"Livid" and "baffled" customers have been complaining to Boots after receiving their prescriptions in plastic bags rather than paper ones.
One was so incensed she took her bag back to the store with "shame on you!" and "paper, not plastic!" written in capitals in black marker pen.
Boots said it was using plastic bags because some prescriptions are now assembled at a central location, rather than in local pharmacies.
Plastic was "more durable", Boots said.