Common cancer treatment side effects

Fatigue

Most people with cancer experience some level of fatigue during treatment.⁶ Many people begin to feel better within 6-12 months of finishing treatment, though for some it can persist for months or years. ⁶

With cancer-related fatigue, people generally feel constantly tired, exhausted and weak.⁶ It’s more severe than “regular” fatigue and generally doesn’t improve with extra rest or sleep.⁶ Instead, it can affect your daily life and leave you feeling drained and unmotivated. While the severity and impact of cancer-related fatigue differs between people, you may experience muscle aches and pains, low energy levels, or difficulty sleeping and concentrating.⁶

Why it happens:

Fatigue can be the result of cancer treatment lowering the number of red blood cells in your body (which is called anaemia), as well as other factors including:

• Pain relief medications

• Side effects of treatment including nausea, digestive problems or pain

• The demanding impact of intense treatment like chemotherapy or radiation therapy on your body

• Changes to your blood levels and hormones^6,7

• Inadequate nutrition and poor dietary choices

• Stress, depression, anxiety or mood fluctuations

• Low quality or insufficient sleep

• Reduced physical activity

• Your body needing extra energy or calories to support healing and recovery (yet you’re not meeting your additional requirements).⁴

Some people find fatigue one of the most difficult side effects of treatment, due to its impact on your wellbeing and ability to continue normal daily activities. However, there are strategies which can help you manage fatigue.

Management strategies:

• Prioritise high-protein and iron-rich foods.⁶

• Introduce gentle, regular daily exercise such as walking, yoga or stretching if you’re able.⁷ Start small and gradually increase the amount of movement you’re doing if you feel well enough. Regular exercise can improve appetite and energy levels and support your sleep.⁶

• Maintain a sleep schedule. Rest when you’re feeling exhausted but try to minimise napping outside of your regular sleep times.⁷ Go to bed and wake up at around the same time each day if possible, aiming for 7-9 hours of sleep.^6,7

• Implement a bedtime routine involving the same evening rituals daily to help signal to your brain that it’s time to prepare for rest.⁶ This can help you fall asleep faster and sleep more deeply.

• Eat a nutritious diet. Include a wide variety of whole foods such as proteins, healthy fats, fruit and vegetables, dairy products and whole grains, and ensure you’re getting enough energy and nutrients each day to support your energy levels.⁵ If you’re unsure, speak to your healthcare professional or an oncology dietitian.

• Make things easy for yourself – order groceries online instead of going in-store, meal prep in advance so you don’t have to cook when you’re overly tired, and accept offers from friends and family to help with the shopping or cooking. Consider using meal delivery services or stocking frozen meals in your freezer for when you don’t have the energy to cook.

• Stock your kitchen with ready-made snacks like muesli bars, dried fruit and nuts, and wholegrain crackers, and keep some on-hand in your bag or car for when you need some extra energy.⁷

• Stay hydrated.⁵

• Introduce relaxation and meditation techniques into your daily schedule to help manage stress and improve sleep.⁷

• Minimise alcohol and avoid smoking. These can interfere with sleep quality and quantity.⁶

Hair loss

While treatments like chemotherapy and radiation therapy are associated with hair loss, other forms like targeted therapy, hormone therapy and immunotherapy more commonly result in hair thinning or slowed growth.⁸

Why it happens:

Hair loss can be a side effect of some treatments, caused by unintentional damage to healthy cells including hair roots or follicles.⁸ Hair loss can be upsetting but is usually only temporary.

