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Side Effects of Cancer Treatment

While every cancer journey is different, understanding the common side effects of treatment can help you prepare for the road ahead. Supportive, or palliative care, helps you plan for those side effects, minimizing their impact. At SSM Health, our expert cancer care team will create a customized treatment plan for you.

Before you begin treatment, ask your SSM Health oncologist about what to expect and how to manage your side effects during the process. In addition, nurse navigators are always available to provide support should you have questions or concerns along the way.


Fatigue, or extreme exhaustion, is the most common problem experienced by cancer patients. More than half of our patients experience fatigue during chemotherapy or radiation therapy, and up to 70% of patients with advanced cancer experience fatigue.


Anemia, an abnormally low level of red blood cells (RBCs), is common in people with cancer, especially those receiving chemotherapy. RBCs contain hemoglobin (an iron protein) that carries oxygen to all parts of the body. If the level of RBCs is too low, parts of the body do not receive enough oxygen and cannot work properly. This can leave you feeling tired and weak.

Nausea & Vomiting

Nausea (feeling sick to your stomach) and vomiting (throwing up) may occur in patients receiving chemotherapy and in some patients receiving radiation therapy. Many patients with cancer say they fear nausea and vomiting more than any other side effects of treatment. Your doctor can prescribe anti-nausea medication to minimize this.

Fluid in the Arms or Legs (lymphedema)

The lymphatic system is a series of channels and small sacs that carry lymph, a clear liquid containing protein and cells that fight infection, throughout the body. Lymphedema occurs when the lymphatic system is damaged or blocked and cannot drain properly. This lymph build up causes swelling.

The most common causes of lymphedema include:

  • Surgery to remove the lymph nodes, especially for breast cancer, prostate cancer, or melanoma 
  • Radiation therapy to the lymph nodes
  • Metastatic cancer
  • Bacterial or fungal infection
  • Injury to the lymph nodes
  • Other diseases involving the lymph system

Lymphedema can develop immediately following treatment or may not appear until months or years later.

Hair Loss (alopecia)

Chemotherapy and radiation therapy can damage the hair follicles responsible for hair growth, causing hair loss. Hair loss may occur throughout the body, including the head, face, arms, legs, underarms and pubic area. Hair loss due to treatment is usually temporary and often grows back once treatment has stopped.


Infections occur when harmful bacteria, viruses, or fungi (such as yeast) invade the body, and the immune system is unable to destroy them quickly enough. Patients with cancer are more likely to develop infections because both cancer and its corresponding treatments - particularly chemotherapy and radiation therapy - weaken the immune system. Symptoms of infection include:

  • Fever (temperature of 100.5°F or higher)
  • Chills or sweating
  • Sore throat or sores in the mouth
  • Abdominal pain
  • Pain or burning when urinating or frequent urination
  • Diarrhea or sores around the anus
  • Cough or breathlessness
  • Redness, swelling, or pain, particularly around a cut or wound
  • Unusual vaginal discharge or itching

Contracting an infection during treatment can be life-threatening. Call your doctor immediately if you have any symptoms of an infection.

Menopausal Symptoms in Women

Up to 40% of women undergoing treatment for breast cancer experience menopausal symptoms, including:

  • Hot flashes
  • Night sweats
  • Vaginal dryness, itching, irritation, or discharge
  • Painful sexual intercourse
  • Difficulties with bladder control
  • Depressed feelings
  • Insomnia

Premenopausal women receiving chemotherapy for breast cancer may undergo menopause at an earlier age than traditionally expected.

Mouth Sores (mucositis)

Mucositis is an inflammation of the inside of the mouth and throat, leading to painful ulcers and mouth sores. Radiation to your head and neck, high doses of chemotherapy and the reduced immunity brought on by treatment can all cause mucositis. Let your care team know immediately if you notice any changes in your mouth.

Weight Gain

Although it is more common to lose weight during treatment, some patients with cancer do gain weight. Chemotherapy, steroid medications and hormone therapies can cause weight gain. While slight increases in weight during treatment are generally not problematic, significant weight gain may affect your health and the ability to tolerate certain treatments.

Managing the emotional and physical toll of your treatment through supportive care is one of the most important parts of your cancer care plan. Make an appointment with your SSM Health team to discuss any side effects you’re experiencing. We'll help you find ways to manage them. Know that you are not alone in your fight against cancer- your experienced and compassionate SSM Health Cancer Care team will be there to support you every step of the way.

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