Answer
It is licensed for a dry, unproductive cough. A cough producing substantial phlegm should be assessed rather than routinely suppressed.
Sources for this answer
- Benylin Dry Coughs 7.5mg / 5ml Syrup — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.