"It only took seconds." Sophie Cachia on the moment a family meal made her son go "limp".

It was like watching a “zombie plague” and it took “only seconds”, parenting blogger Sophie Cachia said about watching her son, now aged three, suffer an anaphylactic reaction.

It happened as almost every near-tragedy happens: everything is so simply, blisteringly normal, until it is not.

“It was 2016 and our little family was living in Adelaide,” the now-26-year-old wrote for Wattle Health.

“That day I hadn’t really gotten around to organising anything for dinner, but I was stoked to find a pre-made pasta sauce in our fridge ready to go! I whipped up some ravioli and popped on the pumpkin and walnut sauce.”

Cachia, who created The Young Mummy, said she wondered if her son Bobby had tried walnuts before. She knew he had enjoyed muffins and banana bread with no reaction, that he’d been exposed to peanuts, almonds and pine nuts without problem. She thought walnuts should be fine.

A post shared by Sophie Cachia (@sophiecachia_) on Apr 16, 2017 at 2:16am PDT

His reaction started when a spoonful of sauce landed on his arm but Cachia mistook it for a burn.

“Thinking I was the worst mum ever for allowing my son to burn himself, I quickly cleaned him up and, just as I did, he simultaneously popped a spoonful of sauce in his mouth. No pasta, just sauce,” she wrote.

That’s when things became dangerous, with Bobby’s reaction turning into the “zombie plague” that “only took seconds”.

“His mouth started to bubble and mini-hives appeared before I even had time to say ‘CRAP’,” she wrote. “I could see the hives getting bigger and spreading all over his cheeks, his ears, up the back of his neck and starting to go down his chest. He started to scratch like a dog and cough.”

Panic quickly set in and Cachia first thought to call her mum. She then messaged her husband’s football coach while Jaryd Cachia, who played for the South Australian National Football League at the time, was at training.

Jaryd ran home – he was just down the street – and the pair hopped in the car to race an increasingly irritated Bobby to the emergency room.

“The panic in these situations is so high that we just went, “JUMP IN THE CAR!” because together we thought we could get there quicker. In hindsight, this was a TERRIBLE move,” Cachia wrote for Wattle Health.

“In those 10 seconds of grabbing my bag, with Bobby under my arm, the most horrific thoughts started going through my head: I’m going to kill my son.”

LISTEN: One-in-six people are ACTUALLY gluten free. Post continues below.

The three of them hit traffic and Cachia desperately tried to catch the attention of a police car, which she thought might be able to get them to the hospital faster. She tried speeding. She told Jaryd to take Bobby from his car seat. She knew it was unsafe, but she thought her baby was dying.

“The lump in my throat as I write this is making me feel queasy,” she wrote. “I was a maniac. I was screaming at the top of my lungs for cars to move or for the lights to change, even contemplating getting out and running to the hospital (again, my logic in this situation was not great).”

“My greatest fear started to kick in when the choking, vomiting and crying turned to utter silence. Bobby had gone limp. Jaryd said, ‘C’mon buddy. Wake up’. This is when I vomited on myself driving and let out a scream that I didn’t even know was inside of me. I was a desperate mum who had made a bad decision. ‘This is it’, I thought. ‘I’ve killed my boy’.”

Finally, they reached the emergency room and, though they were told to wait, a nurse who heard Cachia’s screams rushed in to help them. It was an experience, Cachia said, she “wouldn’t wish on her worst enemy”.

A post shared by Sophie Cachia (@sophiecachia_) on Jul 8, 2017 at 10:38pm PDT

Bobby was diagnosed anaphylactic to both walnuts and pecans, and now, the heaviness of his allergies and the fragility of his life hangs over Cachia.

“That whole scenario would have all happened in no more than 15-20 minutes,” Cachia wrote. “If he is to come across walnuts again the reaction will be greater. Perhaps quicker. Perhaps fatal.”

“Luckily for us, we walked out of the hospital that time with a healthy boy and two educated parents.”

Bobby now carries an Epipen, as well as an asthma puffer and Zyrtec drops, wherever he goes.

Sophie and Jaryd also now have a daughter, Florence, born in January last year.

For more information on allergies, click here.