Have you ever felt that Minecraft's 'poisonous' items aren't impactful enough? Do the built-in effects just not cut it anymore? Do you want absolute suffering for those who dare to ingest your modded items?

Nothing on its own. It's a library mod, meaning that other people use this to make their mods do stuff.
It's like Radioactive - It's mostly for modpacks and such, and uses the same systems.
Details TBC - Mod in development
They hurt you. That's basically the definition of toxicity, but this mod does a bit more than simple eat-it-and-die stuff.
The longer a toxic item is in your inventory, the worse effects you get:
First, minor effects like slowness and nausea, then weakness, poison and even wither.
Mod suggested by Kirillpro300O