Havana , Cuba ( CNN ) -- A jellyfish sting has stopped an Australian endurance swimmer , just 11 hours into her attempt to swim from Cuba to Florida . Chloe McCardel was forced to end her journey prematurely `` due to a severe debilitating jellyfish sting , '' a spokesman said in a statement . The swimmer was on a boat heading toward Key West on Wednesday night , spokesman Tim Stackpool said . `` She will spend the next 24 hours recuperating before deciding on her plans going forward , '' he said . Earlier Wednesday , McCardel -- slathered in a thick coat of sunscreen -- lept into the waters off Havana to begin her daunting 100-mile swim across the Florida Straits . Her goal was to set a world record for the longest unassisted swim . Before diving in , McCardel said she expected her marathon swim through shark- and jellyfish-infested waters to take 60 hours . `` I think it will all work out well , '' said McCardel , 28 . `` It will be tough though ; it 's not going to be an easy ride . But we will get through it as a team . '' The attempt cost around $ 150,000 to finance , McCardel said earlier . She said she hoped to raise money for cancer research and try to improve U.S.-Cuba relations . Each stroke the Australian swimmer took was monitored by teammates in two boats escorting her and by scientists at three universities in the United States . But other than liquid meals handed to her in a bottle every half-hour by a kayacker paddling near her , McCardel said she would not receive help during the long-distance swim and not use any swim aids such as flippers or a wet suit . In 1997 , fellow Australian Susie Maroney swam the straits from inside a shark cage . Since then , several high-profile attempts to cross the Florida Straits without a shark cage have been attempted . All have failed . McCardel said she would use `` a shark shield '' device that emits an electromagnetic pulse to keep away hungry predators . But forgoing a full body suit made her more exposed to jellyfish stings . Diana Nyad abandons swim after storm , jellyfish stings . CNN 's Catherine E. Shoichet contributed to this report .
Chloe McCardel will spend 24 hours recuperating , a spokesman says . The actress was hospitalized after suffering an allergic reaction to the medication she took for her migraines and nausea last week in Los Angeles's Cedars-Sinai Medical Center. Her goal had been to set a world record for the longest unassisted swim .