A protective cap for a dispenser for discharging pharmaceutical and/or cosmetic liquids, wherein the dispenser has a liquid reservoir and an outlet opening through which the liquid can be dispensed into a surrounding atmosphere, and wherein the protective cap has at least one ventilation opening to allow communication between an interior and external surroundings. An irreversibly removable sealing element which covers the at least one ventilation opening is arranged on the protective cap, which sealing element closes the at least one ventilation opening in an airtight and germproof manner before a first use.