If you’re experiencing hair loss or thinning on your head, eyebrows, eyelashes or other areas of your body, rest assured that most people regrow a reasonable amount of hair within 4-12 months post-treatment.⁸

Management strategies:

• Some people decide to cut off their hair before beginning treatment to minimise the emotional impact of watching it fall out.⁸ Others wait until they begin to lose their hair before deciding to shave their head.⁸
• You may want to wear a wig, scarf or hat if you prefer to cover your head while you’re losing hair.⁸
• Cold cap therapy (also known as scalp cooling) may help to decrease hair loss by reducing the amount of chemotherapy drugs reaching your scalp.⁹ This aims to protect hair follicle cells from damage, to reduce hair loss.⁹ This therapy is only available in some treatment centres and to certain cancer patients, so check with your healthcare professional to see whether it’s an option for you.⁹
• Use gentle shampoo, conditioner and hair care products and avoid harsh chemicals in products like hair dye and gel.⁹ Air dry your hair or use a cool setting on your hair dryer, and minimise heat styling.⁸
• Gently moisturise your scalp with a fragrance-free lotion regularly and protect your scalp with sunscreen or a hat when outdoors.⁹

Skin and nail changes

You may experience changes to your skin and nails during cancer treatment. These vary depending on the type of treatment you’re receiving, but may include dry or sensitive skin, and peeling or weak nails.¹⁰

Why it happens:

This is the result of cancer treatment damaging the healthy cells involved in your body’s normal processes of skin renewal and nail growth.¹⁰

Management strategies:

• Regularly moisturise your skin using fragrance-free lotions recommended by your healthcare professional to prevent dryness, itching and infection.¹⁰

• Keep your skin folds as clean and dry as possible if you’re struggling with wet sores or peeling in these areas to prevent infection.¹⁰

• Stick to gentle soaps recommended by your healthcare team, avoiding harsh chemicals, alcohols or fragrances in your products.¹⁰ These can be drying or irritating.

• Use SPF30+ sunscreen and protective lip balms whenever you’re exposed to the sun.¹⁰ Wear a hat and long, loose clothing when outdoors.

• If you’re undergoing radiation therapy, avoid applying heating pads, ice packs or bandages directly to treated areas.¹⁰ You can also shave less often or take a break entirely if your skin is painful or sensitive.¹⁰

• Bathe or shower in cool or lukewarm water, and for a shorter amount of time.¹⁰ After drying off slightly, apply a gentle moisturiser to keep as much moisture in your skin as possible.

• Maintain clean, short nails to prevent tearing and breaking, and wear gloves when cleaning or using chemical-containing products.¹⁰

• Avoid manicures and pedicures and opt for loose or open footwear if possible.¹⁰

• Ask your health professional for prescription creams or medications to treat painful or irritating rashes if needed.¹⁰

Pain

Not everyone experiences pain during treatment, but it can be caused by most types of cancer and treatment. If you’re struggling with symptoms like muscle aches, joint pain or burning sensations which are interfering with your ability to eat, sleep, socialise and perform everyday activities, this can usually be improved with pain medication or other strategies.¹¹

Controlling your pain during treatment is important for improving your quality of life throughout this period, and may even help with sleep, mood and energy levels.¹¹ At times, the intensity of your pain may increase and require more significant treatment methods. Consult your healthcare team for support, as they can devise an individual pain management plan based on your unique symptoms and causes.

Why it happens:

The causes of cancer treatment-related pain are numerous but may include:

• A tumour putting pressure on your nerves or other body parts,
• Physical effects of treatments like surgery on your body, causing pain during the treatment process, or afterwards as you recover,
• Experiencing nerve damage or inflammation during treatment
• Some treatment side effects like mouth sores or skin reactions.¹¹

Management strategies:

• Talk to your healthcare team about over-the-counter or prescription pain medications appropriate for your needs and circumstances which may provide some relief.¹²
• Try physical therapy, acupuncture or gentle stretching and movement.¹²
• Apply heat or cold packs to painful areas of your body for temporary relief.¹²
• Treat any symptoms which are causing pain with the help of your healthcare team, like mouth sores or digestive problems.¹²

Low immunity

Many cancer treatments like chemotherapy can temporarily weaken your immune system.

