Side-effects from radiotherapy to the abdomen (tummy) and pelvis

Woman holding her pelvic area

Diarrhoea or constipation

Diarrhoea is passing watery bowel motions (poos) more than 3 times a day. It is a fairly common side-effect of radiation to this area. You may also have bleeding or a mucous discharge from your back passage.

Constipation means not having a bowel motion often enough. This is common with radiotherapy to the tummy and pelvic area. You may also have stomach cramps and wind. 

Read more about coping with constipation and diarrhoea.

Bladder problems

Sometimes radiotherapy to your pelvis can cause difficulty with passing urine. This can happen with both internal and external radiotherapy. Your bladder may become inflamed (cystitis) after a number of treatment sessions. This may cause pain, discomfort or a burning sensation while passing urine. You may also feel the urge to pass urine frequently, both during the day and at night. Sometimes you may find that you can only pass very small amounts of urine or none at all. Occasionally, blood may appear in your urine.

If you notice any of these changes, tell your doctor, radiation therapist or nurse straight away, especially if you cannot pass urine.

Irritation to the ‘back passage’

Radiotherapy can cause irritation or itchiness to your rectum or ‘back passage’ (proctitis). This is a common side-effect if the area being treated is in your lower pelvis, such as for prostate or bladder cancer. If you have haemorrhoids (piles), radiotherapy may irritate them.

Loss of appetite and weight loss

Radiotherapy to your abdomen and pelvis can cause nausea and loss of appetite. This in turn may lead to weight loss. Some people feel sick at the start of a course of treatment, but find that nausea disappears within a day or two. Tell your radiation therapist or your doctor if you suffer from nausea, as medication can be given to control it. If eating becomes a problem for you, your dietitian or doctor can advise you. Read more about coping with nausea and eating problems

Sexual side-effects

For both men and women, radiotherapy to your pelvic area can cause sexual problems. Problems can be physical, but treatment can also affect your desire for sex. It’s usually safe to have sex during and after radiotherapy treatment, unless your doctor tells you not to. Women having pelvic brachytherapy won’t be able to have sex while the implant is in place. It’s important to use contraception during and after radiotherapy. Read more about coping with sexual side-effects 

Fertility problems

If your ovaries or testicles are in the treatment area, your fertility may be affected by radiotherapy. This may be a temporary or permanent change. 

Female fertility

Radiation to the pelvis can affect a woman’s ovaries. Some or all of the eggs stored in the ovaries may be destroyed and she may stop producing female sex hormones, which can lead to early menopause. With lower doses of radiation the ovaries may heal. But changes to fertility are more often permanent.

It is sometimes possible to do a small surgery to move the ovaries away from the treatment area. This is called ovarian transposition. Or you may be able to freeze eggs before treatment starts. 

Male fertility

Sperm can be damaged or their number reduced if your testicles are in the area being treated by radiation. For example, treatment for prostate or bladder cancer. This can lead to temporary or permanent infertility. Talk to your doctor and your partner if avoiding infertility is important for you.  You may be able to freeze eggs before treatment starts. 



It’s important to use contraception during radiotherapy treatment and for a time afterwards. Even if your treatment is likely to cause infertility, you may still be fertile for a while. Radiation can harm a developing baby, so it’s very important to avoid you or your partner becoming pregnant. Talk with your doctor about contraception.

For more information

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