Original site: http://www.xs4all.nl/%7Ebrt/wow/guides/skillupalchemy.html
Please visit his site for the full unabridged guide.

This is a condensed version of Ithilian's excellent Alchemy levelling guide.

1 - 60
Minor Healing Potions (1 x Peacebloom, 1 x Sliverleaf, 1 x Empty Vial) x 60

60 - 110
Lesser Healing Potion (1 x Minor Healing Potion, 1 x Briarthorn) x 50

110 - 140
Healing Potion (1 x Bruiseweed, 1 x Briarthorn, 1 x Leaded Vial) x 30

140 - 155
Lesser Mana Potion (1 x Mageroyal, 1 x Stranglekelp, 1 x Empty Vial) x 15

155 - 185
Greater Healing Potion (1 x Liferoot, 1 x Kingsblood, 1 x Leaded Vial) x 30

185 - 210
Elixir of Agility (1 x Stranglekelp, 1 x Goldthorn, 1 x Leaded Vial) x 25

210 - 215
Elixir of Greater Defence (1 x Steelbloom, 1 x Goldthorn, 1 x Leaded Vial) x 5

215 - 230
Superior Healing Potion (1 x Sungrass, 1 x Khadgar's Whisker, 1 x Crystal Vial) x 15

230 - 250
Elixir of Detect Undead (1 x Arthas' Tears, 1 x Crystal Vial) x 20

250 - 265
Elixir of Greater Agility (1 x Sungrass, 1 x Goldthorn, 1 x Crystal Vial) x 15

265 - 285
Superior Mana Potion (2 x Sungrass, 2 x Blindweed, 1 x Crystal Vial) x 20

285 - 300
Major Healing Potion (2 x Golden Sansam, 1 x Mountain Silversage, 1 x Crystal vial) x 20

Approximate Materials Required:

60 x Peacebloom
60 x Silverleaf
75 x Empty Vial
80 x Briarthorn
30 x Bruiseweed
65 x Leaded Vial
15 x Mageroyal
40 x Stranglekelp
30 x Liferoot
30 x Kingsblood
45 x Goldthorn
5 x Steelbloom
70 x Sungrass
15 x Khadgar's Whisker
90 x Crystal Vial
20 x Arthas' Tears
40 x Blindweed
40 x Golden Sansam
40 x Mountain Silversage
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Alchemy 300 to 375 Guide by Highlander on EU-Terenas

300 - 310
Volatile Healing Potion (1 x Golden Sansam, 1 x Felweed, 1 x Imbued Vial) x 10
N.B. You can make Major Mana Potions up to this point if you prefer. You'll need to make about 25 though.

310 - 325
Elixir of Healing Power (1 x Golden Sansam, 1 x Dreaming Glory, 1 x Imbued Vial) x 15

325 - 350
Mad Alchemists's Potion (2 x Rageveil, 1 x Crystal Vial) x 40
Turns yellow at 335, but it's so cheap to make, just make it until it turns grey at 350.

350 - 375
Major Dreamless Sleep Potion (1 x Dreaming Glory, 1 x Nightmare Vine, 1 x Imbued Vial) x 40
Goes green at 370, but it's easier to skill up on this, now that it's in the game, than use low drop rate

recipes or faction rewards.
Can be bought from Leeli Longhaggle in Allerian Stronghold (Terokkar Forest) for Alliance and from Daga Ramba in

Thunderlord Stronghold (Blade's Edge Mountains) for Horde players.

Approximate Materials Required

35 x Golden Sansam
10 x Felweed
65 x Imbued Vial
80 x Ragveil
55 x Dreaming Glory
40 x Nightmare Vine
40 x Crystal Vial