Mass Psychogenic Illness (MPI) refers to a phenomenon where a group of people experiences similar physical symptoms without a clear medical cause. This often occurs in close-knit communities or groups, where stress, anxiety, or environmental factors can trigger these symptoms. Common examples include headaches, nausea, or fainting, which can spread rapidly among individuals. The condition is thought to be linked to psychological factors rather than biological ones. It can be influenced by social dynamics, such as groupthink or shared beliefs. Notable historical instances of MPI include the Toxic Lady incident in 1994 and the 1980s outbreaks in schools, highlighting its impact on communities.