And the crew insisted he pay for the food, passenger Billie Appleton told the Swedish tabloid Aftonbladet.
"We want Ryainair to apologize," she said of the Irish low-cost airline. The family is also considering legal action.
Her stepfather, Per-Erik Jonsson, became ill on a flight back to Stockholm, Sweden, from London and went into cardiac arrest, she said.
Cardiac arrest is when a person's heart fails to contract effectively.
"They said he had low blood pressure and gave him a sandwich and a soda. And they made sure he paid for it," Appleton told the newspaper. Ryanair offers food and drinks for purchase through a "buy on board" program.
Jonsson first broke into a cold sweat and asked his wife for some water, Appleton told the newspaper. He then lost consciousness.
Appleton, a nurse, intervened while Jonsson's wife alerted the flight crew.
"He didn't respond when I tried to shake him. But after I slapped him in the chest, he began breathing again," Appleton said, adding the crew responded only when she shouted for a doctor and said he needed oxygen.
The only other attention the crew gave the family was when it insisted on payment for the food and drink, she told the newspaper.
Ryanair spokesperson Stephen McNamara told the Swedish newspaper The Local the crew handled the situation according to European Union requirements.
"In line with procedures for such cases, a Ryanair cabin crew suggested a diversion to the nearest airport or to have an ambulance on standby on arrival at [Stockholm-Skavsta Airport] so that the passenger could receive medical treatment," he said.
"However, the passenger's companion, who identified herself as a nurse, declined this offer," he said.
Jonsson's family disputed the airline's version of events and said no ambulance was waiting for them when they landed, forcing them to drive Jonsson to the hospital themselves.