To go back to GP for allergy after negative blood test.

[whackamoley]

So I had a bad reaction to eating prawns, felt really sick, throat felt really weird and my voice went hoarse and I threw up quite badly, I took some piriton which seemed to calm everything down.

Gp referred me to the allergy clinic, they did a blood test which came back with no sign of allergy.
Okay, all fine.

A few months later I was at a party and they had various canapés one being prawn. Up until now I had been avoiding them but in my head I knew I had had the blood test result back so I ate one. Immediately my lips started to tingle, I managed to get to a pharmacy within 5 minutes and took some piriton and felt much better. Around 2 hours later I started to feel really ill again, almost weak like I couldn't stand, then I violently threw up.

Would it be unreasonable to go back for further tests? Could the blood test show no allergy even though there is one?

I'm obviously avoiding prawns now, but I am really scared of cross contamination or accidentally consuming them in something.

I dont think you need further allergy testing. Skin prick test is all you woukd get and you already very clearly know the answer. What more are you hoping to get from it?!!

Avoid it!

You can but there may not be a lot else they can do. Just assume you are allergic to prawns and act accordingly.

As I said I am avoiding prawns now. I am worried if I have them unknowingly and the reaction may get worse. What if I need an epipen?

You could just carry piriton, as that appears to work. You haven't had a reaction that requires an epipen. Prawns are one of those things that you're unlikely to find in other things like you might dairy or soya or nuts. It's unlikely prawns would be in anything non-seafood related, so you can just check.

Maybe ask for a copy of the blood test results the allergy clinic took so you can see exactly what allergies you were tested for. It may be something you are eating along with the prawns that you are having a reaction to?

You may find this interesting. Although mainly about intolerance, it also discusses food allergies too.
podcast

Bloods are not diagnostic for allergies, it is common to get false positives and false negatives.

But you know what you're allergic to now.

You need to carry AHs.

You'd be very unlikely to get epipens without previous anaphylaxis.

Read up on crustacean allergies so you know what to avoid.

Read labels and check ingredients when you're eating out.

To correct myself:

*Bloods are not typically definitive for identifying allergens.