There are 2 terms out there that could use a little clarification.
Sensitivity, vs Allergy.
There are several types of immune reactions. I’m only going to address 3. IgE, IgG, and IgA.
IgE is what your doctor thinks an allergy is. It is an immediate and strong reaction to a food or other stimulus. Think hives, stomach cramps, wheezing, or the worst of all, anaphylaxis. This is what most allergy tests are actually testing for.
IgG reactions take longer to show up. The reactions can be severe or much more subtle. Many food problems are actually this kind of reaction.
IgA is another slow reaction and is often linked to leaky gut. It causes bizarre reactions to seemingly unconnected things. Like asthma in reaction to dairy foods 2 days later.
If you are talking to a physician the word ‘allergy’ is reserved for IgE. This is also the reason there have recently been a lot of news articles about how allergies are much more uncommon than people would like to believe. They are using a very clinical and narrow definition of ‘allergy’.
If you have an IgG or IgA reaction to something, then technically you have a ‘sensitivity’. Unfortunately, there is a strong public feeling that a ‘sensitivity’ probably isn’t really the problem that an ‘allergy’ is, and you’re probably just making a fuss about nothing. It is true that these, to the best of my ability to research, do not cause anaphylaxis, but hives are hives and vomiting is vomiting and it doesn’t really matter what caused them, you’re miserable either way.
So if you are speaking to a physician or other scientific professional, by all means, use the terms according to their definitions. If you are speaking to a food service professional (read waitstaff) I highly recommend using the more idiomatically appropriate term ‘allergy’ because they are much more likely to take you seriously and you are less likely to wind up with the aforementioned hives.