External beam radiotherapy directs radiotherapy beams at the cancer from a machine. This is different to internal radiotherapy. Internal radiotherapy means giving radiotherapy to the cancer from inside the body.
This page is about the side effects of external beam radiotherapy.
Everyone is different and the side effects of radiotherapy vary from person to person. You may not have all the effects mentioned.
The side effects you have also depend on:
- how well you are before the radiotherapy
- the dose of radiotherapy
- how long you have it for
Radiotherapy courses for advanced cancer are usually shorter and have less side effects.
Short term side effects
Side effects tend to start a few days after the radiotherapy begins. They gradually get worse during the treatment and can continue to get worse after your treatment ends. But they usually begin to improve 1 or 2 weeks after your treatment ends.
Tiredness and weakness
You might feel tired during your treatment. It tends to get worse as the treatment goes on. You might also feel weak and lack energy. Rest when you need to.
Tiredness can carry on for some weeks or months after the treatment has ended. But it usually improves gradually.
Various things can help you to reduce tiredness and cope with it, such as exercise. Some research has shown that taking gentle exercise can give you more energy. It's important to balance exercise with resting.
Your mouth and throat might get sore. It may be painful to swallow drinks or food. You will have mouth washes to keep your mouth healthy.
You might also have pain or discomfort in your chest, particularly when you swallow.
You can have painkillers to reduce the soreness. Take them half an hour before meals to make eating easier.
Tell your doctor or nurse if you have any pain or discomfort.
During and after treatment, you might have a feeling of a lump in the throat when you swallow. This can make it difficult to swallow solid foods. You might be sick straight after swallowing (regurgitation).
This problem is often at its worst about 10 days to 2 weeks after you finish treatment.
Speech and language therapists play an important role during your treatment. They will help you with swallowing difficulties (dysphagia) and help you eat and drink safely. They can give information to your family or carer on how to support you with swallowing difficulties. A dietitian can also give advice on what to eat when you have swallowing problems.
Tips for eating and drinking:
- Drink about 3 litres of water a day while having treatment.
- Eat soft foods.
- Eat slowly and avoid eating late in the day.
- Drink plenty during and after meals to soften your food.
- Eat small amounts often rather than big meals.
- Try different foods to find out which are easiest to swallow.
- Avoid very hot drinks.
- You can have high calorie drinks to boost your calorie intake if you need them.
You might need to have liquid food through a tube into your nose or stomach if you can’t eat enough. This is called tube feeding.
Feeling or being sick
Feeling or being sick can be severe. It can start a few hours after treatment and last for a few days. You might not feel like eating. Anti sickness injections and tablets can control it. Tell your doctor or nurse if you feel sick. You may need to try different anti sickness medicines to find one that works.
Contact your doctor or nurse straight away if you’ve been sick more than once in a day.
- Avoid eating or preparing food when you feel sick.
- Avoid fried foods, fatty foods or foods with a strong smell.
- Drink plenty of liquid to stop you from getting dehydrated.
- Relaxation techniques help control sickness for some people.
- Ginger can help – try it as crystallised stem ginger, ginger tea or ginger ale.
- Fizzy drinks help some people when they are feeling sick.
Loss of neck and chest hair
Your hair might fall out in the treatment area.
Your voice might get husky or croaky and sound weaker. This can last for a while after your treatment.
This is more likely to happen if your cancer is in the top part of your oesophagus, near to your voice box.
Reddening or darkening of your skin
Your skin might go red or darker in the treatment area. You might also get slight redness or darkening on the other side of your body. This is where the radiotherapy beams leave the body.
The red or darker areas can feel sore. This may start after you have finished treatment. Your radiographers may give you creams to soothe your skin. The soreness usually goes away within 2 to 4 weeks of ending the treatment.
The treatment area might look permanently tanned after your treatment has finished. This is not harmful. Later, you might appear to have very tiny broken veins in the skin called telangiectasia.
Tell the radiotherapy staff if you notice any skin changes.
Radiotherapy can cause many different side effects, such as tiredness. The side effects you get will depend on the area you're having treatment to but there are some general side effects you might experience regardless of where your cancer is. This video is about the side effects you might have when having radiotherapy to the chest.
On screen text: Difficulty swallowing
Martin (Radiographer): Radiotherapy can irritate the lining of your oesophagus, also known as your food pipe, which can cause soreness and swelling and make it more difficult to swallow.
David: After about two weeks it started to get more difficult to swallow. The more it progressed, the worse it got and ended up couldn't eat anything solid at all so it was virtually down to liquids.
Laurel: I wasn't physically able to swallow anything whatsoever and that was quite challenging because I was thirsty and I was hungry, but, you know, nothing was happening.
Martin (Radiographer): Eating foods which are softer and easier to swallow can be helpful. Things such as soup and porridge or mashed potatoes.
