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RADIOtherapy Side Effects Guide

Radiotherapy is a powerful treatment, but it can also affect your body in unexpected ways. This guide helps you prepare for and manage common side effects, so you can feel more confident and supported throughout your treatment journey. At Curo Oncology, we’re here to care for your whole self — body, mind, and spirit.

The side effects of radiation treatment vary from patient to patient. The side effects depend mostly on the radiation dose and the part of your body that is being treated.

Before beginning your treatment, your doctor will discuss the potential side effects of radiation therapy, including how long they may last and their severity. Side effects may be acute or chronic. 

Acute side effects are referred to as “early side effects”. They occur soon after treatment begins and usually disappear within a few weeks of finishing therapy.

Chronic side effects may take months or years to develop and are usually permanent.

The most common early side effects of radiation therapy are fatigue and skin changes. Skin changes result from radiation administered to a treatment site. For example, temporary or permanent hair loss may be a side effect of radiation treatment to the head.

Fortunately, most side effects will go away in time. In the meantime, there are ways to reduce discomfort. Be sure to tell your doctor, nurse, or radiation therapist about any side effects that you notice. They can help you treat the problems and tell you how to lessen the chances that the side effects will come back.

Not necessarily. It depends on which side effects you have and how severe they are.

Many patients can work and enjoy their usual leisure activities while they are having radiation therapy. Others find that they need more rest than usual. Try to continue doing the things you enjoy, as long as you do not become too tired.

Fatigue is the most common symptom reported by cancer patients undergoing radiation therapy. The exact cause of this side effect is not always known. It may be due to the disease or treatment. It may also result from lowered blood count, lack of sleep, pain or poor appetite.

Most patients begin to feel tired after a few weeks of radiation therapy. During radiation therapy, the body uses a lot of energy to heal. You may also feel tired because of the stress related to your illness, daily trips for treatment and the effects of radiation on normal cells. Feelings of weakness or weariness will go away gradually after your treatment is complete.

Tips for Managing Fatigue:

  • Prioritise your energy: Focus on the activities that matter most to you. Let go of tasks that can wait.
  • Plan for rest: Try to get more sleep at night and schedule short rest breaks during the day.
  • Try light activity: Gentle movement, such as walking, may help boost your energy levels.
  • Adjust your work schedule if needed: Some people continue working full-time during treatment, while others reduce their hours or take time off. Do what feels manageable for you.
  • Ask for help: Family and friends can assist with daily tasks like cooking, cleaning, or errands, giving you more time to rest and recover.

Radiotherapy can cause changes to the skin in the area being treated. Your skin may become red, irritated, or appear sunburnt or tanned. Over time, it may also become dry, tight, or flaky.

In some areas, particularly where skin folds (such as under the arms, between the buttocks, or in the groin), you may experience a moist reaction, where the skin becomes sore, weepy, or blistered. This needs extra care, so let your doctor or radiotherapist know straight away if this occurs.

Tips for Caring for Your Skin During Treatment:

  • Use only lukewarm water to wash the treatment area. Avoid soap and gently pat the skin dry with a soft towel.
  • Wear loose-fitting, breathable clothing to avoid irritation.
  • Do not rub, scrub, or scratch the treated skin, especially while bathing.
  • Avoid using any creams, powders, deodorants, perfumes, or lotions on the treatment area during therapy and for a few weeks after.
  • Do not expose the treated skin to sunlight or tanning beds during treatment.
  • Take showers instead of baths to reduce prolonged skin contact with water.
  • After treatment, you may use plain aqueous cream (no added fragrance or colour) or Aloe Vera gel to soothe dry skin, but only with your care team’s approval.

Most skin reactions settle within a few weeks after treatment ends. Some areas may remain slightly darker or more sensitive to the sun long-term, so ongoing care and sun protection are important.

Radiation therapy can cause hair loss (alopecia), but only in the area being treated. For example, if you receive treatment to your hip, you will not lose hair from your head. However, if radiation is directed at your scalp, you may lose hair in that area.

In many cases, hair grows back after treatment is complete, although it may return with a different texture or colour.

Caring for Your Scalp:

  • Your scalp may feel tender after hair loss. Wearing a soft hat, turban, or scarf can help protect and soothe it.
  • Always cover your scalp when outside, as it will be more sensitive to sun exposure. Use a protective scarf or hat.
  • If you plan to wear a wig, consider selecting it early in your treatment so it can be matched to your hair’s natural style and colour.

