No, but your attacks on minions splash, and they can hit a player even if you don't want it to. Not even accidentally.
(Also, if you wanna have fun, go for a tiamat on him, I do that when the team seems to warrant it, you do more damage to people you aren't hitting with the two splash. Although the extra range on his natural splash now makes the tiamat less appealing IMO)
Anby opinions on what to get Alistar, I figure I might as well make him a permanent addition so that I don't always use Janna. I tend to go with manamune, archangel staff, that mana regen chalice I forget the name of, hte cdr shoes, and then some attack speed/cdr if possible, but I'm still trying to tweak his item setup.