"I'm drinking again … I'm a drinker, I drink a lot," the 41-year-old actor said, adding that he was hesitant to open up because of the negativity generated by others about his addiction issues.
When Stern asked him if he was doing drugs in addition to the drinking, Arquette hesitated before admitting, "Yeah, I'll smoke a little weed."
The Dancing with the Stars personality, who's been to rehab before -- and publicly celebrated his sobriety milestones -- said he just decided to go back to the bottle upon "feeling like I wasn't being that true to myself.
"I'm a wild man, I do get out of control, I try to keep a cap on it," he said, adding that he's never been one to get behind the wheel after throwing back a few.
When the Private Parts star asked the actor about his girlfriend Christina McClarty, and how she's handled his relapse, he said, "My girlfriend's cool, she supports me. She's cool."
Asked how his ex Courteney Cox has reacted to his lost sobriety, Arquette said "everybody's getting along."
The King of All Media told Arquette, "I'm worried about you, only because I know you got a problem with alcohol."
Arquette answered him, saying, "Whatever I do, I'm gonna do: I'm gonna go through this journey and figure out my life.
"I'm a responsible person, I have my daughter three days a week ... I'm incredibly responsible. I'm living my life and I'm trying not to hurt people."
Stern asked Arquette about our report that he was let go from the film Something About Her due to his relapse.
"They're the same people that are up my a** and they're probably gonna write about this too," he correctly predicted. He said that after three days of working on the film, he was working with Anthony Michael Hall and realized that the Edward Scissorhands star was a better fit for the role than he was.
Arquette said the parting from the film was amicable, as "the director wasn't happy with his performance, and he has his own vision for it, so I get it."
Throughout his appearance, a raspy-throated Arquette said that in an epiphany, he came up with an idea he named "The Kindness Game" -- the concept that being nice toward others will be a form of currency in the future.
Asked about his lack of a voice, Arquette said that he lost it while singing at one of his clubs. Stern said he thought being around the club environment caused him to slip off the wagon.
"It is hard," Arquette said, noting that the lifestyle is all about celebration and revelry.
Stern asked the star how many drinks he consumed the night he lost his voice; Arquette responded, "I don't know probably had about four or five drinks … vodka, and I get strong drinks, but it wasn't like I was stumbling around … I had a driver, I wasn't like a knucklehead."
Arquette repeatedly reverted back to stressing how the world was not a nice one these days, saying that he was afraid to be too honest with the radio personality "because people can be so cruel.
When an aggressive caller told the actor he was "full of s**t" -- and asked him how he thought his drinking would have a trickle-down effect on his daughter Coco -- Arquette acknowledged that being a parent ties into his own responsibilities, to how he has to keep things under control.
"I got my own problems, yes, and I will sort them out," Arquette said, adding that he sees a therapist.
Stern said he has friends who have gone back to drinking after being sober and some can cope while others can't.
"That's the question," his sidekick Robin Quivers chimed in. "Which group is David in?"
The Howard Stern Show airs on Sirius XM weekdays.