Montelukast + Levocetirizine Hydrochloride (L-HIST) is contraindicated in patients with known hypersensitivity to Montelukast or Levocetirizine, patients with severe (creatinine clearance less than 10 mL/min) or hepatic impairment, in children 6-11 years of age with renal impairment, and women who are pregnant or breastfeeding.