A man who suffered burns to his hand after spilling lighter fluid on it said his injury was treated and wrapped in a supermarket freezer bag.
Nicholas Robertson, 38, was treated for the burn at the University Hospital of Wales, Cardiff.
Mr Robertson said he was stunned to find his hand had been wrapped in a supermarket freezer bag.
The hospital is investigating, adding it was investing in new hand-shaped sterile bags.
Mr Robertson was badly burned after accidentally spilling lighter fluid on his hand close to a naked flame.
He was taken to the University Hospital of Wales, Cardiff, Wales' largest hospital.
Nursing staff coated his injury with a soothing jelly then wrapped it in the plastic bag which also had the words "contents" and "date" stamped on it.
Mr Robertson asked: "Is this what the NHS has come to?
He added: "I know there are government cuts but wrapping patients in Tesco freezer bags is not acceptable.
"You would expected proper burns bag which are sterilised and made for different limbs."
Mr Robertson said he questioned hospital nurses about the freezer bag taped to his hand.
He said: "They backed me up. They told me: 'Something needs to be said. You can't have patients walking out in Tesco bags.'
"They were not angry with me and certainly didn't treat me any differently.
"They were fine, very professional. It's the fact they had to resort to this."
The University Hospital of Wales was investigating why the bag had been used.
A spokesman said: "It is a bag that's sterilised."
Kesh Baboolal, director of acute university hospital services for Cardiff and Vale University Health Board, said: "The accident and emergency unit uses sterilised plastic bags to help protect properly treated and bandaged injuries where appropriate.
"Any medical and surgical equipment including dressings are stored, and where necessary sterilised, and safe for use.
"The health board is investing in new hand-shaped sterile bags and phasing out the current supply."