Nutrition Tips to Manage the Side Effects of Cancer Treatment

This article is republished from Saint John’s Cancer Institute, a cancer research institute dedicated to the understanding and curing of cancer in order to eliminate patient suffering worldwide.

Radiation, chemotherapy, and other medications used to treat cancer can cause a wide range of side effects. These include taste and smell changes, sore throat, swallowing difficulties, nausea, fatigue, poor appetite, and more. These tips, from the experts at Saint John’s Cancer Institute, can help you manage them.

Taste and Smell Changes

Causes: Cancer and Cancer treatment can cause changes in your senses of taste and smell.

Symptoms: How foods taste and smell can change from day to day, and these changes may affect your appetite.

Tips to Prevent

To find foods that are appealing, try experimenting with new foods or cuisines, marinades, spices, and ways of preparing what you eat. Practicing good oral care is generally helpful.

Oral Care Tips:

  • To keep your mouth clean and healthy, rinse and brush your teeth after meals and before bed.
  • Before eating, rinse your mouth with a solution of 1 quart water, ¾ teaspoon salt, and 1 teaspoon baking soda.
  • Avoid mouthwashes that contain alcohol.

Loss of Taste Tips:

  • Choose foods with tart flavors.
  • Blend fresh fruits into shakes, ice cream, or yogurt.
  • Eat frozen fruits.
  • Select fresh vegetables.

Salty, Bitter, Acidic, or Metallic Taste Tips:

  • Add sweeteners or a little bit of sugar to foods.
  • Season foods with herbs, spices, and other seasonings.
  • Use plastic utensils or chopsticks.
  • Add lemon juice or other flavorings to water.
  • Suck on sugar-free lemon drops, gum, or mints.

Meats Taste Strange Tips:

  • Choose other protein rich foods like beans, lentils, or tofu instead of meat.
  • Marinate and cook meat in sweet juices, fruits, acidic dressings, or wine to improve the taste of meats.

Foods or Drinks Smell Unpleasant Tips:

  • Choose foods that do not need to be cooked.
  • Serve foods cold or at room temperature.
  • Avoid the kitchen during meal cooking time to avoid food smells.
  • Eat in cool, well-ventilated rooms.
  • For protein drinks and other beverages, use a cover on the cup and drink with a straw.

Sore or Irritated Throat

Causes: Certain types of cancer, some chemotherapy agents, or radiation therapy to the head, neck, or chest area can make your throat sore. Heartburn and gastric reflux can also cause a sore throat.

Symptoms: n/a

Tips to Prevent

Food Choices to Manage a Sore Throat:

  • Eat foods that are bland, semi-solid or soft, and easy to swallow.
  • Make smoothies with soothing fruits.
  • Choose soothing room-temperature or cool foods.
  • Do not drink alcoholic beverages.
  • Ask your health care provider whether a nutritional supplement would be helpful.
  • Avoid foods that are likely to irritate your throat, including: tart or acidic beverages and foods, salty foods, coarse or rough-textured foods, or strong or spicy flavorings.

Tips to Help Heal Your Throat:

  • Take small bites, chew your food well, and swallow carefully. Allow ample time between bites.
  • If gastric reflux or heartburn is a problem, stop eating 2 to 3 hours before bed and sleep with your head propped up.
  • Do not use tobacco products or commercial mouthwashes that contain alcohol.
  • Talk to your doctor about medications that can numb and soothe your mouth or throat.

Swallowing Difficulties

Causes: People with Cancer may have dysphagia (difficulty swallowing foods or liquids) due to mouth or throat sores caused by cancer treatments or by cancer of the head or neck.

Symptoms: They may find it painful to chew foods that are hard or rough, and they may be unable to swallow thin liquids (like water) without coughing or choking.

Tips to Prevent

Changes to the texture and consistency of the foods you eat and the liquids you drink may be helpful. Your doctor may refer you to a registered dietitian (RD) or speech-language pathologist (SLP). These specialists can recommend the best diet and fluid consistency for you. The SLP can also teach you exercises and positions to improve your swallowing ability.

