A method for manufacturing a parasiticidal composition comprising at least 40% of alkali metal bicarbonate and at least 1% of silica, wherein: at least 35% of the alkali metal bicarbonate of the composition is milled in the presence of silica in order to form a mixture of particles, and if necessary, the remainder of the alkali metal bicarbonate is added to the mixture of particles to form the parasiticidal composition, and wherein said parasiticidal composition has a particle size distribution such that at least 50% by weight of the particles have a diameter of less than 100 μm. A parasiticidal composition obtained by the present method and the use of the parasiticidal composition obtained by the present method in the form of a powder, a suspension or a gel.
