Unless specified, effects from the high last 3 minutes and effects from the crash last 2 minutes. The crash will kick in once the high is over.

Skooma
High: +80% StamRegen
Crash: -30% StamRegen, -30% MagRegen

Double-Distilled Skooma
High: +100% StamRegen for 210 seconds
Crash: -20% StamRegen for 120 seconds, -20% MagRegen for 120 seconds

Redwater Skooma
High: +250% StamRegen
Crash: -60% StamRegen, -65% MagRegen

Hist Sap Skooma
Argonian High: +40% 1H/2H damage, +160% StamRegen
Non-Argonian High: +20% 1H/2H damage, +160% StamRegen, -50 Max Health for 1 minute
Crash: -50% StamRegen, -30% MagRegen

Cleansed Skooma
High: +60% StamRegen
Crash: -5% StamRegen

Ghostveil Skooma
High: Look like a ghost for 1 minute, +60% StamRegen, +20% SpeedMult
Crash: -40% StamRegen, -5% SpeedMult

Black Lotus Skooma
High: +90% StamRegen, Poison Cloak does 3/s damage to enemies that get close for 45 seconds, -25 Max Health for 1 minute
Crash: -40% StamRegen, -35% MagRegen

Minstrel's Skooma
High: +120% StamRegen, +15% XP gain for 1 hour, prices are 20% better
Crash: -40% StamRegen, -30% MagRegen, prices are 25% worse

Icebane Skooma
High: +80% StamRegen, +100% MagRegen, +70% Resist Frost, -7% SpeedMult
Crash: -45% StamRegen, -40% MagRegen

Fireblood Skooma
High: +120% StamRegen, +70% MagRegen, +100% Resist Fire for 20 seconds then changes to +40% for 160 seconds
Crash: -40% StamRegen, -30% MagRegen

Mad Cat Skooma
High: +350% StamRegen, Slow time by 50% for 20 seconds
Crash: -50% StamRegen, -40% MagRegen

Venom Skooma
High: +80% StamRegen, -20 Max Health for 20 seconds, +100% Poison Resist
Crash: -30% StamRegen, -30% MagRegen

Berserker's Skooma
High: +250% StamRegen, +25% AttackDamageMult, +25% WeaponSpeedMult
Crash: -75% StamRegen, -35% MagRegen, -10% AttackDamageMult