CHELSEA — Rapper Busta Rhymes threw a protein shake at a gym employee after a long-simmering dispute boiled over Wednesday night, police said.

The drink cut the man's head and Rhymes was arrested at Chelsea's Steel Gym on West 23rd Street, police said.

Thanks to everyone who helped expedite this evening for me. I'm good and we're back to the grind. Heading 2 the studio 2 turn the bullshit into GREATNESS. I'm super good. #THECONGLOMERATE. A photo posted by Busta Rhymes (@conglomerateent) on Aug 5, 2015 at 11:29pm PDT

The rapper, whose real name is Trevor Smith, was in the gym about 8:24 p.m. when he and the employee started arguing, an NYPD spokeswoman said.

The rapper had a longstanding problem with the worker, whose name and age were not immediately released, police said.

The feud escalated when the two started dousing each other with water, police said.

Busta then threw a Lean Body protein drink at the worker, police said.

The victim refused medical attention at the scene but suffered bruising, swelling and substantial pain, officials said.

Busta, who rose to stardom as a flamboyant member of the '90s rap group Leaders of the New School before continuing on to a high-profile solo career, was arrested at the scene, police said.

Busta, of Long Island, was charged with assault and released. He's due back in court on Nov. 6, prosecutors said.

He posted to Instagram afterwards thanking those who helped him expedite his release.

Busta has been arrested seven other times in New York City, NYPD officials said.

He was arrested in 1998 for carrying a gun and again in 2006 on gang assault charges, police said.

He was arrested three separate times in 2007 for driving while intoxicated, driving without a license and assault, police said.

He also has two sealed arrests.