What side effects can be expected from undergoing cancer treatment?

There are side effects associated with radiation therapy and high-dose chemotherapy. This article describes some of the most common side effects and ways to relieve them.

Every person’s reaction to treatment is unique, and some of these side effects might not affect you or you might have a side effect not listed here. No one can predict which side effects will affect you or how severe they might be. Only you know how you feel. Please make sure to tell your nurse, physician assistant or doctor how you are feeling so he or she can intervene early to try to make you feel better.

Chemotherapy and radiation destroy cancer cells. They also destroy normal cells in the process. These include cells of the protective lining of the mouth and the gastrointestinal tract. This can cause sores in the mouth and/or throat that are painful. The pain can be mild to severe. The gastrointestinal tract can become irritated, which causes nausea, vomiting, and diarrhea. These conditions are not permanent, and you might receive medicines to help relieve your symptoms. As you recover, your mouth and throat will begin to heal, and the nausea and vomiting will also improve.

Certain side effects can happen months or years after your treatment. They can be caused by radiation or chemotherapy, and some can be permanent, such as sterility. Secondary malignancies have been reported in some patients receiving radiation and certain types of chemotherapy. Ask your doctor for your specific risk. The risk varies depending on your age, menopausal status for women, previous history of radiation, type and doses of chemotherapy and disease.


Diarrhea is common during your treatment and can continue after your cancer treatment. Your treatments might cause you to have:

  • Abdominal bloating or cramps
  • Thin or loose stools
  • Watery diarrhea
  • Sense of urgency to have a bowel movement

Chemotherapy can cause patients to be temporarily ‘lactose intolerant’. If you notice more diarrhea or loose stools with milk or milk products, you may want to decrease or cut out these foods or drinks until your diarrhea is controlled.


Tell your nurse or doctor if you have diarrhea more than two or three times per day or if you notice mucus or blood when you have a bowel movement. Your healthcare provider might prescribe medicine for you.

  • Drink at least six 8-ounce glasses of fluids per day. Choose beverages without caffeine such as pulpless fruit juices, broths, or flat sodas.
  • Instead of drinking liquids with your meals, drink liquids between meals.
  • Tell your healthcare provider if you think you need an anti-diarrheal medicine. You might be instructed to take an over-the-counter anti-diarrheal medicine after each bowel movement to control mild diarrhea. (Please note: Follow the directions on the medicine container.)
  • Eat cooked, peeled, or canned fruits and vegetables. Avoid fruits or vegetables with skins or seeds such as berries and grapes. Avoid cabbage, broccoli, corn and peas, as these vegetables can cause you to have gas.
  • Eat small, frequent meals instead of three large meals. Chew foods thoroughly. Eat warm food rather than very hot or very cold food.
  • Avoid eating spicy foods or foods that are high in fat. Milk and foods high in sugar also cause diarrhea for some people.
  • If your rectal area becomes sore because of frequent bowel movements, or if you experience itching, burning, or pain during bowel movements, try warm sitz baths (sit in a few inches of warm water in a bathtub). You might be instructed to add Epsom® salts or another type of tablet to the water. Afterward, pat the area dry (do not rub) with a clean, soft towel. Check with your healthcare provider to determine if medicated creams or pads are appropriate treatments for you.
  • If you have severe or persistent diarrhea, you might become dehydrated. (See “Dehydration” section of this article.)

Changes in your sense of taste

Many patients complain that foods just do not taste the same as they did before treatment. A metallic taste in your mouth is common. This will resolve over time.


  • Tart fruits or fruit-flavored sourballs might decrease the metallic taste in your mouth.
  • Foods that are chilled might be better tolerated, such as milkshakes, flavored gelatin, pudding, and applesauce.
  • Clean your mouth thoroughly before you eat to help improve the taste of food.
  • Try using strong flavorings or seasonings, such as salad dressings, to help provide food with more pleasant flavor.
  • If your taste is really dulled, you can try increasing the aroma of the foods you eat. Usually if the food smells good, it will also taste good.
  • Liquid nutritional drinks might be helpful.

Nausea and vomiting

Both chemotherapy and radiation therapy cause nausea and vomiting. You will be given medicine to prevent or decrease these side effects.

Nausea may or may not be accompanied by vomiting. Nausea might last from a few hours to several weeks after treatment.

If a certain medicine is not helping your nausea, tell your nurse, and a different anti-nausea medicine can be prescribed.


