Solid or liquid medicinal products (including nose spay) required for travel are authorised in the cabin without medical prescription (which is not mandatory). They must nonetheless be shown at the security check points for additional arbitrary inspection at Luxembourg airport upon departure.
If during such an inspection, a liquid medicinal product that exceeds 100 ml does not comply with the regulation in force, it will be refused. In such a case, a prescription could facilitate the final decision of the authorities.