This WeakAura

This is a click-to-apply WeakAura that reminds you to apply poisons when they're missing or have fewer than 10 minutes remaining on their duration.

• Lethal Poisons:
  • Left Click: Instant/Deadly Poison
  • Shift+Left Click: Wound Poison
• Non-Lethal Poisons:
  • Right Click: Crippling Poison
  • Shift+Right Click: Numbing Poison

Based on https://wago.io/NkU73VWfm/4 .

Caveats

If the trigger goes off in the middle of combat, this WeakAura goes a little wonky until it gets reset out of combat (e.g., with a UI reload, forcing the trigger to go off again, or opening WeakAura options). This is because the Blizzard API disallows frames from being hidden/shown during combat. One common workaround (as far as I can tell, based on Google searches) is to change the opacity of the frame, but this doesn't change the fact that the button, even when at 0% opacity, can still be clicked.

I think really, a better solution would be to keep a button for poisons on your action bar, and add a glow to it when the poison is absent or about to expire with another WeakAura (see https://wago.io/FFIqu9Ixk ). If you want to avoid the dropdown menu-like poison button from the spellbook, you can make a macro that does the same thing as this WeakAura:

showtooltip

/cast [button:2,mod:shift/alt/ctrl]Numbing Poison;[button:2]Crippling Poison;[mod:shift/alt/ctrl]Wound Poison;[spec:1]Deadly Poison;Instant Poison