Radiotherapy Side Effects:what to expect

This guide is useful if you are:

• Starting radiotherapy and wondering what is normal.
• Feeling tired during treatment.
• Noticing skin soreness in the treated area.
• Having mouth, throat, bowel, bladder, or chest symptoms.
• Worried about symptoms after treatment has ended.
• Caring for someone receiving radiotherapy.

Tiredness and skin changes are common. Other effects depend on the treated area, such as mouth sores for head and neck treatment, loose stool for pelvic treatment, or swallowing pain for chest treatment.

Not always. Some people feel well at first. Side effects often build slowly over the treatment course and may peak shortly after treatment ends.

The skin in the treated area may darken, itch, peel, feel sore, or look sunburnt. Do not scrub it. Ask your team what soap, cream, or dressing is safe for your treatment area.

Radiotherapy can make your body use more energy to repair normal tissues. Cancer, travel, poor sleep, pain, anaemia, chemotherapy, and stress can add to the tiredness.

Call your team if you have fever, severe pain, bleeding, worsening breathlessness, repeated vomiting, dehydration, confusion, new weakness, or symptoms that suddenly become much worse.

Some effects appear months or years later and depend on the body area, dose, age, and other treatments. Examples can include lasting bowel or bladder changes, fertility or sexual changes, lymphoedema, heart or lung effects, bone weakness, memory or hormone changes, and a small risk of a new cancer later. Ask which of these are relevant to your plan and what follow-up you need.

Yes, depending on the area. Treatment near the mouth, throat, chest, stomach, or pelvis can affect appetite, swallowing, taste, nausea, or bowel habits. Tell your team early if eating is becoming difficult.

No. Strong side effects do not prove the treatment is working better. Mild side effects also do not mean treatment is weak.

Do not stop on your own. Tell your team. They may give medicines, skin care, nutrition support, a short break, or another plan depending on the situation.

Many short-term effects improve over a few weeks. Some can take longer. A few late effects can appear months or years later, which is why follow-up matters.

Side effects are not something you have to endure quietly. Report symptoms early, even if they feel small, because simple support can prevent a difficult week from becoming a crisis.

• National Cancer Institute: Radiation Therapy Side Effects
• NHS: Side effects of radiotherapy