Chemotherapy can cause several side effects. There are various things people should avoid to minimize these effects, including smoking and eating certain foods.

This article will explore things a person should avoid during chemotherapy. It will also explore recommendations regarding things to do and precautions to take while undergoing chemotherapy.

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Chemotherapy not only targets the rapidly-growing cancer cells but also healthy, rapidly-growing cells in the body. These include the cells that line the intestines and mouth, and the hair follicles.

Because of this, a person undergoing chemotherapy may experience side effects.

Here are 11 things a person can avoid during chemotherapy to minimize side effects and ensure the treatment is effective:

1. Foods that affect CYP enzymes

Cytochrome P450 (CYP) enzymes are molecules that promote the metabolism and absorption of chemotherapy drugs into the blood.

Certain foods can inhibit the function of chemotherapy drugs. They include:

  • grapefruits, including their juice
  • Seville oranges, including their juice
  • St. John’s Wort

2. Overexertion

Some of the common effects of chemotherapy include fatigue, nausea, and mood changes.

For this reason, a person should avoid activities that are mentally or physically taxing. This includes strenuous work or exercise.

3. Interacting with people who have infections

Some chemotherapy treatments can increase the risk of infection.

There will be points during chemotherapy treatment cycles where a person’s number of white blood cells is lower than usual. These cells are responsible for fighting infections.

During these times, it is important that a person minimizes their risk of infection. This includes avoiding contact with people that may have active infections.

4. Smoking

A person should avoid smoking during chemotherapy, as tobacco and cigarette smoke can lead to unwanted effects.

Smoking may result in hypoxia, which is a lack of oxygen, in certain areas of the body. Hypoxia in cancer tumors may reduce the effectiveness of chemotherapy.

Cigarettes can also worsen the side effects of chemotherapy. A 2011 study found that patients receiving chemotherapy who smoked reported a higher symptom burden during the chemotherapy and a higher symptom burden at their 6 month follow-up.

Smoking may also have an effect on drug absorption. A 2014 review found that smokers receiving a chemotherapy drug needed higher doses of the drug to be effective compared to non-smokers.

5. Drinking alcohol

Alcohol, even in small amounts, can worsen the side effects of chemotherapy, such as a dry and sore mouth.

Alcohol may also interact with chemotherapy drugs, which may increase the risk of negative side effects. A person should avoid drinking alcohol heavily or frequently during chemotherapy.

6. Undercooked or raw food

Undercooked and raw food may contain infection-causing germs. Because cancer and chemotherapy weaken the body’s immune system, a person undergoing chemotherapy may find it harder to fight such infections.

Examples of raw or undercooked foods to avoid include:

  • raw fish or shellfish such as sushi and oysters
  • raw nuts
  • moldy cheeses such as blue cheese
  • raw or soft-cooked eggs
  • food from bulk bins
  • fresh salsas and salad dressings
  • raw honey

7. Spicy and acidic food

Chemotherapy can cause sores to form in the mouth. This is because treatment also affects rapidly-growing cells in the lining of the mouth and lips, not just the cancer cells.

It is best to avoid spicy and acidic foods that may cause pain when the mouth is sore. These include:

  • curries
  • chili peppers
  • hot sauces
  • ketchup
  • tomatoes

8. Hard food

A person undergoing chemotherapy who has mouth sores may want to avoid hard and sharp foods that may be difficult to chew and swallow or that may cause more pain in the mouth. These include:

  • crackers
  • biscuits and cookies
  • potato chips
  • granola

9. Vitamins and supplements

There is limited clinical evidence regarding the effectiveness of vitamins and herbal supplements in the treatment of cancer.

However, some vitamins may affect the efficacy of chemotherapy treatment. A 2019 study investigating breast cancer treatments found taking vitamins, such as A, C, and B12, during chemotherapy was associated with significantly poorer outcomes.

10. Ultraviolet (UV) Light

Some of the side effects of chemotherapy include dry, itchy, red, and peeling skin. Chemotherapy may cause a person’s skin to become more sensitive to sunlight and they also may develop minor rashes.

For these reasons, a person undergoing chemotherapy should avoid prolonged exposure to sunlight and avoid using tanning beds.

11. Probiotics

Probiotics are products that contain live bacteria and yeast. These bacteria may be beneficial in fighting bad bacteria and aiding in digestive and bowel function.

However, a person undergoing chemotherapy should avoid probiotics due to their weakened immune system. Products that may contain probiotics include:

  • yogurt
  • miso
  • sauerkraut
  • cottage cheese
  • probiotic capsules, pills, and powders

There are also things that a person can do while undergoing chemotherapy to mitigate the side effects of treatment.

To help mitigate fatigue, which is one of the common side effects of chemotherapy, a person should consider:

  • Having someone drive them to and from their chemotherapy appointments.
  • Requesting reduced hours at work.
  • Organizing childcare for the day of and the day after a chemotherapy appointment.
  • Setting time aside to rest the day of and after a chemotherapy appointment.

A person can minimize the risk of getting infections during chemotherapy by:

  • Washing their hands thoroughly with soap and warm water, especially after using the bathroom and before and after eating.
  • Carrying a bottle of alcohol-based hand sanitizer.
  • Avoiding large crowds and wear a mask if needed.
  • Getting a flu shot before winter.

A common side effect of chemotherapy is loss of appetite and sensitivity to certain types of food and drink. A person can take the following precautions to mitigate these side effects:

  • Thoroughly scrubbing and washing all raw fruits and vegetables.
  • Drinking at least 8-12 cups of liquid every day to prevent dehydration.
  • Going on short walks every day to stay active, as this may increase appetite.
  • Focusing on eating a lot of protein and calories to maintain strength.
  • Washing all kitchen utensils and countertops before and after use.
  • Cooking all food to a sufficient temperature.
  • Eating a higher number of smaller meals, rather than three large meals a day.

A person’s skin can become more sensitive to UV light during chemotherapy. A person can take the following precautions:

  • Moisturizing the skin to prevent itchiness and dryness.
  • Wearing and carrying sunscreen to protect the skin from UV light.
  • Using soaps that are gentle on the skin.
  • Wearing loose-fitting clothes and wearing a hat when in the sun.

As smoking can have detrimental effects on chemotherapy, it is essential that a person give up smoking before chemotherapy and maintain this even after chemotherapy has ended.

Click here to learn tips on how to give up smoking.

Chemotherapy treatment can be physically and mentally taxing. If a person is finding it hard to cope or needs extra help, resources and services are available.

The Organizations that Offer Cancer Support Services database from the National Cancer Institute lists cancer support services, including organizations that offer financial assistance, support groups, and counselors.

People can also call The National Cancer Institute at 1-800-422-6237 to receive more information on organizations that offer assistance.

The American Cancer Society has many services, including a 24/7 helpline at 1-800-227-2345, transportation to appointments, and a cancer survivors network.

Chemotherapy is a treatment option for cancer. Chemotherapy drugs target cancer cells which stop or slow their growth.

A person undergoing chemotherapy should avoid eating undercooked or raw food, interacting with actively infectious people, overexerting themselves, and consuming too much alcohol.

There are also things that a person can do to minimize risks during chemotherapy. This includes practicing good hygiene, such as hand-washing, to minimize the risk of infection.

Support options are available for people undergoing chemotherapy, such as dedicated support groups, hotlines, and counselors.