Managing Swallowing Difficulties Tips:

  • Talk with your healthcare team!
  • Follow the advice of your SLP and RD.
  • Eat three to five small meals each day.
  • Consume liquid nutritional drinks if you can’t eat enough solid foods at meals.
  • Drink 6 to 8 cups of fluid each day. If necessary, thicken beverages and other liquids so they are easier to swallow.

Sore Mouth

Causes: Cancer and cancer treatments can sometimes make your mouth feel sore and make chewing and swallowing difficult.

Symptoms: n/a

Tips to Prevent

  • Choose soft, bland foods served cold or at room temperature.
  • Try pureed foods. This makes the food easier to swallow.
  • Moisten foods with broth, soup, sauces, gravy, butter, or margarine. You can also dip or soak foods in whatever you are drinking.
  • Eat high-protein, high-calorie foods to speed healing.
  • Ask your doctor or registered dietitian (RD) about nutritional supplements, such as liquid meal replacements.
  • AVOID foods that are likely to irritate your mouth, including: acidic foods, irritating spices, seasoning, and condiments, rough, dry, or course foods, or alcoholic and acidic beverages.

Dry Mouth or Thick Saliva

Causes: A common side effect of radiation therapy, some types of chemotherapy, and some medicines.

Symptoms: May have problems eating, talking, and sleeping. Dry mouth also raises your risk for dental cavities and mouth infections.

Tips to Prevent

  • Drink 8 to 10 cups of fluid a day to keep your mouth moist and help loosen thick saliva.
  • Limit drinks with caffeine and alcoholic beverages.
  • Carry a water bottle with you.
  • Eat soft, bland foods that are room temperature or cold.
  • Moisten foods with broth, soup, sauces, gravy, butter, or margarine.
  • Talk with your registered dietitian (RD) about whether you should use liquid meal replacements.
  • To increase saliva, try tart foods and drinks. Avoid acidic foods and drinks if you have a sore or tender mouth.
  • Enjoy soothing frozen fruits.
  • Suck on frozen fruit pops.
  • Chew sugar-free gum or suck on sugar-free candy to stimulate saliva.
  • Keep up with good oral care and hygiene.

Good Oral Care and Hygiene:

  • Brush your teeth with toothpaste and a soft-bristle toothbrush after each meal and snack.
  • Rinse your mouth before and after meals with plain water or a mild, homemade mouth rinse (1 quart water mixed with ¾ teaspoon salt, and 1 teaspoon baking soda).
  • Alcohol can make dryness worse, so choose alcohol-free mouthwashes, such as Biotene.
  • Swish and spit with club soda or lemon-lime soda to help loosen and remove dry or thick saliva.
  • Floss your teeth every day.
  • Talk to your doctor about using oral moisturizers, saliva substitutes, and saliva-stimulating medications.
  • Chew antibacterial chewing gum to help reduce gum inflammation and stimulate the production of saliva.
  • Avoid smoking and chewing tobacco.

Poor Appetite


  • Sadness, depression, grief, anxiety.
  • Illnesses or medical conditions, such as fever or pneumonia.
  • Cancer and cancer treatments, such as chemotherapy and radiation.
  • Certain medications.

Symptoms: *Some symptoms and side effects related to a poor appetite are particularly serious. Call your doctor if:

  • You lose 5 pounds or more.
  • You can’t eat for more than a day.
  • You have pain with eating.
  • You have infrequent, strong-smelling, or dark-colored urine.
  • You vomit for more than 24-hours.
  • You have pain that is not controlled.

Tips to Prevent

  • Discuss the medications you take with your doctor. Some medications for constipation, nausea, or pain can cause poor appetite.
  • Ask your doctor if a medication to increase your appetite could be right for you.
  • Eat small amounts throughout the day.
  • Choose drinks that are nourishing, high in calories, and high in protein.
  • Make every bite count by choosing higher calorie foods.
  • Move around when possible.
  • Make your surroundings cheerful.
  • Keep a list of favorite recipes and meals on hand for friends and family members who help with cooking or shopping

Keep your pantry and freezer well stocked with foods that make quick and easy meals and snacks.

  • Use the clock, TV shows, or commercial breaks to remind you to take a sip, eat a bite, or have a snack.

