For anyone interested, there is a list of all Kingdom Come Deliverance alchemy recipes with the effects of each potion ! Pretty helpful if you don’t know how to make your potions or Henry doesn’t know how to read yet.
When you create a potion, it is automatically added to your alchemy book. There are potions to boost his life, make Henry stronger or heal him from the poison.
You can read all of Kingdom Come Deliverance’s alchemy recipes here: http://kill-the-game.com/kingdom-come-deliverance-a-list-of-all-the-recipes-of-alchemy-how-to-create-potions/