The diuretic effect of the combined furosemide and aminophylline/theophylline among pediatric patients remains unclear. The primary aim of this systematic review was to examine the clinical diuretic effects (urine output and fluid balance) of co-administration of furosemide and aminophylline/theophylline as compared to furosemide alone in pediatric population. Ovid MEDLINE, CENTRAL, and EMBASE were searched from its inception until March 2022 for observational studies and randomized controlled trials (RCTs) comparing the administration of furosemide versus furosemide and aminophylline/theophylline in pediatric population. Case reports, case series, commentaries, letters to editors, systematic reviews, and meta-analyses were excluded. Five articles with a total sample population of 187 patients were included in this systematic review. As compared to the furosemide alone, our pooled data demonstrated that co-administration of furosemide and aminophylline/theophylline was associated with higher urine output (mean difference: 2.91 [90% CI 1.54 to 4.27], p