Anaphylaxis but negative prick test?

[KarmaCaramello]

Hi, 13mo dd has had three anaphylactic reactions to different foods while weaning. But when we went in for allergy testing it all came back negative. They even did a blood test to check.

We’re getting an appointment for a food challenge but I’m so confused? The doctor said maybe she just had a virus instead of allergic reaction but definitely not - one bite and instant projectile vomiting, hives, and swelling that resolved with an epi pen.

Has anyone else had experience of this?

[Runninghappy]

She may be too young? My daughter had RAST tests when she was 11 months old as they said skin prick tests weren’t accurate with babies - and said the RAST test may also give a false negative (it didn’t) I can’t remember how old she was when she did have skin prick tests, as she’s 15 now, but perhaps they’ll repeat them in 6 months time? Sadly my daughter still has anaphylaxis to milk now at 15 years so I hope your baby grows out of it.

[sarahc336]

Well dd2 has a peanut allergy and this came up positive on her skin prick test but she's allergic to humours but the main ingredients on the skin test all came back negative so yes it seems they can present as having an allergic reaction but it doesn't show as positive on the skin prick test. The hospital told me humours was fine but we choose to avoid it as we've seen her face after eating it

[KarmaCaramello]

Interesting thank you…maybe we should ask to wait until we repeat the allergy test next year before doing the food challenge. I don’t want her to suffer another reaction for no reason :(

[Alloveragain3]

Frustratingly you can get both false positives and false negatives with allergy tests.

"Reaction trumos testing", meaning if she's had a clear allergic reaction then you can rely on this over any test result.

[Alloveragain3]

*trumps

[Superscientist]

A negative result in kids means can be a false negative.

Unlikely to be the case here but I have non-immune anaphylaxis which are triggered not by an allergen but by my body over reacting to histamine in food. Sometimes called a histamine intolerance or a histamine release reaction. I have negative skin prick tests and blood tests. There is no consistency in the triggers either as it depends on the total histamine content I have had for that day

The most valuable diagnostic test in food allergies is a food diary that says they eat this and x happens. We did it again and the same happened. We removed the food and X stopped happening