How to poison theself

Lingering damage health does indeed stack. I tested this by giving multiple lingering poisons to an NPC via the poisoner perk. Her health went down noticeably faster when I gave her multiple doses. I do not know how the duration is affected as she died before the poison ran out. I will report back later after I have found a suitably healthy target.

After some testing, here is what I found out:

• All the potion effects are applied simulatenously. So if you have a poison that does 2 damage for 20 seconds and one that does 1 damage for 10 seconds, for the first 10 seconds, the target will take 3 damage per second, and for the next 10 seconds, he will take 2 damage per second. The end result will be 50 damage.
• The same poison will stack with each other, 2 poisons of 1 damage per second for 10 seconds will do 20 damage in total over 10 seconds.
• The reason why some people think they won't stack is if you give an entire stack of poison to the target at one time (any amount >= 6), only the first poison in the stack will trigger. The rest will be given to the NPC and sit in their inventory as a potion that they now can use. If you want all the poison effects to trigger, you have to give it one at at time (and risk the 10% chance of detection at each attempt.)

This also leads to the question that if I use the Concentrated Poison perk in the Alchemy skill tree, are the effects the same as if I used two of the same poison in a row?

This is correct.

No it would not,game uses "trigger" to sedate you.It works on engine basis not gameplay basis.

There is just too much things that can go wrong if they equipped someone with 1st poison arrow and left it to attack first enemy,what if someone gets there and conjures creature to be hit by an arrow first?

Not to mention the character specifications as items,levels,bonuses,resists...