Side effects of pelvic radiotherapy

Pelvic radiotherapy can cause side effects during and after treatment. Your radiographer or nurse will give you advice or medicines to help manage them.

Side effects during pelvic radiotherapy

Pelvic radiotherapy can cause side effects during and after treatment. The side effects you have may depend on:

Having chemotherapy at the same time as radiotherapy is called chemoradiation. This may cause more severe side effects.

Side effects do not usually happen straight away. They may develop during your course of treatment, or in the days or weeks after treatment finishes. After you have finished radiotherapy, side effects may get worse for a time before they get better. Usually, they gradually improve over a few weeks or months after treatment has ended.

Always tell your radiotherapy team or cancer doctor if you have side effects. They can give advice and support to help you cope. You may also find it helpful to read our information about the type of cancer you are having treatment for. This has more detail about your treatment, and the other possible side effects.

Pelvic radiotherapy may mean you will not be able to get pregnant after treatment or be able to make someone pregnant (infertile). Your healthcare team can tell you more. We have more information about cancer treatment and fertility in men and fertility in women.

Pelvic radiotherapy can also cause side effects that last longer or start later after treatment. We have more information about the late effects of pelvic radiotherapy.


Not everyone feels tired during radiotherapy treatment, but many people do. Tiredness (fatigue) can continue for weeks, or a few months after your treatment has finished. You might be more tired if you have to travel to hospital every day, or if you are also recovering from other treatments.

Some people are able to continue with their day-to-day activities. Others might need more rest.

Coping with tiredness

There are things you can do that may help you cope with tiredness. We have more information about coping with tiredness and fatigue.

Effects on the skin

Sometimes, pelvic radiotherapy can cause a skin reaction in the area being treated. This can be uncomfortable, particularly in sensitive areas, such as the anus, vulva, penis, scrotum, either side of the groin or between the buttocks.

Your radiographer or nurse will check your skin regularly and give you advice about managing any reaction. They may give you dressings, or a gel or other products to help. They can also give you painkillers to take, if you need them.

We have more information about skin reactions caused by radiotherapy.

Pelvic radiotherapy may also make your pubic hair fall out. It should start to grow back again within a few weeks after radiotherapy finishes, but it may be thinner. Sometimes, hair loss is permanent.

Skin care

Your radiographer or nurse will explain how to look after your skin during pelvic radiotherapy. They will usually give you advice, including some of the following:

  • Have showers rather than baths if you can. Soaking in a bath can make the skin too moist. When you shower, use a very gentle stream of lukewarm water. If you have a bath, do not use very hot water. Try not to soak in the water for longer than a few minutes.
  • Follow your team’s advice about using soaps, moisturisers, creams and deodorants.
  • Wear loose underwear or shorts made from natural fibres, such as cotton or silk. They should be loose-fitting so they do not rub against the skin. Avoid wearing tights, tight-fitting underpants or trousers.
  • Do not shave, wax or use hair removal creams in the treatment area during radiotherapy. Wait until a few weeks after radiotherapy is over and any skin reaction has healed.
  • Protect the skin of the treated area from the sun for the first year after radiotherapy. You should do this even after any skin reaction has settled. It is best to always wear sunscreen with a high sun protection factor (SPF) of at least 30.
  • If you smoke, try to stop. Smoking can make skin reactions worse.

Bladder side effects

Pelvic radiotherapy can irritate the lining of the bladder. This can cause side effects such as:

Swelling around the urethra

If your treatment involves the prostate or penis, it may also cause swelling around the urethra. This is the tube that carries urine from the bladder, through the prostate, to the opening at the tip of the penis.

This can cause side effects such as:

  • passing urine more often than usual
  • a feeling that you cannot wait when you need to pass urine
  • needing to wait for the flow of urine to begin
  • having a weak flow of urine
  • feeling that you have not fully emptied your bladder.

It is important to contact the hospital straight away if you cannot pass urine at all. This is a rare side effect caused by swelling that closes the urethra completely. This stops urine flowing out of the bladder. It may affect you after brachytherapy for prostate cancer. You may have drugs that reduce the swelling. Or you may have a tube (catheter) put into the bladder for a short time.

Coping with bladder side effects

People often feel embarrassed talking about bladder problems. But if you tell your doctor, radiographer or nurse, they can help and it is usually possible to improve it.

There are drugs that can improve bladder side effects and help you feel more comfortable.

Your team may ask you for a urine sample to check if you have an infection. An infection is a common cause of symptoms and is easy to treat.

