All Status Effects result from a build up of attacks that render that said effect. Once the gauge meter has been filled, the status effect will be applied to either the player character or the enemy.

Poison:

Once the meter is filled, you will take slow continuous damage over a period of time.

Deadly Poison:

A much stronger form of Poison, the meter is filled much faster and deals greater damage over a period of time.

Scarlet Rot:

Once the meter is filled, you will take damage over a period of time.

NOTE: 

While Scarlet Rot and poison may seem to have the same effect at first glance, Scarlet Rot deals more damage over time.

Performing a dodge roll in a pool of either scarlet rot or poison will increase its buildup speed and will not decrease until it fills up the meter.

Blood Loss:

You will bleed out and take a large amount of damage relative to your Max HP.

Frostbite:

You will take damage and become frostbitten for a while. While frostbitten, you will take increased damage from other sources and recover stamina slower.

Sleep:

You will become drowsy until the gauge fills up, which then puts you to sleep. Weaker characters will fall asleep instantly.

Madness:

Similar to Frenzy from previous Souls games, you will go mad and lost a great deal of both HP and FP.

Death:

Once inflicted with Death, you will be struck down instantly and must revive at a Site of Grace.