From what I understand it's something you get online. Do NOT use yorkallergyusa.com. They took my money and didn't send the test, and I'm now going through the Better Business Bureau (where the company received an F) and my credit card company to get the $379 back. The York Allergy test in England is supposed to be very credible and endorsed by their Allergists Association over there and everything. I think their test is about $500 in US dollars. It's controversial that the IgG actually shows a response to a food. But there are many people who've taken the test and said it's very accurate. There was just an IBS study done with it, where the IBS sufferers avoided the foods they reacted to, and most got better. It looks like in England, it's actually a test that their allergists use, but doctors here think it's a bunch of hooey. I'm saving up my pennies (after I get the refund from the first place) and getting my test from the real York lab.<br>
My understanding is that IgG tests for delayed reactions, as opposed to IgE which shows immediate reactions which are considered "true allergy." An IgG response is considered more of an "intolerance" than an allergy.<br><br>
Doctors can order IgE and IgG testing. My allergist does both. There are also places you can order the testing online, as mentioned above.