Xanax, Adderall, Vicodin -- We're Gonna SUE Over Kitson Druggie T-Shirts

Three major Rx companies are now gearing up to sue a famous L.A. clothing boutique for jacking their product names on snarky jerseys.

Kitson in L.A. is selling shirts emblazoned with popular prescription drug names like Xanax, Vicodin, and Adderall -- drugs that are widely abused and responsible for many deaths.

The people at DrugFree.org have already expressed anger over the shirts ... but now reps for Xanax, Vicodin, and Adderall tell TMZ, they're scrambling lawyers to get the shirts yanked from the shelves ... OR ELSE. The "or else" is a trademark infringement lawsuit.

Adderall's rep tells us, "We had no involvement NOR do we approve of the sale of such a product using Adderall to glorify the misuse of our product."

Vicodin's rep adds, "Prescription drug use should not be trivialized. It is a serious issue and we will be taking legal action to stop the clothing company from trying to sell such a product."

A Xanax rep tells TMZ they're also considering legal action.