Dengue Hemorrhagic Fever is a mosquito-borne viral disease endemic in the Philippines which caused multiple epidemics. Most points to the activation of the complement system secondary to humoral respond leading to cytokine release causing systemic inflammation. Melatonin, is a hormone which has an a) anti-viral, b) immunomodulator, c) antioxidant, d) modulatory effect on hematopoiesis and e) anti-inflammatory action. This is a randomized control trial to determine the effectiveness of adjunctive melatonin therapy among patients diagnosed with Dengue fever with Warning Signs. This would include children aged 5 to 18 years old with no signs of hemmorhagic shock. They would be randomly assigned into 2 groups. Baseline Complete blood count with platelet (CBCPC) will be collected. Daily CBCPC will be collected and would be statistically analyze after the study.