Possible side effects of radiotherapy for CUP

When radiotherapy is given to relieve symptoms (palliative radiotherapy), the side effects are usually mild. If you are having radiotherapy to control the cancer, the side effects will depend on the dose and the area being treated.

Skin reactions

Your skin in the treated area may get red, dry, itchy and feel sensitive or sore. Dark skin may get darker. Your nurse or radiographer will give you advice on looking after your skin. If it becomes sore and flaky, let them know. Skin reactions usually settle down 2 to 4 weeks after radiotherapy. Your radiographers will check your skin regularly.

We have more information about caring for your skin.

Tiredness (fatigue)

Not everyone feels tired during radiotherapy treatment but many people do.

Tiredness can continue for weeks to months after your treatment has finished. It can often be made worse by having to travel to hospital each day, or by other treatments such as surgery or chemotherapy.

Some people are able to continue with their day-to-day activities, but others may find they need to rest more.

Managing tiredness

Get plenty of rest but balance this with some gentle exercise, such as short walks. This will give you more energy and help to keep your muscles working. Save some energy for doing the things you enjoy. You can also ask others for help doing chores if these are tiring you out.

We have more information about coping with tiredness (fatigue).

Body-specific side effects

Other side effects will depend on the area of the body being treated.

Stomach and pelvis (lower abdomen)

Radiotherapy to this area may make you feel sick or cause diarrhoea. Your doctor can prescribe medicines to help.

Radiotherapy to the pelvic area can also cause discomfort when you pass urine (cystitis) and a feeling of needing to pass urine more often. If this happens let your doctor or nurse know. Drinking lots of fluids and taking mild painkillers can help.

Radiotherapy to the pelvis can have an effect on your sex life. For men, radiotherapy can make it more difficult to have an erection. For women it can make the vagina narrower, which can make sex uncomfortable. Even though it might feel embarrassing, you can talk about these problems to your nurse or doctor as there are often things that can help. 

We have more information about sexuality and cancer for men and for women. We also have more information about pelvic radiotherapy.


If you have radiotherapy to the chest, you may have difficulty swallowing and a cough. Your doctor can prescribe painkillers to help with this. Eating soft foods will make swallowing easier.

Head and neck

You may have a dry mouth and taste changes, a sore throat, hoarseness or difficulty swallowing. Your doctor can prescribe liquid painkillers, and eating soft foods will make swallowing easier. Your sense of taste will usually gradually return to normal when treatment finishes. We have more information about coping with a dry mouth.


You may feel drowsy, especially towards the end of treatment. Radiotherapy to the brain also causes hair loss, but your hair will usually grow back again a few months after treatment finishes.

Tell your doctor, nurse or radiographer about any side effects you have, as there are often ways they can be reduced. Most side effects improve when your treatment finishes.

Back to Radiotherapy explained

Radiotherapy for CUP

Radiotherapy uses high-energy rays to destroy cancer cells. It aims to treat cancer or relieve symptoms.

Before your radiotherapy

Before you start radiotherapy, your team will explain what your treatment involves and how it may affect you.

Your radiotherapy team

You will meet many different specialists from your radiotherapy team. You may see them before, during and after radiotherapy treatment.

After treatment

It can take time to recover from radiotherapy. Support is there if you have any problems.