Answer
Do not combine products without checking active ingredients, as this may duplicate guaifenesin or other components.
Sources for this answer
- Covonia Chesty Cough Sugar Free Syrup — Current selected SmPCemc · Summary of Product Characteristics
- Robitussin Chesty Cough Medicine — 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.