The study evaluates the effect of melatonin for preventing concurrent radiochemotherapy induced oral mucositis and xerostomia and improving quality of life in head and neck cancer patients. This is a randomized, double-blind, placebo controlled trial conducted in head and neck cancer patients. Mixed-block randomization is used to divide eligible patients into two groups: melatonin 40 mg or matched placebo. The patients are required to take the studied drugs 20 mg suspensions before radiation and 20 mg capsules at night (after 21.00 pm) on the first night of radiation and continue for 7 weeks. Standard treatment is Radiation 2 Gy 5 fraction/week not more than 7 weeks with Cisplatin chemotherapy base regimen according to standard hospital protocol. Study endpoints are level of mucositis (CTCAE scale, WHO scale and MTS scores), level of xerostomia (CTCAE scale, VAS), QOL (FACT-H&N), pain (VAS 0-10) and adverse event frequency.

Inclusion Criteria:

• New diagnostic of head and neck cancer patient who need treatment with radiation involved with the oral cavity area.
• Never received radiotherapy or chemotherapy
• Karnofsky performance status > 70%
• Stopped smoking
• Able to eat and swallow medications
• Written informed consent

Exclusion Criteria:

• Melatonin allergy
• Active oral cavity inflammation scar
• Pregnancy
• Creatinine clearance < 30 ml/min
• Active periodontal disease
• Steroids or pain killer drugs used for oral cavity pain except NSAIDs for thromboembolism prevention
• Currently use benzydamine mouthwash