Hair loss can be an emotional part of treatment. If you’re feeling distressed, talk to your care team — support is available.

Radiation therapy can reduce your appetite and affect how your body digests and absorbs food. This may lead to weight loss, especially if it becomes difficult or painful to chew or swallow. Eating well during treatment is important to help your body heal and maintain strength.

You may lose between 0.5 to 1 kilogram per week during treatment, which is common. A balanced diet with enough calories and protein can help rebuild damaged tissue and support your recovery.

Tips for Maintaining Nutrition:
  • Eat small meals more often: Aim for several small meals or snacks throughout the day, rather than three large meals.
  • Eat when you’re hungry: Don’t wait for a set mealtime. Take advantage of your appetite when it appears.
  • Keep simple, ready-to-eat meals on hand: Store food in the fridge or freezer for when you feel up to eating.
  • Let others help: If friends or family offer to cook for you, say yes, and let them know what you’d enjoy.
  • Keep nutritious snacks nearby: Have easy options ready, like nuts, yoghurt, soft fruits, or smoothies.

High-calorie tips (for small appetites):

  • Add butter, cream, or cheese to your meals
  • Mix cream soups with milk instead of water
  • Use liquid nutritional supplements or shakes
  • Add yoghurt, powdered milk, or honey to drinks
  • Drink eggnog, smoothies, or fortified milkshakes

If you’re not enjoying food:

  • Taste changes are common. Try new flavours, temperatures, and preparation methods
  • Liquid supplements may be easier to tolerate than solids
  • Speak to a dietitian for tailored advice. They can help you maintain weight and comfort

If eating is difficult:

  • Choose soft foods and add sauces or gravies to make chewing and swallowing easier.
  • Avoid dry, rough, or spicy foods if your mouth or throat is sore.
  • Cut food into small pieces and eat slowly.
  • Ask your doctor about medicated mouthwashes or throat treatments to relieve discomfort.

Important:

Always check with your doctor before drinking alcohol, especially if you are receiving treatment to the head, neck, chest, or oesophagus.

Diarrhoea is a possible side effect of radiation therapy, especially when the treatment area includes the abdomen or lower digestive tract. Certain chemotherapy drugs can also cause diarrhoea. If not managed early, severe diarrhoea can lead to dehydration and loss of vital minerals like sodium and potassium, which can become life-threatening.

Prevention is key. If your doctor prescribes anti-diarrhoeal medication, take it exactly as directed, before symptoms become severe.

Important:

Contact your care team immediately if diarrhoea becomes severe, persistent, or is accompanied by dizziness, weakness, or signs of dehydration.

Tips for managing Diarrhoea:

Medications:

Your care team may prescribe anti-diarrhoeal drugs such as:

  • Lomotil, Imodium, Gastron
  • Smecta, Pectin, Kantrexil
  • Buscopan, Colofac
  • Codeine phosphate, Morphine (for severe cases)


Always follow your care team’s advice and alert them if symptoms worsen or persist.

Helpful Hints:

  • Eat small, bland meals at room temperature
  • Begin a low-residue diet from day 1 of radiation therapy
  • Add a pinch of nutmeg to meals (may help calm bowel movement)
  • Consider oral rehydration solutions (e.g. Energade, Game isotonic drinks) if fluid loss is high
  • Drink at least 8 cups (preferably 3 litres) of fluids daily:
    Try water, coconut water, chamomile or ginger tea, rice milk, ginger ale, or diluted nectars like peach, pear, or papaya. Let fizzy drinks go flat before drinking to ease digestion.
Dietary Tips:

Eat more of the following:

  • Soluble fibre foods: plain oatmeal, white rice, ripe bananas, applesauce, canned fruits (no skins), plain pasta, white toast, cream of rice cereal, unsweetened crackers

  • Mild proteins: baked, broiled, or roasted chicken, fish, or lean meats

  • Cooked vegetables: carrots, green beans, spinach, squash, and asparagus tips

  • Dairy alternatives: yoghurt, buttermilk, mild processed cheese, lactose-free supplements (e.g. Ensure)

Foods and Drinks to Avoid:

  • Whole-bran breads and cereals
  • Nuts, seeds, coconut
  • Fried, fatty, or greasy foods
  • Fresh or dried fruits, prune or grape juice
  • Raw vegetables, spicy or heavily seasoned foods
  • Chocolate, caffeine (in tea, coffee, soft drinks)
  • Alcohol and tobacco