Carol Door was last seen on Monday morning, leaving her home in Frank Avenue.
It is thought the 42-year-old could have travelled to the Northumberland area.
She is described as being white, 5ft 7in tall, with short, dark brown hair. She was wearing a long black coat, blue jeggings and a white woolly hat and was carrying a black over the shoulder handbag.
Sgt Chris Spencer, from Durham Constabulary, said: "We are becoming increasingly concerned for Carol, as this is very out of character for her."
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Anyone who has seen Carol, or knows of her whereabouts, is asked to call Durham Constabulary on 101, quoting incident number 314 of February 11.