Why should I use Fungisan? Fungisan is a unique formula to aid in the control of skin infections. It contains benzalkonium chloride (0.15%) a disinfecting agent; and allantoin to aid in promoting healthy skin. Fungisan is an-easy-to-use spray formula. All you do is spray a small amount on the affected area and repeat application daily until hair begins to grow back. Leave the treated area uncovered. Fungisan will not stain. Rinse the treated area or areas with clear water before each application (Fungisan's efficiency is neutralized by soap or detergent residues).