The invention relates to the use of substances that influence fungal dimorphism for reducing the adhesion of fungi to surfaces. The invention also relates to washing and/or cleaning agents, textile treating agents and cleaning agents for mouth, teeth or dentures and to the use of said substances in said agents. The inventive substances are selected from propolis extracts, plant extracts, cinnamic acid and the derivatives thereof, monoterpenes, sesquiterpenes and diterpenes and the derivatives thereof, especially fucoidine, anethol, geraniol, farnesol or farnesol acid.