An atomizer for a fluid, in particular, a fluid for medical aerosol therapy. In order to allow simplified operation and improved safety in use, the atomizer has a counter device for counting the number of operations of the atomizer and the number of containers inserted. The atomizer is locked against further operation and/or against removal of the current container or insertion of a new container, if a certain number of operations of the atomizer and/or a certain number of containers inserted has/have been reached or exceeded.