Shahida Shahid, 18, from Worsley, Salford collapsed after eating at Almost Famous in Manchester on 9 January 2015.
She had a dairy allergy but was not told the burger was marinated in buttermilk, and it wasn’t stated on the menu.
Shahid collapsed and was taken to hospital within an hour of leaving the restaurant, but died three days later after suffering a cardiac arrest.
According to the Manchester Evening News, the jury’s foreman said an allergen booklet had not been offered to her as per company policy.
He added that though a ticket specifying Shahid’s allergies went through to the kitchen, they were overlooked ‘numerous times during the preparation, construction and delivery of the burger’.
The jury returned a verdict of misadventure following a seven-day inquest at Manchester Crown Court.
Since the introduction of the EU Food Information for Consumers Regulation in 2014 all foodservice businesses have been required to list 14 allergens including nuts, gluten and mustard on menus, or have their presence communicated by staff.
In 2016 restaurant owner Mohammed Zaman was jailed for six years for manslaughter after the death of a customer with a peanut allergy in what was thought to be the first case of its kind.
The Food Standards Agency says an average of ten people die every year and around 5,000 are hospitalised due to allergic reactions.
Speaking at the conclusion of the inquest Shahid’s brother Rasel told the Manchester Evening News he hoped the incident would prompt other restaurants to be more aware of customer allergies.