  • Some patients find relaxation methods or self-hypnosis are helpful in decreasing nausea. Talk with your social worker about audiotapes that have relaxation techniques.
  • Eat small, frequent meals throughout the day instead of three large meals. Nausea is often worse if your stomach is empty.
  • Eat slowly and chew your food completely.
  • Eat foods that are cold or at room temperature. The smell of hot or warm foods might make you more nauseous.
  • Do not mix hot and cold foods, drink liquids rapidly, or eat too fast. These might bring on vomiting.
  • Avoid eating foods that are hard to digest such as spicy foods, fried foods, or other high-fat foods (including rich sweets and sauces).
  • Avoid completing mouth care for 2 hours after eating to prevent nausea.
  • Rest after eating. If you need to lie down, lay on your right side and keep your head elevated about 12 inches above your feet.
  • Instead of drinking beverages with your meals, drink beverages between meals.
  • Drink 6 to 8 eight-ounce glasses of fluid per day to prevent dehydration. Choose cold beverages such as flat soda or flavored drink mixes. You can also choose ice cubes, popsicles, or gelatin.
  • Try to eat more food at a time of day when you feel less nauseous. If you feel nauseous when you first wake up, keep a box of crackers on your night stand and eat a few before getting out of bed. Or, try eating a high-protein snack such as lean meat or cheese before going to bed (protein takes longer to digest).
  • If your healthcare provider prescribes an anti-nausea medicine for you, take it ½ hour to 1 hour before eating.
  • After every episode of vomiting, gargle with a baking soda solution (1 teaspoon of baking soda in 8 ounces of warm water) to cleanse your mouth.
  • Tell your healthcare providers immediately if your nausea causes vomiting that is persistent or severe (if you can't keep fluid or foods down on a continual basis). Persistent vomiting can cause dehydration.


Persistent (ongoing) vomiting and diarrhea cause the body to lose large amounts of water and nutrients. If you are vomiting or having diarrhea more than three times a day and you are not drinking enough fluids, you could become dehydrated. Dehydration is the loss of water from body tissues, and it disturbs the balance of essential substances in your body. Dehydration can cause serious complications if it is not treated.


  • When you are in the hospital, you will receive intravenous fluids.
  • When you are an outpatient, please tell your healthcare provider if you are vomiting persistently or have persistent diarrhea and experience any of these signs of dehydration:
    • Dark urine
    • Small amount of urine
    • Rapid heart rate
    • Headaches
    • Flushed or dry skin
    • Coated tongue
    • Irritability and confusion
    • Dizziness with position changes

Loss of appetite

Feeling nauseous from your chemotherapy or radiation might cause you to lose your appetite. It is important to make an effort to continue good nutritional practices even if you don't feel like eating. Eating balanced, nutritious meals provides you with the energy you need and fuel for your body to recover from your treatment, maintain or gain weight, and to help fight infections.


  • During your hospital stay, you might be unable to eat a well-balanced diet due to nausea, vomiting, mouth sores or loss of appetite. If these side effects prevent you from maintaining proper nutrition, your doctor might want to give you intravenous nutrition, depending on your specific nutritional deficiencies.
  • After you are discharged from the hospital, you might continue to have side effects from your treatment (such as decreased appetite, taste changes, mouth sores, dry mouth, or diarrhea). These side effects might prevent you from trying to maintain good nutrition. Over time, many of these problems will improve.

Here are some suggestions to increase your appetite:

  • Eat small, frequent meals or snacks from 6 to 8 times a day.
  • Drink beverages after meals instead of before or during a meal so you do not feel as full.
  • Try to eat more protein and fat and fewer simple sugars. Eggs, fish, and high-protein puddings will provide you with high nutritional content and high protein in small portions. Custards, peanut butter, ice cream, yogurt, peas, beans, and nuts are also high in protein.
  • Don’t waste your energy eating foods that provide little or no nutritional value (such as potato chips, candy, colas, and other snack foods).

Dry mouth

Having a dry mouth is a possible side effect of chemotherapy or radiation therapy.


  • Rinse your mouth with water before meals.
  • Chew your food completely. Sip liquids frequently while eating to keep food moist and to help with swallowing.
  • Drink 6 to 8 eight-ounce glasses of fluid per day.
  • Gargle with club soda or add lemon or lime to water to thin saliva.
  • Try to eat soft foods with sauces, dressings, broths, sour cream, or gravies to make the food easier to swallow.
  • Try dunking your foods, such as bread, into soups to moisten them.
  • Suck on ice chips or sugar-free gum or candies to keep your mouth moist.
  • Liquid nutritional drinks might be helpful when your mouth is most dry.
  • Artificial saliva and Biotene® products might relieve a dry mouth. Ask your healthcare provider for more information.

Mouth sores

Mouth sores are common after chemotherapy. They can make it difficult to eat and drink. You will be instructed on how to perform daily mouth care. It is important to perform this mouth care as instructed. The healthier you can keep your mouth, the less likely an infection will occur.


