What do systematic reviews say?

Intervention not reported

The intervention showed no clear difference in overall adverse effects Duration of trials: 6 to 16 weeks (moderate certainty).

• Addition of anti‐leukotriene agents to inhaled corticosteroids for adults and adolescents with persistent asthma 2017 · Cochrane Headline outcomes only
  RR 1.06 [0.92, 1.22]
  3 studies · 1024 participants
  Moderate