Randomized controlled trial in 80 children with mild to persistent moderate asthma, who were randomized to receive montelukast 5mg + loratadine 5mg vs. montelukast 5mg + placebo for loratadine to evaluate the efficacy in terms of improvement of symptoms. Secondary outcome was the days off without the use of rescue medication; reduction of levels of cysteinyl leukotrienes (Cys-LTS), nitric oxide (FeNO), intracellular adhesion molecule type 1 (ICAM-1) and interleukin 8 (IL-8) in condensed exhaled air; the improvement of day and night symptoms; the reduction in the frequency of night awakenings; the improvement in the quality of life; the percentage of related adverse events; the need to use systemic steroids; the number of visits to the emergency department secondary to the presence of an asthma attack; the number of hospitalizations secondary to asthma attacks; and the improvement in the percentage of FEV1 in relation to the predicted.