As many as 200 visitors and staff fell ill with the suspected norovirus at the Bognor Regis camp in West Sussex last week as it was packed with 5,000 people.
They complained of symptoms including vomiting, diarrhoea, stomach cramps and high temperatures, prompting Butlins to offer refunds.
Irwin Mitchell solicitors said they are representing an increasing number of people who suffered illness at the resort – with 23 people coming forward so far.
Among those affected was Kathleen Gilmovitch, 43, from Ellesmere Port, Merseyside, who fell ill three days into a week-long break with her family.
She said: “The cramps were so bad that I would literally fall out of bed and crawl to the bathroom because I could not physically walk.”
A spokesman for Butlins said: “The speedy reaction of our management and staff in eradicating the recent outbreak of suspected norovirus received the full approval of health officials from Arun District Council and the Health Protection Agency.”