Hypersensitivity reactions including anaphylaxis (over sensitivity reactions including severe allergic reaction). Montelukast: Churg-Strauss syndrome (inflammation of medium & small blood vessels); drug interaction w/ medicines that inhibit some liver enzymes (eg, phenobarb, phenytoin & rifampicin); hyperkinesia (hyperactivity); increase in hepatic (liver) enzymes ALAT & ASAT; hallucinations (seeing, hearing or feeling); irritability, anxiety (generalized fear), agitation, depression, suicidal thought & behavior; dyspepsia, abdominal pain, rash, dizziness, headache, fatigue, fever, trauma, cough, nasal congestion. Levocetirizine: Impairment of kidney function (renal impairment); sedation; iridocyclitis; effects on the CNS when concomitantly administered w/ alcohol; urinary retention; somnolence, fatigue, nasopharyngitis, dry mouth, & pharyngitis.