Cancer Treatments and Nutrition-related Side Effects

There are a variety of cancer treatments. Each type of treatment may affect your nutrition needs or your ability to eat in a different way. According to the National Institute of Dental and Craniofacial Research, more than one-third of all cancer patients develop complications that affect the mouth. These side effects can be mild to severe and include infection, dry mouth, mouth sores, sensitive gums and jaw pain.

Note: We recommend that you see your dentist for a checkup before starting chemotherapy or radiation. Get a head start on your oral health and address any dental issues. If you have not seen a dentist but you have started treatment, talk to your medical team about the best time for a dental visit.

Chemotherapy is medication that kills cancer cells. It is called a systemic therapy because the chemo travels through the whole body. As a result, you may have side effects in different areas of your body.

General side effects may include fatigue, low blood counts, infection, and hair loss.

Common nutrition-related side effects from chemotherapy may include:

  • Irritation or inflammation of the mouth, tongue, or throat
  • Nausea/vomiting
  • Taste changes (odd taste or lack of taste)
  • Sensitivity to smells
  • Distaste or repulsion for particular foods
  • Acid reflux (stomach acids flows backwards - up into esophagus and causes heartburn)
  • Feeling full from a small amount of food (early satiety)
  • Appetite changes
  • Diarrhea
  • Constipation

Deal with side effects in a timely manner to keep up your nutritional status and to prevent:

  • Unplanned weight loss
  • Dehydration
  • Illness or hospitalization
  • Unplanned breaks in your treatment plan

Talk to your medical team if you have any of these issues.

Ask for a referral to a Roswell Registered Dietitian Nutritionist if you would like:

  • Help with creating a personal meal plan
  • Suggestions for managing side effects that are causing nutrition problems

Nutrition-related side effects from radiation therapy depend upon:

  • The area of the body treated
  • The dose given

Most people will:

  • Feel fatigued
  • Have less of an appetite
  • Have skin changes in the area receiving radiation

In addition, you may have side effects as a result of part of the digestive tract being in the radiated area. Some side effects will last for a short time. Other side effects may begin later or may last longer.

Radiated Area Short-term Side Effects Long-term Side Effects

Head and Neck
Cancers of the brain, mouth, thyroid, or upper esophagus

  • Dry or irritated mouth, tongue, throat, or esophagus
  • Altered sense of taste and/or smell
  • Heartburn
  • Pain when you swallow
  • Thick saliva
  • Jaw stiffness
  • Dry mouth
  • Tooth decay
  • Difficulty or pain with swallowing
  • Altered sense of taste/smell
  • Headaches
  • Jaw stiffness

Upper Body
Breast or lung cancer

  • Irritation of esophagus
  • Nausea, vomiting
  • Cough
  • Tenderness/swelling of irradiated breast
  • Irritation of esophagus
  • Cough
  • Difficulty breathing

Cancers of the lower esophagus, stomach, gallbladder, liver, pancreas, or kidney

  • Irritation of the stomach
  • Nausea, vomiting
  • Diarrhea
  • Lactose intolerance*
  • Irritation of the stomach
  • Nausea, vomiting
  • Diarrhea
  • Lactose Intolerance*

Lower Body/Pelvis
Cancers of the colon, rectum, prostate, ovaries, uterus, cervix, or bladder

  • Diarrhea
  • Abdominal discomfort
  • Changes in urinary frequency, incontinence
  • Diarrhea
  • Abdominal discomfort
  • Painful urination
  • Changes in urinary frequency

* Lactose intolerance is a digestive system sensitivity to the sugar found in milk. It can cause bloating, gas, and abdominal cramps.

As a general rule, your body needs more calories, protein, and nutrients after surgery, to promote healing. Whether you have nutrition-related side effects will depend upon:

  • The site of the surgery
  • Whether any parts of your digestive system were removed or changed during the operation
Area of the Body Surgical Procedure Possible Nutrition-related Side Effects

Head, neck, tongue, or jaw

  • Removal of all or part of the affected area
  • Difficulty chewing/swallowing
  • May need a feeding tube


  • Removal of the affected area with possible reconstruction using muscle from the intestine
  • Narrowing of the esophagus
  • Abdominal cramping
  • Nausea
  • May need a feeding tube


  • Partial or complete removal of the stomach
  • Poor appetite
  • Feeling full quickly
  • Acid reflux
  • Nausea
  • Diarrhea
  • Possible iron, folate, or Vitamin B12 deficiency

Small Intestine

  • Partial removal
  • Reconstruction or opening created outside the body (ileostomy)
  • Abdominal discomfort
  • Poor absorption of nutrients
  • Diarrhea
  • Electrolyte & water loss; dehydration
  • Vitamin B12 deficiency


  • Partial or complete removal
  • Reconstruction
  • Diabetes
  • Frequent, loose bowel movements
  • Indigestion

Large Intestine

  • Partial or complete removal
  • Reconstruction or opening created outside the body (colostomy)
  • Poor absorption of nutrients and water
  • Dehydration
  • Diarrhea

Hormone therapy may be prescribed to treat cancers of the breast, prostate, ovary, or endometrium. Possible side effects include:

  • Hot flashes
  • Nausea/vomiting
  • Bone loss (as a result of androgen deprivation therapy or aromatase therapy)
  • Fluid retention
  • Unplanned weight gain

A nutritious meal plan can help to manage these side effects. Discuss these side effects with your medical team and explore ways to increase your physical activity and maintain your bone health.

Immunotherapy activates your own immune system to fight cancer. Immunotherapy works differently than chemo, and the side effects are different as well. Possible side effects include:

  • Flu-like symptoms such as fever, chills, nausea, vomiting, fatigue, poor appetite
  • Bone and/or joint pain

To get the best nutrition possible while dealing with these symptoms, you may find it easier to have smaller meals and eat more frequently during the day (instead of two or three large meals a day).