Board Thread:Dark Souls/@comment-6003396-20130223070747/@comment-6003396-20130224103249

So, from what I have tested so far, it seems that the only constancy for Poison and Toxic is its duration. Poison is 3 minutes and Toxic lasts 10 minutes, regardless of where it was contracted.

But, here is where it gets a bit more complicated. Depending on its source, it will cause varying damage per second. For example:

Toxic Poison
 * Dung Pie: 7/second
 * Gravelord Sword: 5/s
 * Dark Silver Tracer: 6/s
 * Toxic Mist: 6/s
 * Poison Swamp: 4/s
 * Mosquito: 9/s
 * Dark Fog: 4/s
 * Poison Mist: 3/s

The damage is the same regardless of the Poison Resist, Level or total HP of the victim. Poison/Toxic damage by enemies appears to be the same for NG and NG+.

Poison Mist and Toxic Mist cause the same amount of damage regardless of the level of the Pyromancy Flame. Similarly, Dark Fog seems to cause the same amount of damage regardless of magic adjust, but I suspect that magic adjust plays a roll in buildup.