Adding trigger warnings to a book blurb is something that most authors have to take into account. When dealing with things like BDSM, War, domestic abuse, suicide, rape and so much more, authors need to understand that their fictional story will have an impact with their reader. Warning the readers that these subject matters will be mentioned or included may spoil a major plot arc in your story, but isn’t it better to do that than for one reader to have an anxiety attack or suffer PTSD symptoms, because you didn’t warn them?
People who have personal experience of these events often don’t talk about it in public. So whether you know them or not, there’s no way to tell every victim/survivor in the world that there are trigger events in the book, if you don’t add a trigger warning in the book description.
Make it a few lines under the blurb, if you want, for those who don’t want to read the warnings. Make it in asterisks or put TRIGGER WARNINGS in all caps, so that they can see what they’re about to read. Either way, it’s your responsibility as an author to warn your readers that they may stumble into emotional, physical or heavy events within the book that may hurt them or trigger bad memories, an anxiety attack or worse.
An author who doesn’t care that they might trigger PTSD or anxiety in a reader is an irresponsible one. Not adding a trigger warning when you know fine well that the subject matter may be harmful to a reader is awful. It’s dismissive and potentially dangerous to all potential readers that may pick up your book, without realising what effect it may have on them.