Doctors are concerned by a rise in West Australians treated in hospital for food poisoning, prompting warnings to avoid leaving food unrefrigerated in the heat.
Nineteen people have been admitted to Royal Perth Hospital's emergency department with gastroenteritis since Boxing Day, which contributed to Thursday being its busiest day on record.
According to the Department of Health a further 11 people presented to hospitals around the metropolitan area on the same day with heat-related illnesses, although only two were admitted.
Perth's heatwave is tipped to continue until New Year's Day, with the Weather Bureau forecasting temperatures of 40C and above for today, tomorrow and Monday.
Royal Perth Hospital emergency physician Kerry Hoggett said it was unclear how many of the gastroenteritis cases were related to food poisoning but most of the patients were young people who required treatment for rehydration and medication for nausea and cramps. "The main thing is that people need to make sure food is either very hot, if it's hot food, or is kept in the fridge," Dr Hoggett said.
"With the heatwave at the moment, certainly it doesn't help, with food going off much more quickly than you would anticipate."
Symptoms of food poisoning typically include abdominal cramps, diarrhoea and vomiting.
Dr Hoggett said the decision about whether to seek hospital attention would depend on an individual's age and the severity of their symptoms.
"Certainly people should come to us if they're at the point where they can't tolerate fluid by mouth," she said. "Abdominal pains, not passing urine or having urine of a very dark colour are all indications of being dehydrated.
"For most people, simple measures are best, so something like rehydration salts from the pharmacy and making sure you keep your fluid intake up would be fine."
State Health co-ordinator Tarun Weeramanthri said people should stay indoors during the heat of the day, use air-conditioning if they had it, drink fluids and avoid consuming excessive alcohol.