What are the negative side effects of having Radiotherapy?

Cancer treatments have to be strong and powerful to have the best chance of killing off cancerous cells and improving the chances of making a full recovery.

However, the downside to this is while they are designed to have as much impact as possible, this can also mean patients have to endure some unpleasant side effects.

When it comes to radiotherapy, the repercussions of the treatment varies from person to person, depending on the type of cancer, its stage and grade, and the health, age and weight of the patient.

Before learning what the most common side effects may be, it is important to fully understand what radiotherapy is and how it is used to treat cancer.

Radiotherapy explained

Radiotherapy works by using radiation rays to destroy cancer cells in the targeted area.

It is often used in the early stages of cancer to cure it completely, or in conjunction with chemotherapy to make the combination of treatments more effective. Some patients may also receive radiotherapy before surgery to reduce the size of the tumour to make it easier for surgeons to remove it all.

Sometimes doctors assign a course of radiotherapy after surgery as a preventive measure to reduce the chances of the cancer returning.

However, it can also be used in the later stages of cancer if a cure is not possible. This treatment, which is known as palliative radiotherapy, helps to relieve the symptoms of cancer, and slows down the spread of the cancerous cells.

Although the radiation rays are administered by a machine to carefully target the affected area, they can frequently damage healthy cells too. This is what leads to patients suffering from adverse side effects.

The main side effects of radiotherapy

As previously mentioned, the severity and types of side effects experienced after radiotherapy is dependent on different factors. However, the most common ones are:

  • Skin reactions
  • Fatigue
  • Hair loss
  • Nausea and vomiting 
  • Problems eating and drinking
  • Diarrhoea
  • Changes in bleeding

Skin reaction

As a result of the external beams, skin reactions following radiotherapy are common. Patients often find their skin becomes red, sore, itchy or darker around ten days after treatment.

The affected area may even blister or leak fluid, but it should improve after a few weeks.

To soothe sore skin, it is wise to avoid certain products, and simply wash it gently with soap and water. Wearing loose-fitting clothing from natural fibres, protecting the area from the sunshine, avoiding using heating or cooling pads and pat drying is also advisable.


Radiotherapy fatigue typically worsens throughout the course of treatment. Usual daily activities may begin to feel too exhausting, which might continue for a few weeks or months after treatment has ended.

Those who have a combination of chemotherapy and radiotherapy could also experience more fatigue.

To combat this tiredness, give yourself a break and make sure you get plenty of rest. Make sure you get help with daily tasks, eat healthily to keep your body fueled, and do gentle exercise, such as short walks, to boost energy.

Hair loss

Hair loss from radiotherapy is typically only from the area being treated. Hair tends to fall out two to three weeks after the start of treatment and should start to grow back a little while after it has finished.

Those with a high dosage of radiotherapy may experience permanent hair loss in the targeted area.

If the hair loss is on your head due to a brain tumour, you may want to wear a wig or a headscarf if you are self-conscious about it.

Nausea and vomiting

Those who are having radiotherapy near or on their stomach or brain are more likely to experience nausea and vomiting.

Patients should tell their doctor if they feel sick, as they can be prescribed anti-sickness drugs. It is also helpful to sip drinks slowly and ask loved ones to help you prepare meals.

Problems eating and drinking

It is usual for people to experience problems eating and drinking after radiotherapy, as they may have a sore mouth, suffer from a loss of appetite or find it hard to swallow.

Radiotherapy can cause the inside of the mouth to feel sore, become dry, or have mouth ulcers. It may also be harder to swallow food if you have had treatment to the head, neck, oesophagus or chest, and a diet of soft or liquid foods may help shortly after treatment.

Some people also lose their appetite due to nausea, fatigue and a reduced sense of taste. Eating small meals throughout the day could prevent weight loss, so patients can remain fit and well while they are undergoing treatment.


Those who have had radiotherapy on their pelvic area or their stomach are likely to have diarrhoea after their treatment.

This can be very uncomfortable, so patients should ask their doctors for medicine to ease their symptoms.

Changes in bleeding

If you find you have nosebleeds, bleeding gums, blood in your urine or stools, heavy periods or red spots on the skin, this could be a sign that the radiotherapy has reduced the number of blood cells produced by your bone marrow.

Though this will start to normalise after the end of treatment, patients who have symptoms of an infection should contact their doctor straightaway.

Other side effects

While these are the most common side effects, there are others that can occur.

For instance, those whose brain tumour is being targeted might suffer from memory or concentration problems, blurry vision or headaches.

Patients whose pelvic or rectum is having radiotherapy could face sexual, urinary and bladder problems and, potentially, long-term fertility difficulties.

Despite the unpleasant symptoms, this form of cancer treatment is one of the most reliable and widely available.

That is why those who have been given a diagnosis should not hesitate contacting a radiotherapy centre to book in their treatment as soon as they can, as eradicating the cancer and increasing life expectancy is, for most people, worth the negative side effects.