Eating Problems Caused by Cancer Treatments

Many cancer treatments can cause side effects that make it hard to eat or drink. Learn what problems you might have from your treatment.

Some cancer treatments can affect digesti. Any side effect that impacts your mouth, esophagus, stomach, small intestine, pancreas, colon, or rectum can make it harder to get the food and liquids you need.

Always tell your cancer care team about any problems you’re having. Things can be done to treat the problem or keep it from getting worse.

Surgery

Some surgery (for example, on your mouth, esophagus, and stomach) can affect your ability to eat and drink. Other surgery (on your intestines, liver, gallbladder, and pancreas) can affect your body’s ability to use certain nutrients.

Side effects from general anesthesia can add to these problems. This can make it harder for you to get the extra calories and protein you need to heal after surgery.

Some side effects from surgery that can make it hard to eat and drink include:

• Fatigue
• Nausea and vomiting
• Pain
• Sore throat
• Swallowing problems
• Weight changes

Eating and drinking as soon as you’re allowed after surgery might decrease some side effects. Getting out of bed and moving around after surgery can also help. Doing these things can also help your bowels start moving more quickly and let you go home sooner.

Be sure to talk to your surgeon or cancer care team if you have any problems eating or drinking, or if you are losing weight without trying. They might suggest nutritional supplements or have you work with a registered dietitian (RD).

For more information about surgery as a cancer treatment, see Cancer Surgery.

Radiation therapy

The side effects of radiation depend on the part of your body being treated, the type and total dose of radiation, and the number of treatments.

Side effects can start soon after starting treatment or might not happen for a couple of weeks. Side effects most often get better or go away 3 or 4 weeks after radiation ends, but some may last much longer.

Some side effects from radiation that can make it hard to eat and drink include:

• Diarrhea
• Fatigue
• Mouth dryness or thick saliva
• Mouth sores
• Nausea and vomiting
• Sore throat
• Swallowing problems
• Taste changes

Tell your radiation or cancer care team about any side effects you have so they can help manage them. For example, there are medicines to control nausea and vomiting and others to treat diarrhea.

See How Radiation Therapy Can Affect Different Parts of the Body for more information on its side effects.

Chemotherapy

The side effects you get from chemotherapy (chemo) depend on the kind of chemo, the dose and how it is given. Some side effects start while you are getting the chemo and some don’t happen until days later. Most side effects go away within hours, but some will last longer. If your side effects keep you from eating or drinking as you usually do, ask your cancer care team what can be done to manage them.

Some common side effects from chemo that can make it hard to eat and drink include:

• Appetite changes
• Constipation
• Diarrhea
• Fatigue
• Mouth sores
• Nausea and vomiting
• Sore throat
• Taste and smell changes

It can be helpful to eat something before your chemo starts. Most people find that a light meal or snack an hour or so before chemo works best. If you’ll be there for several hours, plan ahead and bring a small meal or snack in an insulated bag or cooler. Find out if there’s a refrigerator or microwave you can use.

See Chemotherapy for more information on what to expect with chemotherapy.

Immunotherapy and targeted therapies

Less commonly, immunotherapy and targeted therapies sometimes cause side effects that make it harder to eat. These side effects from immunotherapy and targeted therapies include:

• Constipation
• Diarrhea
• Fatigue
• Mouth sores
• Nausea and vomiting

See Immunotherapy and Targeted Therapy for more information on what to expect with these treatments.

If you are losing weight

Losing weight during cancer treatment is normal, but you don’t want to lose too much weight. If you feel tired or weak or are losing more than 3 pounds a week, be sure to let your cancer care team know.

Prompt attention to eating-related side effects can help keep up your weight and energy level and help you feel better.You also might want to try some tips for managing weight loss. 

Special eating plans

If you’re having trouble eating and following a special eating plan for diabetes or another chronic condition, talk to your cancer care team. They can refer you to an RD or help you manage your diet while you’re getting treatment.

For more information, see Managing Cancer-related Side Effects.