“KNOCKED UP” star KATHERINE HEIGL demands $6 million from drug store chain after unauthorized photo use.

Heigl hit Duane Reade Inc. (who owns ginormous drug store chain) with a $6 million lawsuit in New York federal court Wednesday.

Heigl claims claiming the company unlawfully used an unauthorized photo of her for commercial advertising and distributed it through its social media accounts without her knowledge or approval.

Heigl charges  that despite sending a cease-and-desist letter, the pharmacy chain has refused to stop its alleged misuse and misappropriation of the photo.

The photo in question was taken in March without the actress's consent by New York paparazzi after she left a Duane Reade.

The image first popped up March 18 on a Tweet on Duane Reade’s official page, saying “Love a quick #DuaneReade run? Even @KatieHeigl can’t resist shopping at #NYC’s favorite drugstore.”

Duane Reade has since ignored Heigl’s pleas to stop the “false advertising” on its social network accounts, which reach “millions of customers,” the suit claims.

Heigl’s suit reads more like a resume in some parts.

The suit says she’s an award-winning “highly successful television and motion picture actress, producer and celebrity” and then offers a long list of her film and TV credits that also include “The Ugly Truth” and “Knocked Up.”

“As a consequence of her work in the entertainment and philanthropic worlds, plaintiff is a highly recognized celebrity,” the suit says. “… Accordingly, when plaintiff chooses to endorse a product or service, she is highly selective and well compensated.”

Heigl says she’s not looking to profit off the suit to subsidize a flagging career.

The animal-loving thesp says in the suit that any money reward she receives would be donated to the Jason Debus Heigl Foundation, an animal-welfare charity that she and her mother set up in honor of her late brother, who was tragically killed in a 1986 car accident.