User blog comment:EvanDude345rv5/Fairy Tail Chapter 358 Review : Magical Barrier Particles/@comment-117.227.52.242-20131103003505/@comment-7418318-20131103081907

Considering how she said that to Demons poison is a treat, I think she is as resistant to poisons as Cobra (while in Take-Over anyway), except that she probably doesn't get a magic power boost from eating poison.

But as B214 pointed out, it's not a normal poison, so I highly doubt even Cobra is immune.

There might be a small chance that Mira's Satan Souls could be, if Tempesta's ability is made in a way that it doesn't affect other Demons, but I somehow doubt it.