How are food allergies diagnosed?


There are several ways your GP can have you assessed for a food allergy. Ranging from changing your diet to biposys.

But firstly they will ask you a million questions!

Please be honest

There is no point seeking out support if you will not honestly discuss your concerns. As registered nurses we have heard a million stories but we haven’t heard yours.

We understand as health care providers that certain aspects maynot be pleasant to talk about, maybe embarrassing and might be the first time you’ve discussed this with anyone.

But please don’t hold any information back even if you feel it’s irrelevant, it isn’t. The more you health care provider knows the better we can help you.

Food exclusion and reintroduction:

This test is the stopping and restarting of particular foods and/or food groups to test for reduction of symptoms on stopping and a reaction on reintroduction.

I was asked to complete this test when I was having issues with dairy products. I stopped all dairy for a few months then slowly reintroduced dairy back into my diet and awaited the reactions.

Unfortunately they arrived. Lactose intolerance was diagnosed.

The doctor will ask you to keep a food diary so you can track what youve eaten and any reactions noted. This testing method is a simple one, it can just be a bit annoying rearranging your diet but its really good at gaining results quickly.

The skin pricks

This test comprises of a diluted patch of a suspected allergen being placed onto your skin to see if your have a allergic reaction. This maybe one patch or several if a culprit has not been whittled down.

This test again can be quick regarding results, most people skin will react quickly if an allergen is placed on it.

Blood test

Many doctors on first visiting them will send you for a full blood screen. Particular if they suspect you may have coeliac disease. For coeliacs they are looking for the antibodies that your body will make when responding to gluten.

However, you can have a negative result but still have coeliacs disease. This maybe due to you not have consumed gluten prior to your test. People may also not show the expected coeliacs antibodies on their blood test if the have a condition called total immunoglobulin deficiency. Your doctor may test you for this if you are showing signs of coeliac disease but have a negative blood test.

I have had a negative result for coeliacs so was offer a biopsy test.

Biopsy and internal investigations

If you have had the previous tests completed and still no results your doctor may suggest some biopsies to be completed, these will normally be a gastroscopy or possibly a colonoscopy.

A gastroscopy is where a small flexible tube is placed down your esophagus into your stomach and then into the first part of your small intestines. This flexible tube has a camera and light on the end so the doctor can investigate. The doctor may also take some biopsies from the areas they are investigation to test for signs of allergic reaction. You will be offered numbing spray and a sedative if you wish. The procedure takes around 15 minutes, it can be uncomfortable but normally to painful. As in all invasive treatments there are risk associated which can tearing of the lining of the esophagus which can lead to bleeding and reactions to the sedative, but these are rare.

A colonoscopy is where a small flexible tube is placed into your bottom; air is then pumped in to expand the area of investigation. The doctor will then investigate the area and may remove some biopsy samples for investigation. This procedure can be uncomfortable but normally not painful. You will be offered painkillers and a sedative if you wish. Afterwards you may pass gas from the air that was placed inside you. As in all invasive treatments there are risk associated including which can be tearing to the small bowel, bleeding afterwards and reactions to the sedative but these are rare.

For both these procedures you will need to follow strict dietary advice before hand, you will receive letters with this information on. These diet changes are very important to receive the best results from the test. You should not drive for 24 hours after any sedative so get someone to come with you and drive you if you can.

Alternative tests

There are several alternative tests available to help diagnose food allergies including:

  • Vega testing- where you are tested for changes in your magnetic field in regards to potential allergies
  • Hair analysis- testing your hairs energy fields for changes regarding potential food allergies
  • Kinesiology testing- studying your muscle response relating to potential food allergies
  • Leukocytotoxic blood tests- testing your blood to see if your white cells swell when reacting to allergens
  • Pulse test- Your pulse is taken before and 15 minutes after you have eaten your potential food allergen and if it raises by 10 beats per minute it may show a food sensitivity


If you have any concerns or worries about possibly having a food allergy please contact your registered GP as soon as you can.

Please see the disclaimer policy for further details. 


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