Just what are poison arrows any use for?

I've got a fair stock of these things but not once have I found them to be effective. Maybe I'm using them on the wrong enemies but I've tried them on just about everything without any success. I'd be grateful for any tips.

Target Lock and shoot PvPers with them. Offhand the bow and have a buffable weapon as your main hand then use Poison Resin, it stacks.

well the poison arrows are realy helpful in a lot of ways specially pvp where they can be used to descract your opponent making him/her make stupid decisions...in pve they can be used to take down enemies but u must 1st know wht enemies are resistant...it can be used to take out the 2 white knights with dsbows in londo n it can be used to take out drakes in the valley

I use them pve all the time. Very useful against the demons in the Ruins. Only the small round ones are immune.

Oh the many uses. Where are you? I use 'em all the time.

Some enemies have intentionally been made with low resistance against poison. The greatbow guards on the outside of the cathedral can be poisoned with 1 or 2 arrows, but the others can't. The boars guarding the entrance to the archives is also infected with 1 or 2 arrows. Gwyndolin only takes a few arrows as well. I usually dungpie the forest cats for a faster kill, but I think you can poison them as well.

I find the poison arrows quite usefull on the things in Demon ruins uhm...the..hmm...Centrepies? Those things coming up from ground/ Out from walls/Roofs. Great help if you don't want to risk getting eaten.

I use poisin arrows on the giants guards and giants they die fairly quickly too.

They lose a lot of efficacy in NG+ and beyond but even then they are great for getting a snack and coming back to a corpse/weakened enemy.

Giant Guards in Anor

The demons in the Ruins

The Archers in Anor

....on and on and on....

I use them all the time. I tend to use them a lot in Sens and Anor Londo, but really could be used anywhere. 2-3 arrows then move to the next enemy as those whittle down the HP.

Poison arrows in Demon Ruins = Dead Taurus demons + dead Capra demons + Sandwich + protected treasures + stretched legs

A rule of thumb with poison arrows if it has flesh and it can bleed then it probrably can be poisoned (unless the thing you are trying to poison is in blighttown)

I use them when I invade. I have one character I use specifically to troll people a bit. Uses a bow in the offhand to get my opponent to turtle, then I pull out my main hand shotel and kill them through their shield! Poison arrows come in handy to control people's behavior. When I want someone to turtle, I use fire arrows, since they're strong and scary! But when I invade a group of 3 and they're sticking together, I'll use poison arrows to force the phantoms into getting aggressive. That way I can kill them and take my time with the host!

Well, I must have a defective bow or something because they don't work for me. I've tried them on all of your suggested enemies and nothing happens. I used them a lot in Demon's Souls, especially Red Eyed Knights and it was great to see their health trickling away, even through a wall. I've never seen this happen in Dark Souls, so maybe it isn't there to start with, although if I use Poison Cloud, I can see the results.

P.S. Thanks for all your replies though.

For a lot of enemies you'll need to hit them a few times to start the poison rolling. If you're in NG the poison will kill a lot of enemies once activated but in NG+ you might have to reapply. As long as the arrow hits it will start the poison meter rolling whether the arrow does any damage or not. There should be a little blood graphic or something that shows the arrow hit. I was able to poison the Capra demon just before the Chaos shortcut exit from the ledge just past where Kirk invades. Tip for cheaper poison kills. Buy standard arrows at 1/10 the cost and use these to target enemies at range. Once you see the blood graphic switch to poison arrows to do the deed. This helped me in NG when souls could be tight at 100 per arrow. Another rule of thumb, if four or five arrows don't poison, find another way to kill it.

You need to hit them 2-3 times in succession to get the poison built up. Just like when you get poisoned it takes a few hits to fill up your bar. Even though you don't 'see' a bar on your enemies, it is still there and usually requires multiple hits.

Poison arrows in PvP suck, their damage it's negligible, only noob/newbies get nervous when poisoned and try to eat Purple moss. Toxic it's almost the same, because it also has negligible damage but, contrary to Poison, it does very well damage at low levels. Also most players have moss in their quick inventory so....

In PvE poison arrows can work to kill common or slow enemies from a distance, if you have the patience. It's useless against bosses because most of them are immune and the ones who are not (if there is any) it's melee and will kill you before he dies of poison.

s&o, fire sage, stray demon, gargoyles, taurus demon, capra demon, sif (unconfirmed) these are the poisonable bosses, due to their large health bars its not much use unless you can alter the battle into a attrition match etc. note: the gargs take around five shots as does S&o. my dads had success using poison arrows on big smough at lvl 9 and just kiting him into pillars thus prolonging his miniscule health bar.

In the forest, poison causes major panic to gankers

I use them a lot, particularly in areas where I am waiting to be called to duty to fight a boss and I'm just hanging out. As others have pointed out, this is especially awesome in Demon Ruins. I will run around, fill everything I can see with poison and then sit back and wait, get snack or beer, go potty, etc.

As others have also said, you sometimes need to pump them with multiple arrows. For many creatures, you will here a sizzle and see a mist around them, telling you that they are poisoned. I think that sometimes the geometry of the bigger creatures makes this less than obvious.

You will also see the bar, although not always. I think it's a little buggy, depending on where your frustum is aimed.

O.K. thanks, I'll not give up on them yet then. Interesting, I didn't know that you have to use more than one arrow. I'll give it a try.

I wanna say I found something that takes four to poison. Taurus in demon ruins are three each as are halberd giants in anor londo.

Headshots seem to decrease the amount of arrows you need to use. I poison all the capra demons in the ruins and just wait for them to collectively drop.