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6.3 Radiation Reactions

​Updated: May 2003

Radiation therapy inevitably causes damage to the normal tissues in the path of the beam(s). This damage is referred to as the radiation reaction. When it occurs during and immediately after treatment it is called an early or acute reaction or acute. When it occurs more than 3 months after treatment it is referred to as the late reaction or damage.

Acute reactions

The acute reaction from treating oral cavity, oropharyngeal, nasopharyngeal, hypopharyngeal or laryngeal tumours will be similar and individual symptoms will largely depend on the tissues that have been treated.

Functional changes due to inflammation caused by the radiation will depend on the tissue involved, for example most patients will develop transient hoarseness if their larynx is irradiated and pain or difficulty eating if the mouth is treated. During a five or six week course of treatment, few symptoms will develop in the first 2 weeks except that the saliva may become thicker and more difficult to clear. Then the treated tissues will start to become inflamed and the patient will develop a painful mucositis. The reaction will usually reach its peak in the last 2 weeks of treatment and persist largely unchanged for about 2 weeks after the treatment has finished. Then it usually heals quite quickly and most symptoms should have resolved within four weeks of the completion of treatment. When chemotherapy has been combined with radiation or a twice daily radiation treatment schedule has been used, the reaction may be more severe and take longer to heal.


  1. Reassurance
  2. Maintenance of fluid intake with oral fluids or intravenous infusion if necessary.
  3. Maintenance of adequate nutirition. Dietary supplements are often required. A feeding gastrostomy may be required and patients who are to be treated with regimens that usually produce severe mucositis will be offered prophylactic insertion of a feeding gastrostomy.
  4. Most patients require analgesics such as acetaminophen and codeine, occasionally some require stronger narcotics. Effective analgesia is often essential to maintain adequate fluid and calorie intake and patients should try to time their meals so that they have taken some analgesic about half an hour before eating. Mucaine or xylocaine viscous taken shortly before meals may assist swallowing.
  5. Some patients will develop oral candidiasis which should be treated with Nystatin oral suspension. Thrush can be difficult to differentiate from the fibrinous mucositis caused by the treatment, but typical colonies are usually seen in unirradiated tissue. Occasionally patients will also require treatment with a broad spectrum antibiotic. Although some trials have suggested that prophylactic administration of antibiotics and antifungals reduces the severity of mucositis, other trials have failed to show an effect and the situation at this stage is unclear.

Skin Reaction

Erythema progressing to dry, and sometimes moist, desquamation is usual. This starts to heal within 2 weeks of completing treatment. The treated area is often pigmented for some months and evenually returns to normal with or without some depigmentation and telangiectasia. When hair bearing skin is in the entry or exit beam of one or more radiation fields, it is likely that there will be epilation. If the dose exceeds the tolerance of the hair follicles, this epilation will be permanent, if not, the hair will regrow starting approximately 3 months after the completion of treatment.


  1. Avoid irritation from rubbing, clothing and excessive heat or cold
  2. Leave open to the air.
  3. Where necessary, apply steroid creams without antibiotics
  4. Where possible, allow to dry and crust and allow the crusts to fall off spontaneously
  5. If infection develops, treat with appropriate systemic antibiotics
  6. If there is significant moist desquamation, daily topical treatment with 1% Flamazine often speeds the healing and prevents infection.

Late radiation damage

This is mainly due to damage to the microvasculature which is present in subclinical levels in nearly all patients but only progresses to radiation necrosis in bone or soft tissue in approximately 5% of cases. It is more common in patients with conditions that also damage small blood vessels such as diabetes. It may be caused or exacerbated by any form of trauma, e.g., dental extraction, biopsy, injury or infection (see dental section below). Treat conservatively, wherever possible by minimising aggravating factors such as a rough tooth or an ill fitting denture. Where possible, avoid biopsy which may cause further damage. Antibiotics may be helpful in bone necrosis. Some patients may be referred for hyperbaric oxygen therapy which appears to increase the blood supply to irradiated tissue and promote healing of necrotic areas.

SOURCE: 6.3 Radiation Reactions ( )
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