> Public awareness that Tylenol causes liver failure which will last weeks before death might dissuade some.

I suspect it will: There's statistical evidence from how Britain migrated its cooking gas systems away from carbon-monoxide-heavy mixes [0] indicating overall suicide-rates are sensitive to convenience and involve short-term periods of vulnerability. As contrasted to "if they really want to they'll find a way no matter what." [1]

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[0] https://www.npr.org/2008/07/08/92319314/in-suicide-preventio...

[1] That said, I wouldn't be surprised if there's a bimodal distribution lurking in there, between "depressed but otherwise healthy" versus "terminal diagnosis and chronic pain." The latter-group might not be deterred by inconvenience.