Lactose intolerance is common among diarrheal children due to compromised gut health. Diarrhea can damage the intestinal lining, reducing lactase enzyme production responsible for lactose digestion. Consequently, lactose, a sugar found in dairy products, remains undigested, leading to abdominal discomfort, bloating, and increased bowel movements. Objective: To assess the clinical characteristics of Lactose intolerance (LI) as well as its relationship with demographic factors among diarrheal children below five years of age. Methods: A cross sectional study was conducted enrolling 50 diarrheal patients in equal proportion by gender. The present study was conducted over children suffering from profuse diarrhea admitted to the Pediatrics ward at LUMHS and CIVIL hospital Hyderabad, Pakistan during July 2018 to January 2019. The questionnaire-based analysis was conducted to gather information regarding dietary index and manifestation of symptoms after milk consumption. Clinical analysis was performed using lactose tolerance test, Stool pH and reducing substance respectively. The obtained results were analyzed using SPSS. Results: 20 children were found to be suffering from lactose intolerance. The clinical symptoms observed among individuals affected by LI included loose motion, weight loss, abdominal distention, and the presence of pus cells in stool indicating the signs of infection. T-test showed statistical significance (p-value ˂ 0.05) over physical attributes such as height and number of pus cells among LI patients as compared to lactose tolerant (LT) patients. The finding of pus cells in the stool simultaneous to the strong statistical correlation between relieve in symptoms with increasing age also affirmed the existence of secondary type hypo-lactasia. The study also highlighted the demographic aspects contributing to the prevalence of the condition. Conclusions: Secondary lactose intolerance was found with shortened heights of patients and increased number of pus cells in stool.