Managing Side Effects

Talk with your health care team about possible side effects before beginning treatment and during treatment. Not everyone experiences the same side effects, nor are side effects experienced in the same way.

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Here are common side effects from colorectal cancer treatment.

Side Effects Mini Magazine

This Mini Magazine is written to help you identify common physical side effects that CRC survivors face and provide useful tips for managing them.


Cancer-related fatigue is one of the most common side effects experienced by cancer patients. There are many reasons for fatigue. Tell your doctor about your fatigue as they may want to check blood tests to evaluate for causes of fatigue.

If you feel extremely tired, weary, exhausted or worn out – there are things you can do to regain energy and manage the energy you have.

  • Plan your activities at the time of day when you have the most energy
  • Exercise
  • Take short naps during the day when needed (but not in the late afternoon) 
  • Aim to sleep at least 8 hours at night
  • Eat healthy foods
  • Use relaxation techniques like meditation or yoga to reduce stress

Increased Risk of Infection / Fever

Chemotherapy can decrease your white blood cell count, which increases your risk for infection. Infections can land you in the hospital, and may be life-threatening.

A fever is sign of infection. Take your temperature anytime you feel warm and contact your health care team if your temperature is above 100.5 F so they can evaluate your need for further medical assistance and potentially for antibiotics.


Signs of diarrhea include frequent bowel movements that are soft, loose, or watery. It can result from chemotherapy treatments, colon surgery, radiation treatment, infections, or from your diet.

Abdominal cramping is an early sign that diarrhea is complicated and needs aggressive treatment. Contact your doctor immediately if you experience abdominal cramping.

If you are experiencing diarrhea, tell your doctor immediately. Medications can be prescribed and other strategies can help. If diarrhea doesn’t improve after 24 to 48 hours, or it gets worse, contact your doctor.


Signs and Symptoms

  • Passing fewer than 3 stools per week
  • Having very hard stools
  • Feeling as though something is blocking the stool
  • *Symptoms lasting more than 3-months is considered chronic

Talk to your doctor to learn more about your symptoms. Management of constipation is often a combination of lifestyle changes plus a laxative or stool softener. 

Unintentional Appetite and Weight Loss (Cachexia)

Cachexia is a term to describe a complex, life-threatening metabolic condition that can cause unintentional weight loss, loss of appetite, muscle wasting, and fatigue. It is often experienced along with certain chronic illnesses, such as colorectal cancer (CRC) —and can make this condition even more difficult to treat.

Most patients and caregivers have never heard the term cachexia. The first thing is to recognize what it is and is not. It is not starvation. Cachexia is a syndrome in which your metabolism is increased. You lose your appetite, leading to loss of weight, muscle, and quality of life, as well as increased toxicity and poor survival. Cachexia describes a phenomenon in multiple disease types, but we often talk about it most frequently in cancer. 

Mouth Sores (Mucositis)

Mouth sores are a common side effect of 5-FU. They are painful and can make eating and swallowing difficult or impossible.

Cooling the tissues of the mouth and throat with ice chips before and during administration of chemo helps to prevent mouth sores. Popsicles can help too. However, avoid ice if your treatment includes oxaliplatin.

If your doctor suggests a “magic mouthwash” may help, they will write out the recommended ingredients, and the amount of each ingredient, for you. Antibiotics may be required if sores become infected.

High Blood Pressure

If you’re taking bevacizumab, aflibercept and regorafenib, you may experience high blood pressure, which is routinely treated with appropriate medication.

Treatment may be paused if blood pressure increases too much.


Symptoms of neuropathy include numbness or tingling in your hands or feet, a loss of sensation, shooting pain, loss of balance, aching muscles, problems with finger dexterity, and forgetfulness. A unique symptom you may experience with neuropathy is an extreme sensitivity to cold.

Oxaliplatin, a drug used in the FOLFOX chemotherapy treatment, is known to cause acute or chronic nerve damage.

  • Acute oxaliplatin-induced neuropathy – begins shortly after an infusion of oxaliplatin and gets better within a few days triggered by eating, drinking, or touching something cold or breathing cold air.
  • Chronic peripheral neuropathy – the risk of a longer-lasting sensory neuropathy in your hands and feet increases as the amount of chemotherapy increases in your body. Symptoms may take 18 months to 2 years to go away completely. It is important to let your doctor know if symptoms last beyond a few days after treatment.