To prevent mouth sores:

  • In the hospital, you will be given mouth care products and instructions on how to use them. You will use two types of mouth rinses daily to keep your mouth clean. You are expected to perform your mouth care independently several times a day. 
  • Do not use commercial mouthwashes or lozenges.
  • Patients can brush their teeth after each meal with a small, soft toothbrush and fluoride toothpaste.
  • When home, prepare a gargle by dissolving ¼ teaspoon each of salt and baking soda into 8 ounces of warm water. Rinse your mouth and gargle with this solution at least 4 to 6 times a day, especially after meals and before going to bed.
  • Use dental floss daily, if allowed by your doctor.

If mouth sores develop:

  • If you are able to eat, eat slowly. Cut your food into small pieces and chew it completely.
  • Eat foods that are warm or at room temperature. Avoid hot foods and drinks.
  • Eat soft foods. A soft diet can be prescribed for you, if necessary. Talk to your healthcare provider about a soft diet.
  • Liquid nutritional drinks might be helpful when you have mouth sores.
  • Avoid crunchy foods such as potato chips and nuts.
  • Drink liquids through a straw to make swallowing easier.
  • Do not talk with food in your mouth.
  • Avoid eating or drinking acidic foods and beverages such as tomatoes, oranges, grapefruits, and their juices. Instead, try nectars and imitation fruit drinks with vitamin C.
  • Avoid carbonated beverages.
  • If you are unable to eat due to your mouth sores, your healthcare providers will monitor you nutritional status very closely.
  • You will be given pain medicines intravenously to control or decrease the discomfort caused by the mouth sores while you are in the hospital.

Skin rash

A skin rash or other irritation might occur because of chemotherapy, an allergic reaction to a medicine or from an infection. A skin biopsy might be required to diagnose your skin rash. In this procedure, a small sample of skin is removed and examined under a microscope.

Most skin rashes improve but require time for healing.


  • Gently cleanse the affected area using lukewarm water and mild soap. Do not rub your skin. Pat your skin dry with a soft towel.
  • Do not scratch or rub the affected area.
  • Do not apply any ointment, cream, lotion, or powder to the affected area unless it has been prescribed.
  • Do not apply cosmetics, shaving lotions, perfumes, or deodorants on the affected area. Use only an electric razor if you need to shave within the affected area.
  • Do not wear tight-fitting clothing or clothes made from harsh fabrics such as wool or corduroy. These fabrics can irritate the skin. Instead, choose clothes made from natural fibers such as cotton.
  • Do not apply medical tape or bandages to the affected area unless you are told to do so by your healthcare provider.
  • Do not expose the affected area to extreme heat or cold. Avoid using an electric heating pad, hot water bottle, or ice pack.
  • Do not expose the affected area to direct sunlight. Sun exposure might intensify your skin reaction and lead to severe sunburn. Wear a large-brimmed hat or protective clothing to minimize sun exposure. Choose a sun block/sunscreen of SPF 30 or higher. Continue to protect yourself from the sun even after your course of treatment has been completed.

Hair loss

Hair follicles are very sensitive to radiation and chemotherapy. Both of these treatments cause hair loss. Hair loss might be temporary or permanent. If your hair loss is temporary, it might start to re-grow about 3 to 6 months after your transplant. You might notice that when your hair begins to re-grow, the texture or color is different than before.


  • This side effect can be very upsetting. Talk to your nurse or social worker about wearing scarves, hats or a wig.
  • Ask about the "Look Good Feel Better" program, which was established by the Personal Care Products Council. This program helps women learn how to manage their appearance-related side effects of cancer treatment.
  • Avoid frequent shampooing. Use a mild shampoo (such as baby shampoo) without any perfumes.
  • Wash your scalp with warm water. Avoid rubbing and do not scratch. Pat dry with a soft towel.
  • Avoid excessively combing or brushing your hair.
  • Avoid using hair spray, oils or creams.
  • Avoid using heat sources on your hair (including hair dryers, rollers, or curling irons).
  • Do not perm or color your hair. Ask your healthcare provider when you can go back to coloring or perming your hair.
  • Protect your head from the sun, cold, and wind by wearing a head covering (such as a cap, turban, scarf, or hat made of cotton or a cotton blend).


Everyone has a different level of energy, so cancer treatment will affect each patient differently. Many patients might require a full year to recover physically and psychologically from their treatment. Even after that, life might not return to the “normal” you had experienced before your cancer. You might find that you need to permanently change your lifestyle to prevent fatigue, avoid infections, and cope with the long-term effects of treatment.

During your recovery, you will feel fatigued and weak. You will also have a decreased appetite. It will take some time to regain your strength and ability to participate in daily activities. Each person's recovery varies. You might find that it takes several weeks to many months to resume your daily activities.

The time following your treatment is a time of cell recovery and re-growth of cells in your mouth, stomach, intestines, hair and muscles. This growth requires calories and energy, and might explain why you feel more tired than you anticipated.


