"Unfortunately after Christmas we find a lot of cases of gastro bugs," Dr Lim, a GP in Mt Druitt, said.

"There really is no treatment for it. The best thing is to avoid it."

And avoiding it, Dr Lim says, is fairly simple.

"All food poisoning bugs are all transmitted the same way - poorly cooked or stored food."

One of the notorious causes of food poisoning is salmonella, a bacteria found mostly in animals.

Salmonella infections result in salmonellosis which can cause serious discomfort, including symptoms ranging from fevers and headaches, to diarrhoea and vomiting.

Symptoms start between six and 72 hours after eating contaminated food and can last up to seven days.

As summer heats up and temperatures rise, cases of salmonellosis are expected to jump. There is typically a rise in cases in December ahead of a peak in January, before a sharp fall in April as winter and cooler temperatures arrive.

Salmonella bacteria thrives in the temperature “danger zone”, between five and 60 degrees, while the optimum temperature for salmonella to grow is 37 degrees, according to Food Standards Australia New Zealand.

That means food that might safely be left on the bench for a few hours during winter doesn’t survive the summer heat as the bacteria spreads faster.

NSW Health director of communicable diseases Vicky Sheppeard said leftover food should be stored as soon as possible.

“The longer food is left out the more the bacteria will multiply,” Dr Sheppeard said.

In the worst cases, salmonellosis can be more than just an upset stomach.

"We’ve seen people end up in hospital on a drip," Dr Lim said.

What's more, it's often "young babies, the elderly and those with weakened immune systems" who are hit the hardest, according to Dr Sheppeard.

A quarter of all cases of salmonellosis in the past two years affected children under five.

While NSW Health figures show diagnoses of salmonellosis have been gradually falling over the past few years, Dr Lim warns against complacency.

"We all tend to underestimate how quickly bacteria can grow in food when it’s been left out for any period of time."

To avoid spending Boxing Day in bed, it's best to stash the leftovers in the fridge.

"Don’t leave it sitting out. Have it refrigerated as soon as you can, especially on hot days, to avoid food spoilage."

In the spirit of keeping Christmas joyful, Dr Sheppeard agrees.

"It’s a good rule of thumb that if food requiring temperature control has been sitting on your table for more than two hours, you should throw it out."

Risky food this Christmas: 

• Raw or poorly cooked meat
• Ham, turkey and sausages
• Seafood
• Cream and dairy products
• Potato salad