It is hard to imagine a time when a Potion of Healing was a novel idea, but way back in 1974 when the first edition of Dungeons and Dragons (OD&D for Original D&D) came out this was blazing new ground. Of course today you would be hard pressed to find a fantasy rpg without a potion of healing. This is my take on a classic.
The potion of healing has changed very little from its appearance in Monsters & Treasure (volume 2 of the original three booklets that comprised OD&D) all the way up to the current (5th) edition of D&D (D&D 5e). Of course there have been way more than five editions of D&D but that is a post for another day. Many magic items have changed quite a lot over the years- magic swords in particular, did you know that all magic swords were intelligent, had an alignment (law, chaos or neutral) and had an ego in the original edition?
Contrast that with the potion of healing - here is the text from OD&D and the text from D&D 5e:
OD&D Potion of Healing: A Healing potion repairs one six-sided die, plus one, (2-7) points of damage, just like a Light Wound spell.
D&D 5e Potion of Healing: 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. Potion of Healing (Rarity - Common): 2d4+2 HP Regained.
I think this is a case where I don't like the added fluff RE the red liquid. Of course I ignore such things, but IMO it takes away from the mystery of magic items if it is suggested that all potions of healing are a red liquid which glimmers when agitated. Plus I have always imagined them as blue with a silvery gleam when agitated :)
Cheers - Carl