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.

Asthma is a disease with increasing prevalence worldwide that produces significant deterioration of the quality of life in children and development of important complications and economic, social impact. Considering the concept of a common airway (coexistence of asthma and rhinitis), joint management initiatives with anti-asthmatics and anti-histamines have been published. The primary objective of this clinical trial is to evaluate the efficacy and safety of the use of montelukast + loratadine in children with asthma on the improvement of symptoms and secondarily to evaluate the impact on a) the days off without the use of rescue medication; b) 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; c) the improvement of day and night symptoms; d) the reduction in the frequency of night awakenings; e) the improvement in the quality of life; f) the percentage of related adverse events; g) the need to use systemic steroids; h) the number of visits to the emergency department secondary to the presence of an asthma attack; i) the number of hospitalizations secondary to asthma attacks; and j) the improvement in the percentage of FEV1 in relation to the predicted. We included 80 children from 6 to 12 years old, any sex, with mild to moderate persistent asthma, after signing an informed consent letter by parents or guardians or signing the child's consent (> 8 years). Children with chronic diseases associated with the disease of interest were excluded (heart disease, nephropathy, liver disease of any kind); with any other lung disease other than asthma; with a history of hypersensitivity to montelukast or loratadine or with a history of concomitant use of medications that interact significantly with montelukast or loratadine

Inclusion Criteria:

• Age from 6 to 12 years old
• Any sex
• Persistent mild to moderate asthma
• Signature of informed consent letter by parents or guardians
• Letter of assent of the minor for children over 9 years of age

Exclusion Criteria:

• Chronic pathologies associated with the disease of interest (heart disease, nephropathy, liver disease of any kind)
• Any other lung disease other than asthma
• History of hypersensitivity to montelukast or loratadine
• Concomitant use of medications that interact significantly with montelukast or loratadine

Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor) Children allocated on different arms will receive montelukast + loratadine vs. montelukast + placebo. Both product are identical in appearence and flavor