A section of Adelaide's Lyell McEwin Hospital was cordoned off by police overnight when a man presented at the hospital feeling unwell after being exposed to an unknown substance.
South Australia Police said the patient was approached outside Elizabeth Shopping Centre at about 1:00am by a man who offered him a free ticket.
Shortly after taking the ticket, he became ill and was taken to hospital, where he was presented with burning hands and breathing problems.
Police and Metropolitan Fire Service (MFS) crews responded to the hazardous material incident, an MFS spokesperson told The Huffington Post Australia.
MFS firefighters wearing protective clothing and breathing apparatus tested the patient's belongings and were unable to determine the nature of the hazardous substance.
Hospital staff who dealt with the man reported suffering similar symptoms and were decontaminated by the MFS along with the original patient.
Police confirmed on Tuesday that everyone involved in the incident had recovered and that services at the hospital had returned to normal.
While no threats were made, police have seized items for further forensic analysis.