Side effects of radiation therapy

Radiation therapy side effects vary depending on the area treated, the number of sessions, and whether it is combined with chemotherapy. Side effects often get worse 2–3 weeks after treatment ends and then start to improve. Some side effects may last longer, be ongoing or appear several months or years later. The most common short-term and long-term side effects are listed below.

Learn more about managing side effects after head and neck cancer treatment.

During or immediately after treatment

Short-term side effects can include fatigue, mouth sores, taste changes, loss of appetite, dry mouth and thick saliva, swallowing difficulties, skin redness, burning and pain in the area treated, breathing difficulties and weight loss.

Ongoing or permanent

Longer-term side effects may include dry mouth, thick saliva, difficulties with swallowing and speech, changes in taste, fatigue, muscle stiffness, neck swelling, appetite and weight loss, mouth infection (oral thrush), hoarseness, dental problems such as tooth decay, difficulty opening the mouth, and hair loss.

Aspiration

Some people develop a temporary or ongoing problem where fluid or food enters the windpipe while swallowing. This is called aspiration and it can cause coughing, lung infections such as pneumonia and, sometimes, difficulty breathing.

Thyroid damage

If the treatment damages the thyroid, it can cause an underactive thyroid (hypothyroidism). This can be managed with thyroid hormone replacement tablets.

Osteoradionecrosis of the jaw

Radiation therapy can damage blood vessels, reducing the blood supply to the area treated. Occasionally, the bone starts to die, leading to pain, infection and fractures. This is known as osteoradionecrosis or ORN. About 5–7% of people who have radiation therapy to the head and neck develop ORN of the jaw. It can occur months or years later, most commonly after having dental work such as the removal of teeth, when the bone is unable to heal itself. This is why you will usually see a dentist before your cancer treatment, so any dental issues can be treated before there is a risk of ORN.

It is very important to tell your dentist that you have had radiation therapy before beginning any dental work. Treatment for ORN may include antibiotics, other medicines or surgery. To help the bone heal, you may also have hyperbaric oxygen treatment (breathing in concentrated oxygen in a pressurised chamber).

Video: What is radiation therapy?

Watch this short video to learn more about radiation therapy (also known as radiotherapy).