Tips to Heal Your Mouth:

  • Tilt your head back and forth to help foods and liquids move to the back of the throat for swallowing.
  • Drink through a straw.
  • Remove food and germs by rinsing your mouth often.
  • Avoid tobacco and mouthwashes that contain alcohol.
  • Ask your doctor about medications to soothe your mouth or throat.

Nausea and Vomiting

Causes: By cancer, or it may be a side effect of chemotherapy or radiation therapy. Other causes of nausea and vomiting include pain, fatigue, illness, medications, and the stress of coping with cancer.

Symptoms: Feeling nauseous for a long time can affect your appetite and could cause you to lose weight. If you vomit a lot, you can become dehydrated (lose too much fluid).

Tips to Prevent

*The best treatment for nausea or vomiting will depend on what is causing the problem.

  • For nausea due to chemotherapy or radiation therapy, you may need to take prescription anti-nausea medication or a particular schedule to control symptoms and better tolerate meals and specific foods.
  • If nausea is caused by anxiety or fatigue, your health care team may recommend physical and mental relaxation techniques.
  • If nausea is a side effect of medications of supplements, you may feel better when you take the medication with food instead of on an empty stomach.
  • Eat six to eight small meals a day instead of three large.
  • Sip on beverages that provide calories.
  • Drink clear liquids as often as possible after vomiting to prevent dehydration and keep your mouth clean.
  • Freshen your mouth by rinsing it with a solution made of 1 teaspoon of baking soda, ¾ teaspoon of salt, and 1 quart of warm or cool water.
  • Eat bland foods.
  • Eat dry foods.
  • Avoid strong odors.
  • Create a peaceful, relaxed eating space to help calm you and make eating easier.
  • Suck on tart hard candies, such as lemon drops, to relieve nausea and get rid of any bad taste in your mouth.
  • Avoid eating your favorite foods when you feel nauseous so you don’t develop a dislike of those foods.
  • Try taking 0.5 to 1 gram of ginger extract along with prescribed anti-nausea medications.
  • Try using Sea-bands.


Causes: May be a side effect of cancer treatments such as radiation therapy to the bowels or chemotherapy. When a therapy causes changes in the gut function, more gas than usual may be the result. Other possible causes include:

  • Diarrhea, constipation, or other changes in bowel function.
  • Drinking milk and dairy foods if you have trouble digesting lactose (the natural sugar in milk).
  • Swallowing too much air as you eat or drink.
  • Eating high-fiber foods.

Symptoms: n/a

Tips to Prevent

Avoid swallowing too much air by:

  • Eating slowly.
  • Chewing gum.
  • Not talking while eating or chewing.
  • Not drinking with straws.
  • Not chewing gum.

Manage lactose intolerance (if you have it) by:

  • Using over-the-counter digestive enzymes for lactose.
  • Choose lower lactose dairy foods like yogurt, sweet acidophilus milk, or reduced-lactose milk.

Limit excessive gas caused by eating high fiber foods by:

  • Avoiding the foods that cause gas (such as beans or certain vegetables) or limiting the amount that you eat at one time.
  • Using an over-the-counter medication like Beano to lessen the gas.


Causes: Fatigue is the most common side effect of cancer and cancer treatment. You may feel fatigued due to the cancer itself or because of stress, diarrhea, dehydration, chemotherapy, daily radiation treatments, anemia, or infection.

Symptoms: Weakness, tiredness, sadness, difficulty thinking, lack of energy, and dizziness.

Tips to Prevent

  • Keep a diary of your symptoms. Write down things that make you more fatigued and things that make you feel better. Note how often you become fatigued and how long the fatigue lasts.
  • Nap during the day and try to get good-quality sleep at night.
  • Try to do mild exercise or physical activity each day.
  • Ask your friends and family to help you shop for food and prepare meals.
  • Stock your kitchen with easy-to-prepare and easy-to-eat foods.
  • Try to eat small, frequent meals and snacks that consist of favorite foods and beverages.
  • Choose foods and drinks that are good sources of calories, protein, and fiber.
  • Drink at least 8 cups of fluid per day.
  • Limit caffeine-containing beverages to two per day and consume them early in the day so they don’t interfere with your sleep.
  • Enjoy your meals in a pleasant environment.