  • Evaluate your level of energy. Think of your personal energy stores as a “bank.” Deposits and withdrawals have to be made over the course of the day or the week to balance energy conservation, restoration and expenditure.
    Keep a diary for one week to identify the time of day when you are either most fatigued or have the most energy. Note what you think might be contributing factors.
  • Be alert to your personal warning signs of fatigue. Fatigue warning signs might include tired eyes, tired legs, whole-body tiredness, stiff shoulders, decreased energy or a lack of energy, inability to concentrate, weakness or malaise, boredom or lack of motivation, sleepiness, increased irritability, nervousness, anxiety or impatience.
  • Plan ahead, organize and prioritize your daily activities. Change storage of items to reduce trips or reaching. Decide which activities are important to you, and delegate other tasks/activities when needed. Combine activities and simplify details.
  • Schedule rest. Balance periods of rest and work. Rest before you become fatigued. Frequent, short rests are beneficial.
  • Pace yourself. A moderate pace is better than rushing through activities.
  • Exercise daily. Walking is an excellent way for you to regain your strength and stamina.
  • Eat a well balanced, nutritious diet.
  • Manage stress. Managing stress can play an important role in combating fatigue. Adjust your expectations and ask others for support and help.
  • Talk to your healthcare providers. Although fatigue is a common, and often expected, side effect of cancer and its treatments, mention your concerns to your healthcare providers. There are times when fatigue might indicate an underlying medical problem. Other times, there might be medical interventions to assist in controlling some of the causes of fatigue. Finally, there might be suggestions that are more specific to your situation that would help in combating your fatigue.

Be sure to let your doctor or nurse know if you have:

  • Increased shortness of breath with minimal exertion.
  • Uncontrolled pain.
  • Inability to control side effects from treatments (such as nausea, vomiting, diarrhea, or loss of appetite).
  • Uncontrollable anxiety or nervousness.
  • Ongoing depression.

Insomnia (difficulty sleeping)

Many patients have trouble sleeping during their hospital stay. You might experience insomnia because of discomfort from nausea, mouth sores or other problems. Changes in your daily routine or stress from your personal concerns might also be factors.


  • If necessary, you might be given a prescription medicine to help you fall asleep.
  • Practice relaxation techniques such as mental imagery, deep breathing, reading or listening to calming music.
  • Make sure you are comfortable. Arrange your pillows so you can maintain a comfortable position.
  • Avoid napping too much during the day. At the same time, remember to balance activity with rest.
  • If you feel nervous or anxious, talk to your spouse, partner, or a trusted friend. Get your troubles off your mind. Your social worker can meet with you for individualized counseling and is available to meet with you on your cancer care unit.

Sexual side effects

Chemotherapy and radiation therapy can affect your ability to have children (fertility) in the future. Factors that impact sexual desire — such as hormonal changes, excessive fatigue, cancer pain or treatment, or changes in a person’s self-image — also might affect a person’s ability to have children after cancer treatment.

Some women stop having their menstrual cycles and might benefit from hormone replacement therapy to relieve menopausal symptoms. Talk to your doctor about this treatment option.

Some men might experience a decreased or absent sperm count after cancer treatment.


  • Discuss your concerns about fertility and your desire to have children after treatment with your doctor before you begin cancer treatment.
  • Concerns about being biologically able to have children might be distressing, so it might help to seek counseling with your social worker.
  • It might help to talk about fertility loss and its impact on you and your partner or future partner.
  • Even though infertility (the inability to have children) might occur after cancer treatment, it is still possible to get pregnant, so both men and women should use birth control after treatment. If you do wish to start a family after cancer treatment, talk to your healthcare provider about the timing of a pregnancy after treatment.
  • Some ways to increase your chances of having children after cancer treatment include: sperm banking and cryopreservation (freezing sperm samples so it can later be used to fertilize a woman’s egg); assisted reproduction techniques such as in vitro fertilization (a procedure in which thousands of sperm are placed in a laboratory dish with an egg); and intra-cytoplasmic sperm injection (a procedure in which sperm is injected directly into an egg).
  • Researchers are also looking at new methods of treatment that spare the reproductive system, including hormonal suppression of the reproductive organs, new surgical techniques and tissue transfer.
  • For more information, please refer to the booklet, “Sexuality and Cancer” provided by the American Cancer Society. Also talk to your social worker who can refer you to several agencies or support groups for more information.

Last reviewed by a Cleveland Clinic medical professional on 08/15/2019.


  • Look Good Feel Better. (http://lookgoodfeelbetter.org/helpbetterbegin/) Accessed 8/15/19.
  • National Institutes of Health. National Cancer Institute. Side effects of cancer treatment. (https://www.cancer.gov/about-cancer/treatment/side-effects) Accessed 8/15/19.
  • American Cancer Society. Managing cancer-related side effects. (https://www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects.html) Accessed 8/15/19.

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