Why it happens:

These treatments can reduce the number of white blood cells in your body, which are needed for your immune system to function normally.⁴ When you have fewer of them, it becomes harder for your body to fight off illness or infection.⁴

Management strategies:

• Take care preparing and storing food to prevent exposure to foodborne illnesses. Learn more about safely storing and cooking food during cancer treatment here.
• Use separate cutting boards and knives to prepare raw produce, and ensure all protein is thoroughly cooked before eating.¹³
• Consume any food leftovers within 24 hours of preparing and refrigerate extra food immediately after cooking.¹³
• Avoid buying pre-made foods at the supermarket, as you don’t know how long they’ve been sitting there for.¹³ Opt for fresh or home-cooked meals as much as possible.
• Ensure you’re consistently meeting your energy, protein and nutritional needs daily to support your body and immune system’s strength and resilience.⁵ If your healthcare professional recommends using an oral nutrition supplement, the Fortisip® product range can help you meet your daily nutritional needs when your usual diet is not enough.¹⁴ Fortisip® formulas provide a good source of protein to support the maintenance of muscle mass,¹⁵ and are high in calories to help improve your bodyweight when you’re unwell or recovering from illness.¹⁴
• Gentle, regular exercise can support immunity.⁴
• Eat a variety of whole foods including lean protein, healthy fats, fibre, fruit and vegetables and dairy products to provide your body with the nutrients it needs for immune protection.^4,5
• Include fermented and fibre-rich foods to support your gut health, as this plays a crucial role in immune health too.⁵

Learn more about making nutritious food choices to support your immune system and health during cancer treatment here.

Nausea and vomiting

Nausea and vomiting are also common side effects of cancer treatment, however anti-nausea medications and other strategies can be effective ways of preventing or reducing these.¹⁶

Why it happens:

• Chemotherapy can unintentionally damage healthy cells in your digestive tract, causing inflammation and sometimes nausea.¹⁶ Chemotherapy drugs may also stimulate the release of certain chemicals in your brain, which can trigger your vomiting response or leave you feeling unwell.¹⁶
• Radiation therapy, particularly when targeting the brain, abdomen or your full body, or when you’re given high doses, can cause nausea and vomiting.¹⁶ This may begin shortly after each session, lasting up to 3-4 weeks. Radiation can damage the healthy cells in your stomach and intestines or stimulate the same area in your brain which makes you want to vomit.¹⁶
• Drugs used in targeted therapy, immunotherapy and stem cell transplants can also cause vomiting or nausea.¹⁶
• In surgery, the anaesthetic or other medications used during the procedure can trigger these side effects too.¹⁶
• Severe pain caused by the cancer itself, the treatment, or other side effects of treatment can also cause nausea in some people.¹⁶

There are also psychological reasons you may feel nauseous before, during or after cancer treatment. Anxiety and stress around treatment can leave you feeling unwell. Some people also experience “anticipatory nausea” where their fear of feeling sick brings on physical symptoms.¹⁶

Management strategies:

• Anti-nausea medicines are regularly given before treatments like chemotherapy and can work well to relieve or prevent these symptoms.⁴ Your healthcare professional or doctor will prescribe the right medication for you based on your circumstances and symptoms.
• Stay hydrated, especially if you’re vomiting, and eat foods that are easy on your stomach.¹⁶ Dry, bland foods like toast, plain pasta, rice or crackers are good options when you’re nauseous.
• Try foods and drinks containing ginger, as these can help settle your stomach.¹⁶ Ginger tea, ginger ale and ginger biscuits are good choices.
• Avoid fried, greasy, sweet and spicy foods while you’re feeling sick.⁴ These can worsen your symptoms.
• Choose foods with minimal odours.¹⁶ Strong smells like fish, onion and garlic can worsen nausea. Eat outside in fresh air and choose cold or room-temperature meal options, as these tend to have more subtle smells.¹⁶
• Eat smaller meals every few hours, instead of three main meals throughout the day.⁴ This helps manage nausea and can be easier on your digestion while you’re nauseous.⁴

