Answer
Covonia Chesty Cough Mixture Mentholated has an unopened shelf life of 36 months for all listed bottle sizes: 50, 150, 180, 200 and 300 ml.
Sources for this answer
- Covonia Chesty Cough Mixture Mentholated / Covonia Mucus Cough Oral SolutionThornton & Ross Ltd · emc · SmPC §6.3 Shelf life · Version 5Document updated
Sources checked