Bromhexine, the active substance in this medicine, belongs to so-called mucolytics that act by decreasing the viscosity of mucous secretions, fluidizing them and facilitating their elimination. This medicine is indicated to reduce the viscosity of snot and phlegm, facilitating its expulsion, in colds and flus. You should see a doctor if it gets worse or if it does not improve after 5 days of treatment.