Causes: Certain types of cancers, treatment such as chemotherapy, radiation therapy, surgery, and bone marrow or stem cell transplant, infection, certain medications, or emotional upset.

Symptoms: Uncontrolled diarrhea can lead to weakness, poor appetite, dehydration, and weight loss.

Tips to Prevent

  • Drink plenty of mild, clear liquids during the day.
  • Drink at least 1 cup (8 ounces) of liquid after each loose bowel movement.
  • East several small meals and snacks throughout the day.
  • Drink and eat small portions of foods that provide sodium and potassium (two minerals that your body loses when you have diarrhea).
  • Eat foods high in pectin, to firm up your bowel movements.
  • Avoid greasy, fried, spicy, and very sweet foods.
  • Avoid caffeine and alcohol.
  • When you have diarrhea for more than a day or so, limit milk and dairy foods to no more than 2 cups a day. Prolonged diarrhea can cause temporary lactose intolerance.
  • Limit drinks and foods that cause gas, including carbonated drinks, vegetables in the cabbage family, and dried beans and peas.
  • If you want a carbonated drink, stir it or pour it into a glass to lessen the bubbles.
  • Avoid foods, chewing gum, and cadies made with sorbitol, xylitol, or mannitol.
  • When you have diarrhea, limit high fiber foods.

Ask your doctor, nurse, or registered dietitian whether it is appropriate for you to:

  • Take a vitamin and mineral supplement.
  • Eat foods that contain probiotics or take a probiotic supplement.
  • Use a bulking agent containing psyllium fiber.



  • When you do not take in enough fluids to replace fluids lost through bodily functions like urination, bowel movements, and sweating.
  • A sore mouth or throat, nausea, or poor appetite may keep you from drinking enough fluids.
  • Vomiting, diarrhea, fever, and/or excessive sweating can cause above-normal fluid losses.
  • If you urinate more than usual because of uncontrolled diabetes or use of water pills.
  • Some medications, caffeine, and alcohol.


  • Thirst
  • Dry mouth and tongue
  • Dry and cracked lips and skin
  • Dark-colored urine
  • Headache
  • Voiding frequent, small amounts of urine
  • Constipation (hard, small stools)
  • A heart rate that is faster than your usual heart rate
  • Confusion or changing in thinking
  • Dizziness or light-headedness when standing up

Tips to Prevent

  • Drink small amounts of fluids as often as you can tolerate them. Drink at least a cup of fluids every 1 to 2 hours. Each day you should drink about 8 to 12 cups of liquids a day. (Drink more if you have diarrhea or are vomiting.)
  • Ask family and friends to encourage or remind you to drink more fluids.
  • Keep a water bottle with you during the day to sip on.
  • Keep a glass of water beside your bed to sip on at night.
  • Drink liquids with meals.
  • In addition to plain water, also drink fruit juices, soft drinks, flavored waters, decaffeinated coffee and tea, sports drinks, milk, and other beverages.
  • Eat foods that are high in fluids.
  • Avoid alcoholic beverages.
  • Limit drinks with caffeine to two a day.



  • Being less active than is normal for you.
  • Eating or drinking less than your usual amounts.
  • Taking certain medications, such as medications for nausea or pain.
  • Taking calcium or iron supplements.


  • You cannot move your bowels.
  • You have bowel movements less often than normal.
  • You have to push harder than usual to move your bowels.
  • Can be painful or uncomfortable.

Tips to Prevent

  • Eat at about the same times each day.
  • At breakfast, drink a hot beverage or eat hot cereal to stimulate bowel movement.
  • Try to drink at least 64 fluid ounces (8 cups) of liquids each day.
  • Discuss with your registered dietitian (RD) whether you should increase the amount of fiber you consume each day. If you plan on adding fiber, do it slowly.
  • Increase the amount of fiber you eat by no more than 5 grams each day.
  • If possible, increase the amount of physical activity you do.
  • Ask your doctor before using bulking agents or over-the-counter stool softeners or laxatives.
  • Allow yourself enough time in the bathroom to have a bowel movement. Try not to rush yourself.

This article is republished from Saint John’s Cancer Institute, a cancer research institute dedicated to the understanding and curing of cancer in order to eliminate patient suffering worldwide.

Last updated or reviewed on March 2, 2023

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