Source: Dungeon Master's Guide

Potion, rarity varies

You regain hit points when you drink this potion. The number of hit points depends on the potion's rarity, as shown in the Potions of Healing table. Whatever its potency, the potion's red liquid glimmers when agitated.

Potions of Healing
Potion of … Rarity HP Regained
Healing Common 2d4 + 2
Greater healing Uncommon 4d4 + 4
Superior healing Rare 8d4 + 8
Supreme healing Very rare 10d4 + 20