Mysophobia refers to the intense and irrational fear of germs, dirt, or contamination. It is a type of specific phobia, which is a fear that is pervasive and interferes with daily functioning. An individual with mysophobia has an obsessive worry about contracting an illness from various sources, including bodily fluids and bacteria.

It is one of the most prevalent types of obsessive-compulsive disorder (OCD), a psychiatric diagnosis characterized by excessive thoughts (obsessions) that lead to repetitive behaviors (compulsions).

Repetitive behaviors associated with mysophobia may include excessive hand washing or bathing. Individuals with mysophobia may also feel an intense urge to avoid situations where they feel they can become contaminated, or they may go to extreme efforts to remove sources of contamination.