Bluebell Wooi, 26, was wearing her own reusable face covering when she went to board the service from Calabria, Italy back to the UK.
However, crew informed her that she would not be able to fly unless she wore a surgical mask.
Ms Wooi claims she was told by Ryanair staff to ask if any other passengers had a spare disposable mask she could borrow.
A fellow passenger offered her one but it turned out they had already used it, and it was “dirty”, alleges Ms Wooi.
However, she claims she was told to wear it anyway over her own mask, despite having explained to flight attendants that it was not sanitary, reports The Sun.
“It was dirty and I really didn’t want to,” she said. “I just think it’s completely bonkers. It doesn’t make any sense to wear a mask used by a stranger over my own reusable one.”
Ms Wooi added that she was even more perplexed after seeing that cabin crew were all wearing reusable masks themselves.
Travellers have been required to wear surgical face masks on flights to, from and within Italy since 7 August.
Ryanair has a page on its website outlining which masks are appropriate surgical, KN95 and FFP2 and which are not ventilated or fabric.
“Some countries require passengers to wear surgical face masks at the airport and on-board the aircraft,” says the airline.
“It is each passenger’s responsibility to check local requirements before travelling. If you are travelling to, from or within Italy this must be a surgical face mask or you may be denied boarding.”
Alitalia goes a step further, demanding that passengers replace their disposable mask with a new one every four hours and that they “bring an adequate number of protective masks according to the duration of your flight.”