A Westbrook woman pleaded guilty Thursday to charges that she purchased a bottle of fish oil capsules from a pharmacy, replaced some with stool softener capsules and anti-seizure medication, and then returned the bottle the next day.

Kathy Jordan, 61, pleaded in U.S. District Court to one count of adulterating a food item with intent to defraud.

She will be sentenced at a later date but faces up to three years in prison and a $250,000 fine.

According to the U.S. Attorney’s Office, Jordan purchased the fish oil and two other items on April 3, 2012, at a pharmacy near her residence. She then returned all three items the next day for a full refund.

A week later, the U.S. Attorney’s Office said, the fish oil capsules were resold to another customer. That customer noticed that the bottle contained other capsules in addition to the fish oil and brought the bottle back to the pharmacy.

The retail store contacted the Food and Drug Administration’s Office of Inspector General to investigate.

Jordan told investigators that she opened the fish oil bottle and removed some capsules but then replaced them with stool softener capsules and some of her Dilantin, an anti-seizure medication, so she could get a full refund.