Answer
Selected products contain aspartame, a source of phenylalanine. People with phenylketonuria should check the exact product leaflet with a pharmacist or prescriber.
Sources for this answer
- Montelukast 5 mg Chewable Tablets — Current selected SmPCemc · Summary of Product Characteristics
- Singulair Paediatric 4 mg tablets — Current selected SmPCemc · Summary of Product Characteristics
- Singulair Paediatric 5 mg Chewable Tablets — Current selected SmPC