Tests in animals have revealed potential problems related to using leukotriene modifiers during pregnancy, and the effect on a human fetus is not clear. Before using leukotriene modifiers, patients should tell their healthcare provider if they are pregnant or plan on becoming pregnant. Women who discover that they are pregnant while taking the drug should also notify their physician immediately. 

Nursing mothers should be cautious about using leukotriene modifiers, as some types have been found to pass into breast milk. The potential effects on an infant are not known, and mothers taking leukotriene modifiers are encouraged to discuss breastfeeding risks and benefits with their physicians.

Children 5 years of age and older can be prescribed zafirlukast for the continuous treatment of asthma. Montelukast sodium is approved for the management of asthma in children aged 12 months and older and the treatment of exercise-induced asthma in children aged 15 years and older. When used to treat the symptoms of allergic rhinitis (hay fever), montelukast sodium is prescribed to treat seasonal allergic rhinitis in children ages 2 years and older, and perennial (year-round) allergic rhinitis in children aged 6 months and older.

Parents are encouraged to discuss the risks and benefits of leukotriene modifiers use with their child's physician.

Leukotriene modifiers may produce greater side effects in adults over the age of 60. Lower doses of the drug may be required for adults in this age group.