Credit: Jason Merritt/Getty Photo: Katherine Heigl at the Compassion Revolution Press Conference

A mundane trip to the drugstore could net Katherine Heigl $6 million, if she wins the lawsuit she just filed against pharmacy chain Duane Reade.

The former Grey's Anatomy star takes issue with Duane Reade's use of a March 16 paparazzi photo of her leaving one of the chain's New York City locations with bags in hand. (She's in the Big Apple to film her new NBC pilot, State of Affairs.)

Duane Reade tweeted the photo with the caption, "Love a quick #DuaneReade run? Even @KatieHeigl can’t resist shopping #NYC's favorite drugstore."

Per Reuters, the lawsuit claims that Katherine is "highly selective and well compensated" in her choice of product endorsements — and that she did not authorize any endorsement of Duane Reade.

Gawker reports that Katherine asked the company to remove the tweet before getting litigious. Interestingly, the tweet remains online even now.

"We expect Duane Reade to pay for its willful misuse of Katherine Heigl's name and likeness," says Peter Haviland, Katherine's lawyer.

But apparently, the 35-year-old actress isn't taking Duane Reade to court to pad her wallet. Any proceeds won in the suit will go to her animal-advocacy charity, the Jason Debus Heigl Foundation.

Do you think Katherine is entitled to the $6 million? Sound off in the comments below!

Sources: Reuters, Gawker

Dan Clarendon is an assistant editor at Wetpaint Entertainment. Follow him on Twitter and Google+!