It’s a lost Claus.

A SantaCon reveler who landed in a coma after falling down a flight of stairs at a Manhattan bar only has himself to blame for the drunken tumble, a judge ruled.

Manhattan Supreme Court Justice Barbara Jaffe tossed a personal injury suit brought by sozzled Santa Christopher Visone against the since-shuttered Third Avenue Tavern over his Dec. 14, 2014 fall.

“Providers of alcohol owe no duty to protect against the consequences of one’s own voluntary intoxication,” Jaffe said in her ruling.

Visone, 32, a sales rep from the Bronx, admits to downing at least five drinks at that year’s SantaCon — an annual spectacle where participants don St. Nick outfits and storm city bars en masse to guzzle grog.

But he insists he fell backward down about 20 steps at the Kips Bay sports bar because he slipped on something in the stairwell.

“The bar was messy,” Visone told The Post. “I have to think [the fall] was due to the condition of the stairs.”

Visone wound up in a medically induced coma for weeks while receiving treatment for a traumatic brain injury.

His attorney argued the bar should have posted a guard at the top of the stairs to protect patrons — but the judge just scoffed at the idea.

“I mean, I’ve never heard of that,” Jaffe told lawyer Denny Tang during a hearing over the summer.

Visone’s medical records indicate that the fall was “alcohol related,” and his blood-alcohol level was 0.34 — over four times the legal limit, said the bar’s attorney, Andrew Funk.

“This gentleman went out to SantaCon. [He was] partying since 10 a.m. or 11 a.m. — it was 1 a.m.,” Funk said. “He had a huge blood alcohol level and he just passed out and fell down.”

Jaffe agreed after finding no evidence of a spill or other items left on the stairway.

Visone claims to have had only one drink at the tavern between arriving at 10 p.m. and leaving three hours later — but argued that if he had been that wasted, the watering hole should never have let him in.

But the judge said he couldn’t have it both ways — noting in her ruling that an expert for Visone “contradicts himself by characterizing plaintiff as too drunk to be in the bar, but not too drunk to walk down the stairway safely absent any dangerous condition.”

Meanwhile, Visone is still suffering from the spill four Christmases later.

He’s on five medications — including two that prevent seizures — and says he’s a “changed person.”

“I don’t drink,” he told The Post. He now thinks SantaCon should be banned for encouraging dangerous drinking.

“Kids do it as an excuse to drink and I’m very opposed to it right now,” he said.

Still, he’s appealing the ruling, because he insists the bar did not keep the stairway clean. His suit seeks unspecified damages.

SantaCon, an international event that started in San Francisco in 1994 and spread to New York a few years later, is known to many locals as an annual nightmare that results in hordes of drunken bros puking, peeing and punching in the streets.

The Long Island Rail Road, Metro-North and NJ Transit now ban alcohol on their trains during the Kris Kringle crawl, while many Big Apple bars refuse to serve costumed carousers.

In 2015, the NYPD arrested five SantaCon revelers — including a woman who threw a beer mug at an East Village bartender — and issued 100 summonses.

This year, New York’s Finest made two arrests and issued 50 summonses.

But Hoboken’s notoriously rowdy version saw 14 arrests — and four cops sent to the hospital.