During a PTSD episode, the person may relive the trauma that caused their PTSD through intrusive thoughts, flashbacks, visions, and nightmares. They may also experience intense anxiety and debilitating fear. The physical symptoms of a PTSD episode can include shaking, sweating, racing heart, and difficulty breathing.

A PTSD episode, often referred to as a "flare-up" or "trigger response," can manifest in several distinct ways depending on the individual. One common experience is a flashback, where the person feels as though they are physically re-living the traumatic event; this can involve sensory hallucinations like smelling smoke or hearing specific sounds. To an observer, the person might appear "spaced out" (dissociation) or may physically tremble, sweat, or experience a racing heart. Another form is hypervigilance, where the person becomes extremely agitated, scanning the room for exits or reacting with an exaggerated startle response to loud noises. Emotional "numbing" is also possible, where the individual becomes completely unresponsive or flat. In 2026, mental health experts emphasize that these episodes are often "invisible" to the public, appearing only as intense anxiety or a sudden need to leave a crowded space. It is a physiological "hijacking" of the nervous system where the brain's "alarm system" (the amygdala) overrides the logical centers.