The invention relates to a method for increasing the particle size of crystalline active micro-particles comprising the following steps: (a) a first suspension consisting of crystalline active micro-particles with a first d50value of 0.5-5 �m, solvent for the active agent and anti-solvent for the active agent is provided, wherein the solubility of the active agent in the solvent/anti-solvent mixture of the first suspension is 0.001-0.5% by weight (b) the first suspension is stirred (c) the d50 value of the active micro-particles contained in the first suspension is determined at least once, wherein a second d50 value is obtained (d) the first suspension is stirred further (e) the first suspension is filtered off, wherein a filter cake is produced, which is washed with anti-solvent for the active agent, wherein a differential pressure of = 500 mbar is present between the top and bottom of the filter cake during the filtering-off process and the filter cake is dehumidified to not below 80% by weight of the anti-solvent, relative to the total mass of the filter cake, the filter cake obtained then being suspended in anti-solvent, wherein a second suspension is obtained and the d50 value of the active micro-particles of the second suspension is determined, wherein a third d50 value is obtained, wherein the total stirring time of the first suspension is selected so as to be between 1 and 72 hours, depending on the second d50 value, and/or by adding solvent and/or anti-solvent, the solubility of the active agent in the solvent/anti-solvent mixture of the first suspension is altered so as to be between 0.001 and 0.5% by weight such that the third d50 value is at least 0.03 �m greater than the first d50 value and (f) the active micro-particles of the second suspension are then dried. Moreover, crystalline fluticasone propionate particles are provided, the mean particle size being d50 = 1-1.5 �m, the span being = 1.35 and the amorphous fraction relative to the t
