Probably the most common allergy test is the skin prick test. The way it works is that a drop of liquid (allergen solution) is dropped on the skin and a small scratch is made through the liquid. This allows the suspect allergen to enter the body and interact with the immune cells just under the skin.
The Skin Prick Test Process Explained
Each drop of liquid contains the elements of a single food in a concentrated form. The allergy tester jots down which allergen extract has been used, so that if there is an allergic reaction occurs they know which compound/food has caused the reaction.
If there is going to be a reaction this normally occurs within 15 minutes. Usually, a small red wheal or lump appears. It can be itchy too. Within 30 minutes, most of these little lumps disappear.
The whole process takes only a minute per allergen being tested. It is almost painless because the mark is just a tiny scratch made with sterile needles.
To make sure that the test is accurate, one or two neutral marks are made. The solution used for these test marks is normally sterile salt water. Even in people with severe allergies, there should be no reaction to this mark.
Normally, there is also a positive reaction control mark made. The compound used for this mark is pure histamine, which is the compound that the body produces when reacting to an allergy. This mark should flare up if the body has a healthy response to allergens. The positive reaction test is there to make sure that the person taking the tests have done as asked and stopped taking anti-histamines 48 hours before the test is due to be conducted. If you do not stop, taking the antihistamines as asked your body’s reaction to anything you are allergic to will be dampened down and the test will prove useless.
Those samples that swell are the food products you are likely to be allergic to. Eliminating them from your diet should stop the symptoms you are experiencing.
How accurate are food intolerance skin prick test results?
However, the problem with using prick testing for food intolerance is that you may have some level of resistance to those compounds, so may not have a huge reaction to the limited sample that is applied to your skin. Those with a full-blown allergy will respond, so this kind of test is far more useful for diagnosing full-blown food allergies.
The other problem with the skin prick test is that there is a relatively high rate of false positives. In other words, a reaction that suggests you are allergic to a food, when in reality you are not actually allergic to that food. Once your body takes the food and puts it through your digestive system sometimes the allergic impact is reduced. Meaning that you can in fact safely eat that food.
For this and a host of other reasons, you should consider undergoing other more effective forms of testing for food intolerance or allergies.