Whether or not you experience side effects during or after radiotherapy depends on many factors. These include the strength of the radiation dose, the part of the body being treated, and what organs are within the irradiated area. What’s more, radiation affects different people in different ways.
In most cases the side effects are only temporary. They may appear a few days after treatment and some can last for a few weeks.
Tiredness is the most common general side effect of radiotherapy. It can arise after only a few treatment sessions. Its exact cause is not known. It is suspected that it may come from the body breaking down the cancer cells that die during the therapy.
The side effects that occur directly within the scope of the applied radiation include skin irritations. Not unlike sunburn, the skin can become sensitive and slightly reddened. After three or four weeks the skin may become dry and start to peel, which is sometimes associated with itching. After that it often gets darker because of increased pigment formation.
Radiotherapy used near the digestive tract can cause nausea, vomiting or diarrhea.
Many of these side effects can be effectively treated, for example by using medication.
Whenever possible, the medical staff will attempt to protect your genitals (testicles or ovaries) from the radiation so it doesn’t affect your fertility. If radiotherapy needs to be used in your pelvic region, the doctor will inform you of possible harmful effects and give you advice on how they can be kept to a minimum.