I've recently started a mage character who uses followers (my other character is a thief who works alone). I'm still sort of getting used to having a follower around, and there are some things that I'm unsure about. For example, I'm not sure what potions my follower will or will not use if I give them to her (Lydia, atm). She will definitely use healing potions, but I haven't noticed if she uses stamina potions or not.

What I'm really most interested to know, though, is if she will use any poisons that I give her. I would love to have Lydia attack my enemies with weakness to frost/fire/shock/magicka poisons. Anybody know if it is possible to get a follower to do this?

Give her a poison, then see what happens after a battle. If the poisons are gone from her inventory, then she used them.

Followers will use whatever you have given them in their inventory as long as it is better than what they have stock. Just remember, the follower's skills and perks are factored into this.

All followers will try to use health potions when low.

Spell casters will use mana potions, but will often charge into melee instead, even if they only have fists.

I haven't seen anyone use stamina potions.

Followers will not use poison, but you can poison a weapon and give it to them, but that will only work for one hit and is generally not worth it.

Yeah, I've given them resistance potions, and they don't seem to use those either -- despite obvious situations where they would've benefitted from them.