People: Seeing a person related to the trauma may set off a PTSD reaction. Or someone may have a physical trait that’s a reminder. For example, if someone with a beard mugged you, other bearded men may bring back memories.

Thoughts and emotions: The way you felt during a traumatic event (afraid, helpless, or stressed) could cause symptoms.

Things: Seeing an object that reminds you of the trauma can cue your PTSD symptoms.

Scents: Smells are strongly tied to memories. For instance, someone who survived a fire might become upset from the smoky smell of a barbecue.

Places: Returning to the scene of a trauma is often a trigger. Or a type of place, like a dark hallway, may be enough to bring on a reaction.

TV shows, news reports, and movies: Seeing a similar trauma often sets off symptoms. This includes scenes from a television show or movie, or a news report.

Feelings: Some sensations, such as pain, are triggers. For survivors of assault, a touch on a certain body part may lead to a flashback.

Sounds: Hearing specific noises, songs, or voices may bring back memories of the trauma. For example, hearing a car backfire may remind a veteran of gunfire.

Tastes: The taste of something, like alcohol, may remind you of a traumatic event.

Situations: You may tie scenarios with the trauma. For instance, being stuck in an elevator might remind you of feeling trapped after a car accident.

Anniversaries: It’s often hard to go through a date marked by trauma without remembering it, as is the case for many survivors of the terrorist attacks on September 11, 2001.

Words: Reading or hearing certain words could cue your PTSD.