Waitrose has urgently recalled packs of its own-brand cupcakes over fears they may contain undeclared walnuts.
The supermarket slapped a 'do not eat' alert on its chocolate mini cupcake nine-pack.
Food safety watchdogs warned the product, which costs £2.60, poses a 'possible health risk for anyone with an allergy to walnuts'.
An allergic attack from walnuts usually triggers relatively minor symptoms including cramps, nausea, and diarrhoea.
But in rare cases it can cause anaphylaxis — a life threatening allergic reaction that can kill in minutes by causing the throat to swell up and block the flow of air.
The alert only impacts the nine-pack product with best before dates of July 20.
Waitrose said a 'packaging error' meant some packs contain mistakenly contain a coffee and walnut cupcake.
Point of sale notices, which explain to customers why the product is being recalled, will also be displayed in all stores selling the product, the FSA said.
It added: 'If you have bought any of the above product and have an allergy to walnuts, do not eat it.
'Instead, return it to the store from where it was bought for a full refund.'
A Waitrose spokesperson added: 'We're recalling this product as a precaution, due to the presence of undisclosed walnuts.
'This is because the wrong cupcakes were mistakenly put in the packing.
'We're sorry for the inconvenience and will be offering customers a full refund.'
There are currently no cures for walnut allergies, which affect around one in 200 adults and one in 50 children in the UK.
Tree nut allergies are among the most common food allergies, according to the NHS.
Tree nuts includes, walnuts, almonds, hazelnuts, pecans, cashews, pistachios and Brazil nuts and cause those that are allergic to feel sick, dizzy and get itchy skin.
A rash, swelling or vomiting are among other mild symptoms.
On rare occasions symptoms may be delayed for a few hours after exposure.
Sufferers are told to carry EpiPens or other life-saving auto-injectors in case they are struck down with a reaction.
In severe cases reactions can cause anaphylactic shock — a deadly immune system overreaction that can kill within minutes.
Anaphylaxis, a dangerous inflammation of the airways, can make it hard and even impossible to breath and can cause the heart to stop from a lack of oxygen.
Children with allergies are considered to be especially at risk from severe reactions as, due to their smaller body size, even small amounts of allergens provoke bigger reactions.
Allergies are also often discovered in childhood meaning parents may not have an emergency injection to hand if an allergic reaction occurs.
