"My three-year-old had a sudden allergic reaction to fish after eating it all her life."

It was an ordinary Sunday evening. My then three-year-old daughter was eating fish and veggies for dinner. Unlike many kids, she loved fish and ate it at least once a week. It was our go-to meal.

But this time, something different happened. She started itching a little lump on her hand which we initially thought was an itchy bite. Soon, the lumps started spreading up her arms, trunk and suddenly her lips and eyes were swollen.

“Maybe it’s an allergic reaction?” I asked my husband, then called Healthdirect to check. The nurse went through her symptoms and quickly worked out that it was an allergic reaction.

I wasn’t that worried, but then the nurse asked: “Is she complaining about having an itchy throat?” My three-year-old said yes, her throat was itchy and her tongue hurt.

That’s when things got serious. The nurse connected me with 000 and before I knew it, an ambulance was on its way. I remember watching my daughter’s puffy, petrified face and willing her airway to stay open so she could keep breathing.

I had done a CPR course before she was born and I was running through the steps in my head. Waiting to hear those sirens was the longest 10 minutes of my life.

But we were so so lucky. By the time the ambulance arrived, her reaction had subsided, and she didn’t need any adrenaline. The ambulance officers didn’t waste any time though. They took us straight to hospital where she was given an antihistamine and monitored for a few hours.

It took a few months of blood and prick tests but we found out that my daughter has an allergy to some fish. I was shocked – I had always thought you’d find out that your child had an allergy when they’re trying new foods as an infant.

Watch: These are the signs and symptoms of an allergic reaction.

When do allergies show up in children?

It turns out that although it’s rare, allergies can occur at any age.

According to CEO of Allergy and Anaphylaxis Australia, Maria Said, most people who are going to react do so on their second exposure of that food.

“However, there are reports of adults who have eaten peanuts or prawns all their life, suddenly having a reaction,” Said said.

My first question was why? But like a lot of questions about allergies, there are no clear answers.

“We have no idea why it happens.”

There are theories like the hygiene hypothesis and lots of research into probiotics and gut flora. There is also a push for us to introduce allergenic foods earlier rather than later.

The LEAP study in the UK has found that high risk infants who ate egg and peanut butter before the age of one were much less likely to develop an egg or peanut allergy. Some babies still did develop an allergy but most did not.

How can we avoid reactions in our allergic kids?

One of the worst things about having a child with an allergy is anxiety about what she eats when I’m not there. Everyone at pre-school and childcare knows and I always keep an eye out for fish products at birthday parties.

I try my best, but I’m not perfect. Just last week, she ate a fish finger that she thought was a chicken nugget. I had my EpiPen on hand but luckily the fish was one of her non-allergic ones and she had no reaction.

Said said it’s important to have an emergency plan in place because mistakes do happen.

“This is one of those situations when knowledge is power, you need to have your strategies in place,” she said.

Every time you buy something, you should check the pack to ensure ingredients haven’t been added since the last time you bought it.

You can also sign up as a free member of Allergy and Anaphylaxis Australia and get their food alert newsletter.

How to help families with food allergies.

What if your child doesn't have an allergy? Are there any precautions you can take? Should we avoid giving our kids nuts at a public park?

Said said allergies are a community concern and we all have a role to play but it’s also about finding the balance. For instance, if our kids are likely to smear their food over play equipment that other kids might touch then think about what they're eating.

Do we need to give our kids a peanut butter sandwich that day? Maybe Vegemite might be more appropriate. On the flip side though, Said highlighted that parents of allergic kids need to be realistic.

“It’s highly unlikely that a child is going to go into anaphylaxis from sitting on a bench that another child has eaten a peanut butter sandwich on three hours before,” she said.

What are the symptoms of food allergies?

The signs of a mild to moderate reaction include:

• Swelling of the lips, face, eyes,
• A tingling mouth,
• Hives and welts anywhere on the body,
• Abdominal pain, vomiting (this can also be a sign of anaphylaxis for insect allergy).

The signs of a severe anaphylaxis allergy include:

• Swelling of the tongue, difficulty talking/hoarse voice,
• Swelling/tightness in the throat,
• Difficult/noisy breathing, wheeze or persistent cough,
• Persistent dizziness or collapsing,
• Young children may go pale and floppy.

I find it really reassuring when my friends tell me they know how to use an EpiPen. There are some great videos that show you how such as those on the Allergy Facts website.

As for us, a year and a half on, we are still pretty confused as to what my daughter is and isn’t allergic to. We carry an EpiPen and have an anaphylaxis action plan.

We still eat lots of her ‘non-allergic fish’ such as tuna, anchovies, mackerel and swordfish but we need to be careful they are not contaminated by other fish when we buy them. Many people with fish allergy do not eat any fish but we have made the choice to eat the fish that we know she can tolerate.

I’ve learnt that allergies are confusing and sometimes they seem quite random. They’re also incredibly serious and we all need to play a part in helping our friends and family with allergies live normal and happy lives.

Does your child have a food allergy? How do you manage it? Tell us in the comments section below.

Caitlin Wright is a freelance journalist, SEO website copywriter and mum of two gorgeous girls. Read more of her writing here.