Every individual reacts in a different way to treatment be it radiation or any other therapy. Some may not react at all.

The side effects of radiation therapy vary in severity and duration from person to person and depend on:

  • The general health of the patient
  • Type of cancer
  • Location of cancer in the body
  • The dose of radiation given

Low-dose radiation causes no side effects or they may be nominal. Radiation doses prescribed for treating cancer are high. Besides killing the cancer cells and shrinking the tumor, they also kill the adjacent normal healthy cells and tissue. It is the damage to the normal cells that causes the side effects.

Why does radiation therapy cause side effects?

Radiation side effects are caused because of the damage it causes to the normal cells and tissues adjacent to the tumor which also get radiated. Radiation can damage the DNA in our cells.

It’s all about the dose and it decides whether the therapy will be harmless or poison. Small doses which we receive every day from the environment are harmless.

High doses of radiation can cause Acute Radiation Syndrome (ARS) or Cutaneous Radiation Injuries (CRI). They can also lead to the development of cancer later in life.

The advances in research on radiation have succeeded in making radiation more precise. Compared to earlier complications caused by radiation, there has, therefore, been a significant reduction in the severity and duration of the side effects.

The fact remains, however, that some people experience fewer or no side effects while some may have severe adverse effects.

When do the side effects start and how long do they last?

The side effects of radiation on the body usually start during the second or third week after starting treatment and may last for several weeks after the treatment is completed.

Though the healthy cells that are damaged during radiation usually recover within a few months after radiation is over, some people may continue to have side effects without any relief.

Radiation therapy does not kill cancer cells immediately after exposure. It takes days or weeks of treatment before radiation starts to kill the cancer cells. Even after the completion of the radiation treatment, cancer cells keep dying for weeks or months later. The normal cells, too, are affected in a similar manner.

Therefore, at times, side effects may appear months or years after radiation therapy has been completed. These are called late effects. These long-term side effects typically do not cause any severe long-term issues that can cause serious consequences on the patient’s quality of life.

These variations in the side effects depend on:

  • The part of the body that has been radiated
  • Other treatments of cancer you have had
  • Your genetic structure
  • Other environmental factors such as smoking
  • Prescribed dose and schedule of radiation

Usually, most side effects disappear within a few months (usually one to two months) of completing your radiation treatment. Some may linger because the healthy cells that are damaged may take more time to recover.

There are cases where the side effects do not allow you to carry on your daily activities. In such cases, the doctor may stop further radiation for some time, may change the schedule, or may totally change the type of treatment.

Side effects from radiation therapy

Certain side effects of radiation therapy such as fatigue and loss of appetite are common and appear with radiation to any part of the body.

Other radiation therapy side effects you may experience depend on the part of the body that is treated.

Some side effects appear late and may appear months or years after radiation therapy has been stopped.

1. Fatigue and weakness due to radiotherapy

Most people on radiation therapy feel tired and fatigued after a few weeks. Fatigue is a feeling of being exhausted and worn out. The reason for this fatigue is the destruction of normal healthy cells that radiation kills along with the cancer cells.

The fatigue gets worse as the treatment progresses, This is called cumulative fatigue. It usually disappears after 3 to 4 weeks after treatment but in some cases, it may last for 3 months.

2. Loss of appetite due to radiotherapy

Loss of appetite is a common side effect of radiation and is seen throughout the course of radiotherapy. Sometimes, it can continue even after the treatment is completed. For some people, the loss of appetite is so severe that eating anything at all can seem impossible.

3. Effects on the skin over the area that is radiated

During the first two weeks of radiation, your skin that is exposed to radiation becomes red and itchy. The skin rash and pigmentation disappear after stopping treatment.

Three to four weeks later, it may become dry and start peeling. It becomes swollen and may develop sores that are painful and become infected and moist.

Over the long term, the skin may become dark and thin. Most often, the skin changes get better a few weeks after treatment ends. However, there is a permanent loss of elasticity in the affected part of the skin.

4. Side effects of radiation therapy on head and neck

Radiation to the head or neck may cause these side effects:

  • Dryness of mouth
  • Mouth ulcers
  • Swallowing difficulty
  • Stiffness in the jaw
  • Nausea and vomiting
  • Loss of hair on the scalp and face
  • A type of swelling called lymphedema that is caused by the extra collection of lymph fluid in the tissues
  • Tooth damage
  • Loss of cognitive function

5. Side effects on chest

Radiation therapy to the chest may cause these side effects:

  • Difficulty in swallowing food or drinks
  • Dyspnea (shortness of breath)
  • The breast or nipple may become sore
  • The shoulder may become stiff
  • You may experience radiation pneumonitis, symptoms of which include cough, fever, and a feeling of fullness of the chest. This may occur between 2 weeks and 6 months after radiation therapy.
  • Radiation fibrosis can cause permanent lung scars if radiation pneumonitis is left untreated.
  • Increased risk of heart disease

6. Side effects on stomach and abdomen

Radiation therapy to the stomach or abdomen may cause these side effects:

  • Loss of appetite
  • Nausea and vomiting
  • Abdominal cramps
  • Diarrhea

Dietary changes may be necessary to reduce these side effects. Medicines to counter these side effects may also be prescribed. These side effects go away after the radiation is stopped.

7. Side effects caused by radiation to the pelvis

Radiation to the pelvis may cause these side effects:

  • Diarrhea
  • Bleeding per rectum
  • Urinary incontinence (loss of urinary control)
  • Erectile dysfunction (inability to have or maintain an erection)
  • Lowered sperm counts from radiation to the testes or prostate gland, which can lead to infertility
  • Menstrual disorders
  • In women, there may be vaginal itching, burning, and dryness
  • Radiation to both ovaries may lead to infertility in women.
  • Cystitis (inflammation of the urinary bladder)
  • Loss of pubic hair, which grows back after treatment is stopped.

Whatever the side effects of radiotherapy, the life-saving benefits of cancer radiation far outweigh them. Cancer research is showing encouraging improvements in radiation therapy and it is being positively hoped that radiation treatment will not be so fearful for the cancer patient, as it is today.

8. Late side effects of radiation therapy

Some cancer radiation side effects may come months or years after the radiation therapy for cancer is stopped. These include:

How can you reduce the side effects of radiation?

Radiation oncologists are trained not just to dose you with the right amount of radiation for a cure but also to minimize the side effects.

The dose schedule is arrived at to limit the overall radiation exposure to just the right amount to kill the cancer cells while minimizing its effect on the normal healthy cells. Your treating doctor may prescribe medicines to manage these side effects.

You could take a few precautions to help cope with the side effects.

  • Get plenty of rest and good sleep.
  • Follow a balanced diet that is rich in macro and micronutrients. An oncology dietitian can help you to formulate your diet plan.
  • Take care of the skin in the treatment area.
  • Wear loose clothing, especially over the treatment area.
  • Shield the radiated area from the sun, heat, and cold.
  • Finally, there are options to prevent and treat the side effects. This is a supportive part of your general cancer treatment. It is called palliative care.

What is radiation recall?

Radiation recall is a skin rash caused by an acute inflammatory reaction that looks like severe sunburn. It is rare and is triggered when certain precipitating systemic chemotherapy drugs are given during or soon after external-beam radiation therapy. Why it happens is still poorly understood.

The rash is localized to that part of the body that receives radiation. Symptoms may include redness, tenderness, swelling, wet sores, and peeling skin.

Usually, these side effects start soon within days or weeks of radiation therapy. However, they can also appear months or years later after radiation has been stopped.

Treatment is with medications called corticosteroids. Rarely, it may be necessary to stop chemotherapy till the skin heals before continuing it again.