Dry mouth, mouth sores and difficulty swallowing

Mouth sores, dryness and swallowing problems can be painful or difficult to manage and may cause problems like unintentional weight loss or low appetite.^4,17 However, these symptoms generally improve and disappear gradually after you finish treatment.⁴

Why it happens:

Treatments like chemotherapy and radiation therapy can damage the cells in your mouth and taste buds, resulting in symptoms like ulcers or mouth sores, a sore throat or dry mouth, and difficulty eating or swallowing.⁴ These treatments may also affect your saliva glands, meaning you may produce less saliva and struggle with a dry mouth.^4,17

Radiation therapy or surgery affecting your jaw, mouth or throat can make chewing and swallowing difficult too – usually only temporarily.¹⁷

Management strategies:

• Practice good oral hygiene to protect your teeth, relieve discomfort and help your mouth heal.⁴ You can do this by quitting smoking, brushing your teeth regularly gently using a soft toothbrush, and following up with an alcohol-free mouthwash.
• Stay hydrated to keep your mouth moist.¹⁷ Reduce your intake of caffeine including in coffee, tea and energy drinks, and regularly apply lip balm.¹⁷
• Maintain a nutritious, adequate diet including plenty of fruit and vegetables, protein, whole grains and dairy products.¹⁷ This can help your mouth (and body) heal more efficiently.
• Avoid foods which irritate your mouth or cause pain including hard, spicy, salty or acidic foods.⁴ Opt for soft, moist foods, or nutrient-rich drinks like smoothies, soups or broths if you’re struggling to chew and swallow food.⁴
• If swallowing is painful, try changing the consistency of your food by pureeing or finely chopping it.¹⁷ Eat softer foods while your symptoms persist.
• If needed, speak to your doctor about medications to help reduce your pain or discomfort while eating or drinking.⁴

Anaemia

Anaemia is a condition in which you don’t have enough red blood cells in your body.¹⁸ These cells are responsible for transporting oxygen from your lungs to the rest of your body, so having low levels of these cells can cause health problems like extreme fatigue, dizziness, shortness of breath and heart complications.¹⁸

Why it happens:

Treatments like chemotherapy and radiation can damage the healthy cells in your bone marrow which are responsible for producing red blood cells.¹⁸

Management strategies:

• Conserve your energy – don’t try to do too much. Let the people around you help with daily tasks like household chores and cooking.¹⁸
• Rest when needed but try to limit naps to help you maintain a regular nighttime routine and sleep schedule, as mentioned.¹⁸
• Take a short walk or do some gentle exercise daily if you’re able.
• Maintain a nutritious, balanced diet.^4,18 Foods rich in protein and iron are particularly beneficial.^4,5 Make sure you’re eating enough calories, protein and nutrients every day to support your energy levels and recovery.^4,5 If you’re finding this difficult, speak to your healthcare professional about using an oral nutrition supplement (ONS) like Fortisip®, which can help you meet your daily nutritional needs when your usual diet is not enough.¹⁴

Changes in taste and smell

Taste and smell changes affect up to 80% of cancer patients. This can make it more difficult for you to enjoy food and maintain a varied, healthy and balanced diet.¹⁹

Why it happens:

Some treatments can damage the healthy cells in your taste buds and receptors, making some (or all) food and drink suddenly taste metallic or unpleasant and resulting in loss of appetite for many patients.^4,19

Learn more about the different causes of appetite loss in cancer and treatment and how to manage it here.

Cancer treatment can also damage the nerves which send sensory signals to your brain.¹⁹ Or they can affect your nerve endings, making you more sensitive to cold and heat.¹⁹

Some people find their sense of smell and taste returns to normal within a couple of months after treatments like chemotherapy, or slightly longer after radiation, though in rare cases these changes can be permanent.^4,19 There are many strategies you can use to help alleviate the effects of this symptom on your lifestyle and ability to maintain a healthy diet.

