Macheras said she had just settled into bed when she heard her son's screams.
"When I got to him, he was throwing his clothes off, screaming that he was on fire," she said.
"He jumped into a cold shower immediately and I called an ambulance, but he just kept yelling that he was on fire.
"The pain was so bad that he just couldn't take the burn away from the cold water."
Her son was taken to The Alfred hospital with second- and third-degree burns across his abdomen, chest and hands, and underwent painful surgery for a skin graft earlier this week.
Alfred Health burns surgeon Dane Holden said it was a horror situation that played out each year.
"Every winter we get a spike in hot water bottle burns, which is a trend we really want to see reversed because they're entirely preventable," he said.
"A few safety precautions, such as never filling your hot water bottle with boiling water, hanging it up to dry before reusing it and replacing it every 12 months will go a long way to avoiding putting yourself in danger."