Laurel: Yoghurt or custard were easier because I don't need to chew on anything.
David: Soups, trifles, tiramisus. It's down to trial and error and keep trying to eat what you can because you really have to keep your body up to scratch.
Martin (Radiographer): I'd recommend avoiding very spicy foods and avoiding foods which are very hot or very cold.
Laurel: Spicy food, definitely avoid the peppers and stuff like that.
Martin (Radiographer): For chest radiotherapy, we would recommend that you avoid alcohol as this can cause more irritation in the area we're treating.
Laurel: I had a dietitian and either on the phone or they'd pop in.
David: So they noticed that my weight was coming down so they got a dietitian in and she prescribed all these protein drinks.
Martin (Radiographer): You can replace the calories by swapping foods for high calorie alternatives, or your dietitian can recommend high calorie drinks and food supplements. If you're experiencing pain or heartburn during treatment, speak to your team and they can prescribe medication that can help with that.
On screen text:
- Try different foods to find out which are easiest to swallow
- Avoid eating foods that may irritate your throat
- Avoid smoking and alcohol, particularly spirits
- You might need high calorie drinks to boost your calorie intake
- Drink lots of water
- Let your team know if you need painkillers
- Ask to see a dietitian
On screen text: Feeling or being sick
Laurel: Yes, being sick was one of the worst things happening.
David: I was just constantly being sick. I would have my porridge in the morning, wait a couple of minutes and it would be up again so it was just one of these things.
Martin (Radiographer): What you eat and drink can affect how sick you feel during treatment. You can drink fizzy drinks and eat ginger, which can help reduce sickness and we'd recommend avoiding fatty foods or big heavy meals, which can make you feel more sick.
Laurel: But I didn't realise, okay, you can get medication for the anti-sickness until the medical team realises that's what was needed. It's helped me slowing not being sick as often as I would have done because a lot of things I would just be gagging.
Martin (Radiographer): If you are having problems eating and drinking during your treatment, there are dietitians available which can help you.
On screen text:
- Your doctor can prescribe anti sickness medication
- Relaxation techniques such as mindfulness and visualisation might help
- Avoid certain foods
- Eating a few hours before treatment can help
- Drink lots of liquid, taking small sips slowly throughout the day
- See a dietitian for advice – there is help available
On screen text: Shortness of breath
Martin (Radiographer): Having radiotherapy to the chest can affect your breathing. This may come on about two weeks after treatment begins and will continue throughout the rest of treatment. Once you've finished treatment, the breathlessness may continue for a couple of weeks, but then recovers after that. Depending on your diagnosis and treatment you may experience long term breathing problems and your doctor will discuss that with you before you start treatment.
David: So I've been constantly shortness of breath and I take inhalers twice a day now. I just have to be careful in what I do. I can walk for miles on the flat but as soon as an incline, that's when I start to get short of breath. I go out walking or cycling everyday, so that's just a constant to try and keep it going.
Martin (Radiographer): If you are experiencing shortness of breath, we would recommend speaking to your team as soon as you notice it, just to make sure there isn't something else going on, such as an infection or blood clots.
On screen text:
- Shortness of breath can happen during and after radiotherapy
- It usually improves after treatment finishes
- It can continue long term
- Always let your specialist or radiographer know if you are short of breath
If you're experiencing a side effect that hasn't been covered in this video, you can find more information on the Cancer Research UK website.
On screen text: For more information go to: cruk.org/radiotherapy/side-effects
Long term side effects
Most side effects gradually go away in the weeks or months after treatment. But some side effects can continue. Or you might notice some that begin months or years later.
There are things you can do to deal with any effects that you have.
A cough and breathlessness happen in some people who have radiotherapy to the chest area but this is not common. The problems are due to changes in the lung tissue called chronic radiation pneumonitis. They might start many months or a few years after treatment.
Let your doctor know if you notice any changes in your breathing or if you cough up a lot of mucus.
You might have regular tests to check how well your lungs work. Treatment with steroids or other medicines can help you to breathe more easily.
Narrowing of the food pipe
Rarely, your food pipe might become narrower and less stretchy over some months or years. This is called an oesophageal stricture. It can make it difficult for you to swallow.
If you develop a stricture, your doctor can stretch the food pipe slightly. They call this oesophageal dilatation. Stretching the food pipe opens it up again so that you can swallow food and drink more easily.
You have medicine to make you sleepy (sedation). Your doctor puts a tube called an endoscope down your throat. It has an area on it called a balloon. Your doctor expands the balloon to widen the food pipe. They repeat this a few times until the narrowing has gone.
You might need to have this repeated if the narrowing happens again.
Side effects if you have chemotherapy with radiotherapy
Chemotherapy combined with radiotherapy can make some side effects worse. Combining these treatments is called chemoradiotherapy.