Hello! The trauma of going through post radiation effects is worst than the malignancy itself.Usually the symptoms of post radiation starts by 15days of therapy and last for 3-6months. Some of them last much longer. Foods taste excessively salty which may reduce the motivation for adequate oral intake. In response to their altered taste sensation, patients tend to compensate by increasing their intake of sugar which causes increased risk of dental caries. However, altered taste sensorium is a transient phenomenon since the taste buds recover in two to four months post therapy. Solution: Commercial mouth rinses should be avoided. The alcohol and phenols contained in these preparations may further dehydrate the mucosa causing further pain. Chlorhexidine should be continued during radiation therapy and may be diluted for tolerance.Currently accepted elixirs include Benadryl, antacids, sucralfate, corticosteroids, and viscous lidocaine. Dry mouth: treatment is generally utilizing artificial saliva, carrying water bottles for periodic mouth moistening. Salivary substitutes are available. Initiation of meticulous oral hygiene regimens, chlorhexidine rinses, and regular dental hygiene therapy sessions are required. Try giving semi solids and cold liquids to build his nutrition. Protein supplement powders are available which is mixed with milk and consumed. Even if he is unable to ear solid food make sure you give him a balanced diet. Improved nutritional status helps in faster healing. I hope you found my response to be helpful and informative. If you have any additional concerns I would be happy to address them. Regards Dr Divya