A system and a method for treating lice and nits on a head of a patient. The system includes a cap for defining an airtight space around the head and a container for storing a mixture of gases for treating lice, a gas release mechanism for delivering the mixture of gases into the airtight space as an aerosol, and a gas distribution device having plurality of gas delivery pins. The mixture of gases causes irreversible damage to essential mechanisms of the lice. According to another embodiment of the present invention the system includes a cap for defining an airtight space around the head and an active agent container. The active agent of the type of acetic acid, stored in a liquid state, and vaporized during use, then circulated toward the cap.
