According to legal docs filed Tuesday, obtained by TMZ, Leah -- who also starred on the 'Housewives' spinoff 'Ultimate Girls Trip' -- claims the producers ... along with Bravo, NBC Universal Media and others created a toxic work environment where her mental health and alcohol use disorder were exploited all in the "name of selling drama."

She goes on to allege Andy and others were pressuring her to consume alcohol during her time on the show -- despite knowing of her addiction struggles. As one example, Leah points to a text message she says she got from 'RHUGT' costar Marysol Patton saying, "I wish you were still drinking" -- which Leah took as a clear reference to her newfound sobriety.

The reality TV alum also claims that the "Watch What Happens Live" host uses cocaine with other Housewives and Bravo stars -- and allegedly rewards those who participate in the drug use with good TV edits.

A rep for Andy Cohen tells TMZ … "The claims against Andy are completely false."

Leah is suing for unspecified damages, claiming the production discriminated against her based on her known alcohol problem and other issues and failed to make any accommodations during her time on the shows.

This lawsuit comes amid other 'Housewives' drama for Andy -- who has been accused of sexually harassing "Real Housewives of Beverly Hills" and 'RHUGT' alum Brandi Glanville.

ICYMI ... last week, Brandi's lawyers sent a letter to NBC Universal threatening a lawsuit -- in which the Bravo honcho was accused of inviting Brandi to watch him hook up with another Bravo personality over FaceTime.

Andy quickly responded to Brandi's claims ... writing on X that the whole thing was a joke that has been blown out of proportion. However ... he did acknowledge that the situation was inappropriate.