Management strategies:

• Your tastes may change throughout the course of your treatment. If you usually have a “sweet tooth”, you might find you begin to prefer savoury options – and vice versa.²⁰ Keep experimenting with new foods and flavours to find what works for you, and don’t force yourself to eat foods you’re not enjoying.^19,20
• If you have a metallic taste in your mouth, try using plastic or bamboo utensils.²⁰
• Add herbs and spices to flavour your foods.^19,20
• Add fresh lemon or lime juice, mint, cucumber or sugar-free cordial to water to make it easier to drink if you’re finding it hard to stomach.²⁰
• If you’re sensitive to smells, focus on cold or room-temperature foods with minimal odour. Ask a loved one to prepare food for you if you can’t stand the smell of cooking, or try nutritious ready-made meal delivery services as guided by your doctor or dietitan.^19,20
• If you become more sensitive to temperature, avoid very cold and hot foods like ice cream or soup.²⁰ Stick to lukewarm or room-temperature meals. Some people find their sensitivity to temperatures and textures decreases, so be careful when eating or drinking very hot or cold food and drink.
• Look for alternative options. If you find a certain protein like meat becomes repulsive, try other sources of protein like seafood or tofu to ensure you’re still getting the nutrients you require, with less discomfort.^19,20 Focus on balanced, nutrient-dense meals, aiming to meet your protein, calorie and nutritional needs daily. If this is challenging, ask your healthcare professional or dietitian whether an ONS like Fortisip®’s Compact Protein range can help you meet your daily nutritional needs when your usual diet is not enough,¹⁴ especially if you don’t feel like eating or you’re struggling with discomfort.

Blood clots (DVT)

Blood clots or deep vein thrombosis (DVT) is the formation of a blood clot in a deep vein, most often the lower leg, thigh or pelvis, but sometimes in the arm.²² This clot can break away and travel elsewhere in the body in some cases, becoming extremely dangerous if it reaches an area like your lungs.²² Symptoms of DVT include swelling, pain, tenderness or skin redness.²²

Why it happens:

During some treatments like chemotherapy, your risk of developing blood clots is much greater than normal.²² Once you’ve had cancer, your DVT risk continues to be elevated.

During cancer treatment, the following factors can increase your chances of developing a blood clot:

• Injury to a vein during surgery
• Slowed blood flow from lying down for a long time
• Having a catheter in specific veins – this is a common cause of DVT in people receiving long-term chemotherapy.²²

Management strategies:

• Speak to your doctor about preventative medications to reduce your DVT risk. If you’re having surgery or getting a catheter inserted into a central vein, you may benefit from blood thinning medication.²²
• Wear compression socks or stockings to boost blood flow.²²
• Try gentle movement or exercise daily – even light stretching or yoga is useful.²²

Insomnia or sleep difficulties can be caused by the strong medications involved in cancer treatment, other side effects of treatment, long periods in hospital, or stress and anxiety.²⁵ Up to half of people being treated for cancer struggle to fall or stay asleep.²⁵ Sleep is vital for your health, strength, energy and recovery, so speak to your healthcare team about introducing strategies to improve your sleep.

Many people with cancer lose weight during their illness or treatment.²⁶ Your energy needs often increase during this time, and many people struggle to meet these requirements.^5,26 Side effects of treatment can also make it more difficult or painful to eat or reduce your appetite.²⁶ Maintaining your bodyweight and muscle mass is crucial to help you stay strong and support your recovery, so talk to your healthcare team about strategies to assist you.²⁶ Your doctor or dietitian may suggest introducing an ONS like Fortisip® Compact Protein which can help you meet your daily nutritional needs when your usual diet is not enough.¹⁴

Some people gain weight as a result of treatment too.²⁶ For example, certain chemotherapy drugs can cause fluid retention, or hormone therapy may alter your normal hormone levels and slow your metabolism.²⁶ Fatigue, stress and anxiety can cause changes to your diet and exercise habits too.²⁶ Speak to your doctor if you’re worried about weight gain, and never try to lose weight during cancer or treatment without guidance.