Trigger

A PTSD Trigger, also known as triggering content, is material that affects someone who has gone through trauma in a way that sets off Post-Traumatic Stress Disorder. Other types of triggers exist: I Need a Freaking Drink is when something triggers someone to need alcohol (or another substance). A negative behavior trigger is something that triggers an addictive response as opposed to trauma. Seizure triggers are flashing lights or other patterns that affect people with photosensitive seizures, and suicide triggering is the invoking of suicidal or hopeless feelings in a depressed person. The Berserk Button is triggering of anger or irrational rage.

Information regarding triggering or specifically relevant quotes should be placed on the Useful Notes page, which has a more in-depth description of triggers and the meta concept for those interested. This page is for the discussion of In-Universe triggering only.

Do not put trigger warnings on any All The Tropes pages other than Fan Fic Recommendations. Works that have full pages should already indicate the existence of triggering content in the description or trope list in a natural way, and a trope's description should be a good indication of whether or not there will be any significant triggering content in its examples.

Compare the Ban on Politics (an attempt at handling a near-universal Berserk Button), the Nuclear Weapons Taboo, Trigger Phrase, and Too Soon. Not to be confused with Squick which may be unsettling, but is not a psychological trigger.

Anime and Manga

 * In Clannad, Kotomi sees a bus crash and hearing that Ryou might have been on the bus caused her to have a Freak-Out. Observe.

Film

 * In the Alfred Hitchcock movie Spellbound, an amnesia victim becomes uncomfortable every time he sees a pattern of wavy dark lines against a white background, because it reminds him.
 * The original version of The Manchurian Candidate. Actually one of the first films to explore triggering in depth, before the term was even generally used to describe it. While there's plenty of Critical Research Failure and such to go around and using triggers to create an assassin is likely impossible in Real Life (thankfully), and while it is definitely Played for Drama, the idea of using emotional triggers to manipulate people into doing things they would not otherwise do or act against their own self-interest is actually Truth in Television.
 * In The Muppets (2011), they find Animal in a therapy session to control his aggressive impulses. Turns out "drums" is a trigger word for him, to no one's surprise. It's also one for Jack Black.

Literature

 * The protagonist of Use of Weapons refuses to sit in chairs. It almost feels as if this Played for Laughs at first, until the references to a white chair and "the Chairmaker" pile up more and more often. It isn't until the end of the book that you learn he has very good reasons for it.

Live Action TV

 * On Cheers when Woody's old girlfriend shows up he constantly goes out eating with her. He reveals that he used to be obese back in Indiana but since he moved to Boston he's thin. The other guys realize his old girlfriend is his eating trigger, but don't know how to break it to him.
 * True Blood:
 * After Lafayette gets out of, Detective Andy approaches him in the kitchen at Merlotte's, where Lafayette works. The next scene is basically him threatening to put Layfayette back in exactly the situation he just escaped from. Terry, a veteran with PTSD who probably recognized the signs since Lafayette had fallen down, terrified, calls the officer in question on this in a sort of one-on-one Shaming the Mob.
 * Terry also appears to have gotten one just before we come on-screen. Which makes sense, since he's an Iraq war vet who had just seen
 * Josh from The West Wing has a flashback trigger in Christmas music, because his delayed-reaction PTSD erupted right around Christmastime, and he mentally associated the constant caroling of the band in the White House lobby with the sirens from the assassination attempt during which he was near-fatally shot.
 * The Inspector Lynley Mysteries: Barbara Havers, back on the job after being in the previous episode, shows obvious signs of PTSD throughout the episode; she is nervy and jumpy even more than her usual. Lynley is concerned, but doesn't want to interfere. When she is, however, Barbara completely flies off the handle and attacks , using him for a punching bag until Lynley gets there, pulls her off and talks her down with a Cooldown Hug. It must be emphasized that he could only manage this because of Barbara's implicit and unconditional trust in him; anyone else trying the same thing would have also been used as a punching bag, and in fact Barbara obviously nails Lynley a time or two before he can get through to her and she recognizes him.

Web Comics

 * In Sinfest, Slick sees the pit leading to Hell, and remembers when he was in Hell.
 * In Goblins, Kin is triggered by being trapped under a tree, since she used to be raped nightly be Dellyn Goblinslayer, who was part-tree.

Western Animation
"Edward: You and Trevor have a lot in common, you know. Douglas: And what might that be? Edward: Scrap. Douglas: Don't use that word! You're making my wheels wobble!"
 * Played for laughs (inevitably enough) in Family Guy, where Peter's impersonation of Ralph from The Honeymooners triggers Lois' brother's memories of walking in on their mother's affair with Jackie Gleason (an event which put him into an insane asylum and turned him into a serial killer).
 * From Thomas the Tank Engine:

Web Original

 * Rise, an Original Character tournament game, has one of these for almost every character.
 * Flippy from Happy Tree Friends takes this trope to the extreme; anything can (and will) trigger his PTSD.