Contact the hospital straight away if:

  • your symptoms get worse
  • you have a high temperature
  • you feel you cannot pass urine.

Your team can advise you about coping with any bladder problems. If the problems do not improve within a few weeks, they may arrange tests. Or they may get more advice for you from a continence specialist.

We have more information about coping with bladder problems.

Bowel side effects

Pelvic radiotherapy can cause some of the following side effects:

  • loose stools (poo) or diarrhoea
  • hard stools or constipation
  • needing to empty your bowel (poo) urgently
  • cramping pains in your tummy (abdomen) or back passage (rectum)
  • passing a lot of wind.

Some other, less common side effects are:

  • feeling you need to go to the toilet although your bowel is empty (tenesmus)
  • passing mucus or blood when you empty your bowels
  • bleeding from piles (haemorrhoids)
  • slight soiling of your underwear or some leakage (incontinence).

Bowel side effects usually start to improve about 2 weeks after radiotherapy finishes. Sometimes, they may take a few months to get better.

Coping with bowel side effects

Tell your doctor, radiographer or nurse about any bowel side effects you have. They can give you advice to help. 

Diarrhoea is the most common side effect. It usually starts during, or after 2 weeks of radiotherapy. If you have diarrhoea, your team may give you tablets to help reduce it.

If you have any soiling or incontinence, tell your team. The will give you advice about coping with this, and looking after your skin.

Your team may advise you to make changes to your diet during radiotherapy. This will help prevent or improve bowel side effects. Follow their advice carefully, and tell them if your side effects get worse.

There are things you can do that may help with bowel side effects. We have more information about coping with bowel problems.

Effects on the vagina

If your treatment involves areas of the vagina, it can cause changes during and after treatment. Changes may include:

  • skin reactions in the vagina
  • vaginal dryness
  • narrowing of the vagina.

These changes can be uncomfortable, and may make having sex painful. They may also make it difficult if you need to have internal examinations in the future.

Your doctor, radiographer or nurse may give you vaginal dilators to help stop the vagina from narrowing. Dilators are tampon-shaped, plastic rods of different sizes. You use these regularly with a lubricant after your radiotherapy has finished. Using a vibrator, lubricated fingers or having regular penetrative sex may also help prevent vaginal narrowing.

Your nurse or radiographer will explain if dilators may be helpful, and how to use them.

Coping with vaginal dryness

A personal lubricant or moisturiser may help with dryness. This is a gel, liquid or cream that you use inside the vagina. Your doctor can prescribe one, or you can buy it from a pharmacy, other shop or online.

We have more information about coping with vaginal dryness

Menopausal symptoms

If you have not been through the menopause, pelvic radiotherapy will usually cause an early menopause. This is because this treatment stops the ovaries working. You will not be able to get pregnant anymore, and your periods will eventually stop.

For a time, you may get menopausal symptoms such as:

  • hot flushes and sweats
  • vaginal dryness
  • a lower interest in sex
  • sleep problems
  • mood swings and lower confidence.

Sometimes, you can have surgery to move the ovaries away from the treatment area before pelvic radiotherapy. This is called ovarian transposition. It may protect the ovaries and make the menopause less likely. Your doctor can give you more information about this surgery.

Coping with menopausal symptoms

Having an early menopause can be difficult to cope with, and sometimes distressing. But there are things that can help. Ask your doctor or nurse for support, and advice about treatments and managing menopausal symptoms.

We have more information about menopausal symptoms and cancer treatment.

Erection problems

Radiotherapy to the pelvic area can cause problems getting or keeping an erection. This is called erectile dysfunction or ED. You may find your erections are not as strong as they were before the treatment. You may get an erection, but then lose it. Or you may be unable to get an erection at all. Your radiotherapy team can explain what is likely to happen.

Coping with erection problems

Although you may feel embarrassed, talk to your doctor if you are having problems. There are treatments for ED that may help. We have more in our information about side effects and sexual well-being.

Changes in ejaculation

You may have a sharp pain when you ejaculate. This is because radiotherapy can irritate the tube that runs through the penis from the bladder (the urethra). The pain should get better a few weeks after treatment finishes.

After treatment, pelvic radiotherapy reduces the amount of semen you produce. This means when you ejaculate, you may only notice a small amount of fluid. Some men do not produce any semen at all. This is called a dry ejaculation. But you will still be able to orgasm (climax). You may find the sensation of an orgasm feels different from before.

Coping with changes in ejaculation

Often it can help to know what to expect. But if these changes affect your relationships or how you feel about having sex, it may help to talk to a sex therapist. We have more information about cancer and sexual well-being.