Answer
Discard it four weeks after opening, even if some solution remains.
Sources for this answer
- Gentisone HC Ear Drops/ Gentamicin 0.3% w/v and Hydrocortisone acetate 1% w/v Ear Drops — 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.