For anyone with food allergies, food challenges of various kinds will likely be an important part of gathering critical information for you, since allergen skin testing and blood IgE tests have limitations
Sometimes a food challenge may be recommended early on in the process in order to help determine which foods you need to begin avoiding or need to continue to avoid, and which you do not. After some time on your SLIT allergy drops treatment, it is likely that your immune system has made changes somewhere on the spectrum between desensitization and true tolerance, and as such has gained the ability to tolerate some amount of your food allergen(s). Since there is unfortunately no way to confirm this with a blood IgE level or a skin test, a food challenge test would be necessary to get the best possible information. Your allergist will discuss with you when and why certain food challenges are recommended.
There is always a degree of risk to a food challenge, so it is important to weigh out the risks and benefits to determine whether or not it is appropriate and important to undertake a food challenge at that time
Any type of allergen challenge test runs the risk of causing an allergic reaction. Since food challenges involve eating a possibly allergenic food, this risk is a bit higher in general than applying the food allergen to the skin (a skin food challenge) or an allergen skin test. Reactions to a food challenge can be minor and non-allergic (such as not liking the taste of the food you have been avoiding for a long time), can be minor and allergic (like becoming itchy, congested, sneezing, or having a few localized hives), can be moderate and allergic (like having a clear stomach ache, vomiting once, wheezing, or having a larger amount of localized hives), and rarely can be severe and allergic, including anaphylaxis. The risk of anaphylaxis is lower when a thorough risk assessment is performed during the process of deciding whether or not a food challenge is warranted, and also when a GOFC protocol is used rather than a straight OFC. Low and sometimes moderate-risk food challenges may be appropriate for a private clinic setting in certain situations. However, some moderate and certainly any high-risk food challenges needed for some important reason should be undertaken in a hospital setting overseen by an allergist there, just like drug allergen desensitization procedures.
There are many benefits to undergoing a food challenge at the right time. Challenging your immune system with a food of concern can give you a real-life example of how your immune system and allergy cells handle the exposure. It can also help you work through any anxiety you may feel about the food, since doing it under medical supervision will help put you initially more at ease, and the sense of accomplishment afterward and new familiarity with food can help make coming across the food out in the “real world” much less scary. When a food challenge goes well, the knowledge gained from it is often life-changing in a great way, opening the door to many new personal and social opportunities.
A graded oral food challenge (GOFC) provides some nice safety measures to add an additional layer of protection into the process
A large amount of food is not consumed at once in a GOFC. Instead, it is ingested in carefully planned and timed stages. Because of this, it is possible to observe for early signs or symptoms of an allergic reaction starting, and then minimize further exposure to the food allergen in order to not further overwhelm the immune system which could push the reaction much farther.
The results of a food challenge are not as clear cut as a strict “pass” or “fail” and can provide information that opens doors for you
A straight oral food challenge (OFC) – in which a large amount of the allergenic food is consumed at once – ends up providing a pass or fail type of result reported in the end. Either you appeared to tolerate eating the food, or you had an allergic reaction and did not. However, even if you “fail” an OFC, the test can provide additional valuable information to you and your allergist about how the severity of reaction compared with any previous reactions and if improvement appears to have been made. With a GOFC, we have safer, better, and even more opportunities to learn how much of your allergenic food you can tolerate. If you are able to tolerate a certain amount of a food that you previously could not tolerate at all, whether or not you made it to eating the full food challenge serving, that achievement is a huge success and provides both you and your allergist with lots of extremely valuable information about your immune system for future planning.