Fol­low­ing radio­ther­apy, it is highly likely you will have side effects. Side effects occur because radio­ther­apy dam­ages some of your healthy cells as well as des­troy­ing the can­cer­ous ones.

Side effects will depend on:

  • the part of your body being treated,
  • the dose of radio­ther­apy, and
  • how quickly the healthy cells are able to repair the damage.

Radio­ther­apy affects dif­fer­ent people in dif­fer­ent ways and it is dif­fi­cult to know exactly how you will react to the treatment. Some people exper­i­ence mild side effects but for oth­ers they are more severe. Some side effects begin dur­ing treat­ment. Oth­ers can appear weeks or months after­wards. Before start­ing treat­ment, dis­cuss the pos­sible side effects with your treat­ment team.

Com­mon side effects of radio­ther­apy include:

  • tired­ness,
  • nausea,
  • diarrhoea,
  • stiff joints and muscles,
  • dry mouth,
  • loss of appetite,
  • hair loss,
  • sore skin, and
  • a lack of interest in sex.

Tired­ness

You will prob­ably feel tired both dur­ing and after your radio­ther­apy treat­ment. Tired­ness is par­tic­u­larly com­mon towards the end of a course of treat­ment and can last for some time.

Tired­ness usu­ally occurs as a res­ult of the body repair­ing the dam­age to healthy cells. It can also be caused by anaemia (a short­age of red blood cells).

Anaemia can develop if too many healthy red blood cells are des­troyed dur­ing treat­ment, mean­ing less oxy­gen is car­ried around your body. Dur­ing your treat­ment, you will have reg­u­lar blood tests. If you have anaemia, you may need a blood transfusion.

Doing some gentle exer­cise may help relieve the symp­toms of tired­ness. Your doc­tor or treat­ment team can advise you about suit­able exercise.

Nausea

Some people feel sick at the start of their treat­ment. Oth­ers feel sick dur­ing it or for a short period of time after it has fin­ished. If you are affected by nausea, your doc­tor or radio­ther­ap­ist may be able to pre­scribe med­ic­a­tion to con­trol it.

Diarrhoea

Diarrhoea is a com­mon side effect of radio­ther­apy to the abdo­men (stom­ach) area. It usu­ally starts a few days after treat­ment begins and gradu­ally gets worse as treat­ment continues.

After your treat­ment has fin­ished, your diarrhoea should dis­ap­pear within a few weeks.

Tell your doc­tor if you notice any blood in your stools (fae­ces). If your symp­toms have not improved after a few weeks, tell your radio­ther­ap­ist. They may refer you to a gast­roen­ter­o­lo­gist (a spe­cial­ist in stom­ach and bowel disorders).

Stiff joints and muscles

Some­times radio­ther­apy can cause your muscles to tighten up and your joints to become stiff in the area being treated. You may exper­i­ence some uncom­fort­able swell­ing in the affected area.

Exer­cising your joints and muscles reg­u­larly can help pre­vent stiff­ness. If you have stiff joints and muscles, your doc­tor or radio­ther­ap­ist may refer you to a physio­ther­ap­ist, who can recom­mend suit­able exercises.

Loss of appetite

The com­bin­a­tion of feel­ing sick and tired dur­ing radio­ther­apy can make you lose your appet­ite. You may have dif­fi­culty swal­low­ing if you are hav­ing radio­ther­apy to your head, neck or chest.

If you have dif­fi­culty eat­ing, you may find it easier to eat sev­eral small meals through­out the day, rather than a few lar­ger meals. You can also speak to your radio­ther­ap­ist who, if neces­sary, may refer you to a dieti­tian (nutri­tional specialist).

Sore skin

After external radio­ther­apy, your skin may become red and sore in the area being treated. Your treat­ment team can give you advice about the best way of caring for your skin dur­ing treatment.

If your skin becomes sore, try not to irrit­ate it fur­ther. Avoid shav­ing and using per­fumed soap in the affected area. Pro­tect your skin from cold winds and wear a high-factor sun­screen (SPF 15 or above) to pro­tect your skin from the sun.

Hair loss

Hair loss is another com­mon side effect of radiotherapy. Many people find los­ing their hair stress­ful and dif­fi­cult to cope with. Los­ing your hair can affect your con­fid­ence and may make you feel depressed.

Talk to your fam­ily and friends about how you are feel­ing so they can sup­port you. After a few weeks of fin­ish­ing treat­ment, your hair should start to grow back.

You may con­sider get­ting a syn­thetic (man­made) wig or a wig made from human hair.

Effects on sex and fer­til­ity in women

Hav­ing radio­ther­apy may cause you to lose interest in sex, par­tic­u­larly if you have other side effects such as tired­ness or nausea or if you are anxious about your con­di­tion or treatment.

Radio­ther­apy to the vaginal area may cause your vagina to become nar­rower. Your radio­ther­ap­ist will tell you how you can treat this using a vaginal dilator, a device that is inser­ted into your vagina to help pre­vent nar­row­ing. Hav­ing sex reg­u­larly after your treat­ment can also help pre­vent your vagina narrowing.

If you exper­i­ence vaginal dry­ness or pain when hav­ing sex, you can use lub­ric­ants, or ask your doc­tor or radio­ther­ap­ist to pre­scribe appro­pri­ate medication.

Radio­ther­apy dir­ec­ted at the pel­vic area exposes the ovar­ies to radi­ation. In pre-menopausal women, this may cause early men­o­pause and infer­til­ity (the inab­il­ity to get preg­nant). This is often very upset­ting, par­tic­u­larly for younger women who want to have a fam­ily. Before your treat­ment, your radio­ther­ap­ist will dis­cuss all the options and avail­able sup­port with you.

For example, it may be pos­sible for some of your eggs to be sur­gic­ally removed, frozen and stored until you are ready to have a baby. This will not be pos­sible if you need radio­ther­apy immediately.

Radio­ther­apy to other areas of the body will not affect your ovar­ies or make you infertile.

Effects on sex and fer­til­ity in men

In men, tem­por­ary impot­ence (the inab­il­ity to get an erec­tion) and loss of interest in sex are com­mon side effects of radio­ther­apy. This is often caused by feel­ing tired after radio­ther­apy and being anxious about the treat­ment or illness.

Radio­ther­apy to the pel­vic area can cause tem­por­ary impot­ence by affect­ing the nerves in and around your penis. Most other radio­ther­apy treat­ments will not make you infer­tile or cause any prob­lems if you decide to have chil­dren in the future.

If there is a risk that you could become infer­tile, your radio­ther­ap­ist will dis­cuss this with you before your treat­ment. It may be pos­sible to store your sperm until you decide to have a baby.