Does Caustic's gas affect teammates?

Do Caustic's gas traps or ultimate gas grenade affect my teammate movement speed or do damage?

I haven't heard my teammates complain about it. Also I can't test it with my friends because they don't have the game.

The gas trap definitly affects team mates movement speed, though not in a good way

As far as I can tell, it does not deal damage. I actually doubt that friendly fire is in any way possible (maybe through Bangalore & Gibraltar ultimate). It also reduces vision, just like Bangalore's smoke grenade.

As I don't own Caustic, I can't tell if a friendly Caustic is affected the same as any other friendly character. Also I am not certain about Caustic ultimate gas grenade, yet I would assume it to behave the same way

This is all based on my own experience within the game.

Caustic main here, quick answer is : Nope, it doesn't, the only thing that affects is their visibility,even Bloodhound is affected in this one.

It affects them the same way it affects enemies, except without doing damage. Same with his ultimate.