A teenager needed hospital treatment after suffering an allergic reaction from eating at a Pret A Manger store in Cardiff, it has emerged.
The 2015 incident was revealed during the inquest into the death of 15-year-old Natasha Ednan-Laperouse this week.
Natasha went into cardiac arrest on a flight after eating a baguette with sesame at Heathrow Airport in 2016.
Pret A Manger said they were “very sorry for this customer’s experience” in a statement.
The inquest found the food chain’s labelling was “inadequate” and heard of other cases including one in Cardiff.
The hearing at West London Coroner’s Court was told the Cardiff case was one of nine in the UK where someone had suffered an allergic reaction after eating Pret products containing sesame baked into the bread.
The incident in October 2015 involving the 17-year-old customer was described as “life-threatening”.
She was treated immediately by her doctor father and was taken to hospital where she received intravenous medication.
The mother, also a doctor, called Pret a Manager to tell them about the incident, but the inquest heard it had taken more than a year for the sandwich chain to improve its labelling policy.
Trading standards officers inspected the premises in Cardiff following the incident.
In a statement, Pret A Manger said: “We are very sorry for this customer’s experience, and we would like to invite her and her family to get back in touch so we can give them the apology they deserve.
“We have made improvements to the way we provide allergen information, and we know there is more to do.”
A Cardiff council spokesman said: “The inspection found that the company was compliant with the legislation, as notices were printed and put up in the store that people with food allergies should contact a member of staff.
“Information on allergens was also printed and made available for the public to see.”
Under current food regulations non pre-packaged fresh food made on the premises does not need to be individually labelled with allergen or ingredient information.
Another allergy sufferer has told the BBC’s Victoria Derbyshire programme about her experience at a Pret a Manger.
Former Cardiff University student Lucy Sherriff said she became ill when she ate a salad containing pistachios.
She said: “I was very lucky that I didn’t go into anaphylactic shock. I think if it had been peanuts it would have been a different story.”
She said had not received an apology from the store in question, so complained to head office, which offered her a £5 gift voucher.
“You end up basically having to play Russian roulette with your life, which in this day and age is not acceptable,” she said.