Negative skin-prick tests explained

Skin Prick Test Negative

Skin Prick Test Negative does not mean safe to eat says Dr Rodney Ford

Asks a desperate mum, “I really need help. Your eBook is great, but I can’t figure out why my baby has such severe eczema. Your eClinic didn’t give me any new info and the skin-prick-test came back all negative – but she is scratching her face away please help me!” In my Clinic, I find that the interpretation of  negative skin-prick tests causes the most confusion.

Negative skin-prick tests explained

People think that this is an ‘allergy test” with a yes/no answer to food allergy. Unfortunately, It is not. So, negative skin-prick tests explained: I carry out skin-prick-testing on nearly all of my patients. But these skin-prick-tests can only detect immediate allergy, which is caused by an IgE reaction.  It cannot detect any other sort of adverse food reactivity/intolerance/sensitivity.

Most adverse food reactions have a non-IgE cause. These people have negative skin-prick tests. A trial elimination and challenge of suspected foods is the only sure way to know if that food is causing trouble.

Negative skin-prick tests do not rule out food intolerances

What can a skin-prick-test diagnose?
The purpose of doing skin-prick-tests is to detect any IMMEDIATE allergic reactions (to foods and to inhalant/environmental allergens).If you have a positive skin-prick-test to a food, this means you have developed specific-IgE-antibodies against that specific food. If you eat that food, then it is likely that you will experience an adverse reaction within a few minutes – that is ‘immediately’.

Skin prick test for IgE allergy

Skin prick test for IgE allergy only

What does a negative skin-prick-test mean?
negative skin-prick-test simply means that you have NOT developed any IgE-antibodies against that specific food. A negative test does not mean this food is safe for you to eat. That food could still be causing you an adverse reaction.

Negative skin-prick-tests will occur in these circumstances – if you
1: have not developed any IgE-antibodies to that allergen.
2: are too young (before three months of age) to react in your skin.
3: have a non-IgE food intolerance.
4: have previously had a positive skin-prick-test but have developed tolerance.
5: are on an anti-histamine which will cause a false negative test.
6: have no food reactivity.

Usually skin-prick-tests to foods are negative in people with gut problems (diarrhoea, constipation, reflux, irritable bowel (IBS), bloating, tummy pain); in older children and adults with eczema/dermatitis; in celiac disease and gluten sensitivity; in cow’s milk intolerance.

In summary, a negative skin-prick-test does not rule out the possibility of an adverse food reaction.
Food Puzzles Explained Newsletter explores the many facets of food-related-disorders.

If you would like to read more about solving eczema puzzles, then you might like to look at this ebook: “Eczema: Cure It!” by Dr Rodney Ford.