Which potions are valuable and which are not depends very greatly on your place within the game. When you first enter the dungeons, most potions provide some substantially useful effect. As you gain intrinsics or abilities, most become redundant or only marginally useful.

Recommended potions, in approximate order of desirability:

Table of potions Edit

Always useful

full healing When blessed, heals up to 400 HP and/or raises your max HP by 8; also cures illness and disease. Ascending with 6 or so provides a safe number of emergency outs, but save these for when you need them.
gain level When cursed, teleports you up one level. Useful for Moloch's Sanctum, Gehennom and emergency escapes. Can also substitute for potions of gain energy in alchemy.
holy water Increments BUC status of #dipped objects. This provides the most reliable way to bless an object or uncurse items that get cursed during the ascension run.
smoky (can be any type) Save, bless and quaff for the chance of a wish. A unicorn horn may be necessary to deal with ill effects.

Usually useful

extra healing Mid-game emergency heal, otherwise save and alchemize to full healing. If potions of gain energy are scarce, you can quaff them for +5 max HP instead of alchemizing.
healing Early-game emergency heal, otherwise save and alchemize to extra healing.
speed Without speed boots, useful for difficult combat. Otherwise, alchemize with healing potions to make extra healing.
gain energy Alchemize with extra healing potions to make full healing, or with full healing to make gain ability. Extras can be quaffed for a slight maximum energy gain.
gain ability Bless to raise all attributes by one point when quaffed.
enlightenment Bless to raise intelligence and wisdom by one point when quaffed. Alternatively, alchemize with levitation to make gain level. Also useful for verifying current intrinsics.
water #dip a stack into holy or unholy water to create more.
booze/confusion Useful for confusing yourself, then reading a scroll of gold detection to locate portals on the four Elemental Planes. More than four, or an alternate source of confusion render these unnecessary.
paralysis Throw or wield against powerful (sleep-resistant) enemies, then kill them before they recover.

Sometimes Useful

see invisible If you do not already have the see invisible intrinsic, or in an emergency if blind.
invisibility If you do not already have the invisibility intrinsic. Quaff one before eating a stalker to receive permanent invisibility and see invisible intrinsics.
unholy water Decrements BUC status of a #dipped item. Useful for cursing scrolls of genocide, teleport, and destroy armor, and potions of gain level.
sickness #dipped weapons will become poisoned. Lawful characters are penalized for striking with a poisoned weapon. Very useful with stacks of arrows and darts.
restore ability Superseded by a unicorn horn, but guaranteed to work.
monster detection Superseded by telepathy. Useful for finding where that nymph teleported to. If blessed, lasts several turns and detects mindless monsters as well.
object detection Useful when searching for vaults.
levitation Can be used to cross Medusa's level if found in sufficient quantities. Alchemize with enlightenment for gain level.
polymorph Can polypile a single stack of items.
oil Repairs weapon damage, recharges oil lamps and brass lanterns, untraps squeaky boards. Apply for a dim light source. Throw lit oil for a Molotov cocktail.
sleeping Superseded by wands of sleep.

Rarely Useful

fruit juice Can be quaffed for a small amount of nutrition.
hallucination Dip with a unicorn horn to make water. If you lack magic resistance (perhaps because of conducts), hallucination will protect against touch of death.
blindness Dip with a unicorn horn to make water. Throw at monsters to give them a small to-hit penalty and negate some gaze effects. Quaff it yourself if you need to avoid a gaze and don't have a blindfold handy.
acid Vegetarians can use these to cure stoning.
Community content is available under CC-BY-SA unless otherwise noted.