A 13-year-old girl with a severe dairy allergy may have been served hot chocolate made with cow’s milk after a possible “miscommunication” of the order, an inquest heard on Tuesday.

Hannah Jacobs, who had been allergic to dairy products along with fish and eggs since she was a toddler, died within hours of taking one sip of the drink, east London coroner’s court was told.

Urmi Akter took the order for the takeaway drinks on 8 February 2022 from Hannah’s mother, Abimbola Duyile.

Akter used her legal right, under coroners’ rules, not to answer a series of questions that could be seen as incriminating as she gave evidence at the inquest on Tuesday. They related to her training, understanding, knowledge and actions as she was being given the order.

The court has been told that Hannah suffered an “immediate reaction” after one sip of the takeaway drink that her mother bought before attending a dental appointment at 11am. Hannah, of Barking, east London, was declared dead by 1pm that day.

A postmortem examination found the teenager died after experiencing a hypersensitive anaphylactic reaction triggered by an ingredient in her hot chocolate that caused an allergic response.

The inquest has heard there is a factual dispute about the order and Duyile says she asked for two soya hot chocolates and asked staff to thoroughly clean the equipment.

Akter, who had worked at the Costa Coffee franchise in Barking for about eight months, told the court she could hear and see Duyile “clearly” as she served her at the counter.

In her statement to the inquest, she said Duyile asked for two hot chocolates before adding: “Can you wash the jug because my daughter has a dairy allergy?”

Under Costa’s rules, customers who ask for a non-dairy product or state they have a dietary requirement should be shown a book that is kept under the till that includes ingredients and details of how the drink is made, the court heard.

Akter’s statement said: “I did not show the mother the book as she told me washing the jug was fine. I thought she, as the mother, would know more about [it]. I gave her the drink she requested.”

Akter told the court she had repeated Duyile’s request that the jug be washed and also pointed out that hot chocolate is made from milk. She said Duyile replied: “That’s fine.”

The assistant coroner Dr Shirley Radcliffe said: “As far as I understand, you said the mother mentioned the dairy allergy. The book was not shown to the mother and the only thing done was to make one drink, wash the jug and make the other drink.”

The coroner also asked Akter why she had not shown an allergy book to Hannah’s mother in accordance with her training and if she thought it was “strange” that the customer asked her to wash out the jug between making the two drinks.

Akter, who sat beside a Bengali interpreter as she gave evidence, declined to answer.

Emily Slocombe, representing Hannah’s family, asked: “If you had got out the allergy book and shown and discussed this with Hannah’s mother, this would have been an opportunity for any miscommunications to be cleared up, wouldn’t it?”

Slocombe also asked Akter if she had repeated the order back to Duyile and queried why she did not confirm whether cows’ milk was being used and if she had told the barista who went on to make the drink about the allergy.

Akter did not give an answer to these questions.

The inquest continues.