Potion

Potions are brewable items that imbue the consumer with specific, time limited effects in Minecraft.

Witches
Witches drop Potions of Healing, Fire Resistance, Swiftness and Water Breathing, but only when they die while drinking that potion.

Fishing
Water bottles may be caught as junk when fishing.

Filling bottles
Using a glass bottle on water source block or a cauldron that has water will turn it into a water bottle. Using a glass bottle on a cauldron that contains potion will turn it into a bottle of that potion. Using a glass bottle on a cauldron also removes $1/3$ of that cauldron's contents.

Brewing
Almost all potions can be obtained by brewing, starting with the water bottle as the base.

The Potion of Luck and the Potion of Decay cannot be brewed, and can only be obtained by commands such as, or through the creative inventory.

Natural generation
Two Instant Health II potions can be found in a brewing stand on ships in end cities, and one Potion of Weakness can be found in a brewing stand in igloo basements.

The cauldron witch huts contains a random potion.

Usage
Potions have a different effect according to their damage value, with the exception of reverted potions being identical to their base potions.

Potions can be used by pressing and holding, similarly to eating food. Upon using, they will apply the corresponding status effect to the player.

Tiers
Potions have four tiers, those being base, extended, level II, and reverted. On most potions, extended is obtained by adding a piece of redstone to the potion in the brewing stand, while level II requires a glowstone dust. If an extended potion receives a glowstone dust, or a level II potion receives a piece of redstone, it will change to the other effect if available, or become a reverted potion.

Most potions can also be "corrupted" using a fermented spider eyes, which usually inverts the effect (for example: Swiftness to Slowness). Corrupted potions have the same four tiers as normal potions, and tiers are usually kept after corruption.

Base potions
Base potions are potions that are created first to brew into other potions. Base potions have no effect when you drink them.

Primary potions
Note, that the duration of tier II potion is always half the duration of its base potion, and the duration of extended tier I potion is 8/3 the duration of base.

Unbrewable potions
This class of potions exist in the game code and are functional, but cannot be brewed or be found in the Creative Inventory. They are extended and empowered versions of existing potions, but the brewing process normally only allows for one of the two to take precedence. Thus, these potions result from custom data values that place both effects on the potion. The data values for these potions are essentially the values of the original potions added by 96 (e.g. the data value for Potion of Strength (8201) + 96 = 8297 (the data value of Potion of Strength II (extended))) See the table below for the complete set of what is included.

Unused potions
The uncraftable potion is a potion with no effect that is unobtainable in survival. It is also available in splash potion and lingering potion forms, as well as for tipped arrows. Its use is unknown.

It can be obtained using the following command:. It is also obtained any time a potion has invalid or missing potion effect tags.

Filling cauldrons
Using a potion on a cauldron will add one level of that potion to the cauldron. Attempting to add a potion to a cauldron with water, dyed water or a non-matching potion will empty the cauldron.

Using a water bottle on a cauldron will add one level of water to the cauldron. Attempting to add water to a cauldron with potion will empty the cauldron.

Custom effects
Potions can be obtained with any status effect using and the tag , which is an array of effects for the potion. See Item format for more information, and status effect for a list of effects and IDs.

Data values
Potions have a data value of 373, and an ID name of. They use their item data to determine which potion effect is applied.

Item data
Potions use an NBT "Potion" tag to indicate the potion type. The values of the tag (to be prefixed with ) are:

Trivia

 * Taking a potion while already under the effects of the same potion does not add onto the effects time, but simply resets it. A potion effect will not "downgrade" if a lower level is activated. For example, if a player has Regeneration II, drinking a regular Potion of Regeneration will not have any effect.
 * A potion can reach a maximum tier of 127, but using the command, effect levels can reach 255.
 * When a player drinks two potions by quickly switching to another potion immediately after drinking one, the second drinking animation will not be shown.
 * An Instant Damage IV potion is powerful enough to instantly kill players.
 * Potion of Poison II lasts for 22.5 seconds, but it is displayed as 22 seconds because the item hover display only shows rounded-down integer values.
 * All potions are renewable. The bottles can be obtained from a witch (as can some potions), Glass can be purchased from Librarian Villagers to craft into bottles, and already filled ones can be fished up. All potion ingredients from then on have renewable ingredients, provided blocks of farmland, water and soul sand exist in the world.
 * Potions of Harming will not harm undead mobs (Zombies, Skeletons, etc.) and instead heals them. Likewise, Potions of Healing will damage undead mobs.
 * Potions of Poison and Potions of Regeneration will not harm undead mobs, but will not heal them either.
 * If you use Night vision potion in the End, the Endermen and Ender portal will appear to be white when far enough away.