An off-duty NYPD officer working a side job as security at a Midtown Duane Reade was punched in the face Sunday morning while trying to stop a shoplifter from stealing beer, police said.

The cop was keeping watch at the drug store on Broadway between West 35th Street and West 36th Street at around 7:20 a.m. when she was alerted that a man was trying to take beer out of the store without paying, according to police.

When she confronted the thief, he punched her in the face and then ran off, cops said.

The officer was taken to NY Presbyterian Hospital by ambulance and treated for scratches on her face, police said.

The suspect was described as standing 5-foot-8-inches with a beard and wearing a brown coat, gray pants and black and white sneakers, cops said.