To Manage Neuropathy

  • Use gloves, warm socks, and scarves
  • Eat room temperature food (not cold)
  • Avoid excessive air-conditioning 
  • Use handrails and avoid clutter that may cause you to stumble or trip
  • Protect your hands when getting items out of the refrigerator

Be prepared for your first oxaliplatin treatments by wearing gloves, a shawl or blanket, warm socks, and avoiding cold foods/drinks.

Hand-Foot Syndrome

Hand-foot syndrome can occur with some types of chemotherapy, like 5-FU, capecitabine or regorafenib. Symptoms include red, cracked, or peeling skin. This condition is not life-threatening and it gets better once you stop taking the drugs.

Tips to manage:

  • Petroleum jelly, over-the-counter moisturizing creams, or prescription ointments may help healing
  • Some patients find relief from petroleum jelly on the skin under white cotton gloves or socks overnight 
  • If you use petroleum jelly or other moisturizers, be sure to avoid infection by thoroughly cleansing the area the next morning.
  • Avoid long exposure of feet and hands to hot water (like washing dishes or long showers)


Targeted therapies tend to cause skin toxicity, or rash, that can be painful and itchy, or cause a burning, tingling sensation. Your doctor may prescribe a medicated cream to control itching and ease discomfort, or an antibiotic if infection becomes a concern. You might be referred to a dermatologist. If the rash becomes intolerable, you and your doctor may decide to lower your treatment dose. Rash related to the oral targeted therapy regorafenib, may also cause an itchy rash. Talk with your doctor if this happens to see if specific creams or lotions can help.

Wound Healing

Bevacizumab, aflibercept and regorafenib can slow the healing of wounds, so these drugs should be stopped at least two weeks before surgery.

Fecal Incontinence and Adhesions (Rectal cancer)

Radiation treatments can lead to redness and skin irritation. Ask your radiation oncologist for creams to soothe burns.

More serious irritation of rectal tissues can cause diarrhea, rectal bleeding, painful bowel movements, incontinence, or bladder irritation causing frequent urination, blood in the urine, or burning during urination. If you experience these side effects, consult your doctor.

Fecal incontinence is the inability to control your bowel movements. This is a side effect that could result from colorectal cancer treatment. View our side effects resources for more information on diet suggestions for how to manage, and ask your doctor about pelvic floor strengthening exercises.

Chemo Brain

It is estimated that one in five people who take chemotherapy for cancer experience “chemo-brain.” This is a side effect described as a hazy experience with symptoms such as forgetfulness, difficulty finding the right words and difficulty multi-tasking or concentrating. Some regain mental clarity over time, others remain a bit less sharp.

For more on chemo-brain, visit:

Distress and Mental Health

Treatment for colorectal cancer can often lead to distress and anxiety, and even depression. It is important to manage the psychosocial side effects in addition to the physical side effects and consider distress screening.

Ask your treatment team to connect you with a social worker, psychologist, or other mental health professional who has experience working with cancer patients. This will be extremely useful as you move through cancer care and survivorship.

  • To get started, call the Fight CRC Resources line at 1-877-427-2111 from 9 a.m. – 9 p.m. ET Monday through Friday. The call line is available in English and Spanish.

Check out this Cancer and Mental Health support resource from Georgetown University’s School of Nursing & Health Studies.

When Should You Call the Doctor?

Often times we want to bear through discomfort during treatment – with the mindset “no pain no gain.” However, it’s important to know when to seek medical attention. Although rare, there are instances when patients develop severe or life-threatening toxicities within four days of receiving treatment of 5-FU or capecitabine. Side effects that include the following require a call to the doctor or the ER:

  • Altered mental state or coma
  • Irregular heartbeat, heart attack or other cardiac symptoms
  • Unusually severe GI pain and diarrhea  
  • Fever over 100.5 degrees F
  • Any unusual side effects that your treatment team did not tell you about

If your side effects are severe – call your doctor. There are medications like uridine triacetate (Vistogard ®), that can increase your chances of recovery. Pay attention to your side effects. Track them diligently and report to your doctor. If you have side effects that are severe or unexpected, call your doctor.