aren’t getting enough nutrients so it’s important that you take any anti-sickness medication as prescribed by your doctor.

You can also help manage nausea and vomiting through your diet. You may need to make some temporary changes to your diet when you’re feeling sick. Try not to worry, sickness often goes away as soon as your cancer treatment ends, so any changes should only be temporary.

What causes nausea in cancer patients?

There are many reasons you may be experiencing vomiting and nausea during your cancer treatment. It may be the cancer itself causing you to feel sick or a side effect of your treatment. 

Here are some common causes of nausea and vomiting:

  • As a side effect of cancer treatment, such as chemotherapy, radiotherapy or hormonal therapies
  • The cancer itself, caused by chemicals made by the cancer or a tumour blocking the digestive tract 
  • Physical changes to the body, such as too much calcium in the blood or liver damage
  • Feelings of anxiety and anticipation. Sometimes this can happen before treatment that you know has caused you to feel sick previously.

If your cancer is more advanced, you may find you are feeling and being sick more often. This could be due to many different reasons such as the cancer itself, dehydration, constipation or side effects of different drugs. If you are feeling and being sick frequently or you feel it is not under control, please get in touch with your consultant or treatment team who can help you manage your sickness.


How to eat better when you feel nauseous

It’s important that you maintain a balanced diet when going through cancer treatment and try to eat as much as you can. This can be difficult when you’re feeling nauseous so here are some useful tips on how to stop nausea during cancer treatment:

  • Try to eat at times when you don’t feel as sick and don’t force yourself to eat 
  • Eat dry food when you wake up in the morning to settle your stomach. Plain toast or crackers are good options
  • Eating little and often throughout the day as this is easier to digest
  • Eat your meals next to an open window to get some fresh air
  • Get your friends and family to prepare and cook meals for you when you’re feeling nauseous so the smell doesn’t make you feel worse
  • Eat slowly and chew your food well to make it easier to digest
  • Wait until your food has cooled down before eating it 
  • Rest for a while after you’ve eaten, but try not to lie down for at least an hour afterwards
  • Eat a small meal a few hours before your treatment, but avoid eating anything just before
  • Avoid eating fried and greasy food which has a strong smell


It’s important to keep hydrated if you have nausea and vomiting and replace any fluids you lose. Try to sip your drinks slowly between your meals or use a straw.

The following drinks may help to ease any nausea and vomiting:

  • Clear, sweet liquids such as fizzy drinks or isotonic drinks 
  • Peppermint tea
  • Ginger beer
  • Mineral water
  • Fruit juice, except orange and grapefruit juice which can upset your stomach

Side effects such as nausea and vomiting can be unpleasant and difficult to cope with. At GenesisCare, we’re here to help and support you throughout your cancer journey, so please get in touch if you have any questions or concerns about the side effects you’re experiencing, your nutrition and cancer treatment.