Poison

Damage over time, but it never takes the last half heart. Undead mobs are immune.

Potions

Potion	Level	Drink or splash	Lingering	Tipped arrow
Potion of Poison	I	0:45	0:11	0:06
Potion of Poison (long)	I	1:30	0:23	0:11
Potion of Poison II	II	0:22	0:05	0:03