Registered nurse Cindy Munro told the Supreme Court she treated Patterson when she was admitted to Leongatha Hospital, in Victoria's southeast, on the morning of July 31, 2023.
Her former in-laws Don and Gail Patterson, and Gail's sister Heather and her husband Ian Wilkinson, were already in hospital after eating the poisoned beef Wellington at Erin's home on July 29.
Don, Gail and Heather all died in the days after the lunch, while Ian survived.
Patterson was charged with three counts of murder and one count of attempted murder but has pleaded not guilty to all charges and is on trial in Morwell.
Ms Munro told the jury she assessed Patterson about noon on July 31 after being involved in the treatment of Ian and Heather earlier that morning.
Patterson reported having nausea and diarrhoea but the nurse said her appearance was different from the other lunch guests.
"She didn't look unwell like Heather and Ian," Ms Munro told the court.
"I recall Ian being so unwell he could barely lift his head off the pillow ... but Erin was sitting up in the bed, in the trolley, and she didn't look unwell to me."
The nurse said Patterson tried to refuse IV fluids and a recommended liver medication but ultimately complied after medical staff insisted.
Patterson also advised Ms Munro that her children had eaten the lunch leftovers the next day but she had scraped off the mushrooms.
Ms Munro told Patterson the children should also come to hospital for assessment but she tried to object, saying she was worried it would stress them out.
"That's when she became quite teary and quite worried," Ms Munro told the jury.
"I did say to her even if she had scraped off mushrooms some could have seeped into the meat and they could be exposed."
Ms Munro organised for an ambulance to transport Patterson to Monash Hospital, where her children were also being taken by her estranged husband Simon Patterson.
Simon's sister-in-law Tanya Patterson told the jury that she visited Erin at Monash Hospital on August 1.
Ms Patterson said she was in the room when a toxicologist confirmed Erin's blood test results were clear and she was well enough to be discharged from hospital.
A police officer who retrieved a leftover beef Wellington sample from Patterson's home on the morning of July 31 also gave evidence on Thursday.
Senior Constable Adrian Martinez-Villalobis told the jury Patterson had provided the passcode for the property's gate and specific instructions on where the leftovers should be.
The beef Wellington remains were located in a brown paper Woolworths bag in an outdoor waste bin where Patterson had suggested, the senior constable said.
The officer agreed Patterson had been co-operative with police throughout their search.
The trial continues.
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