butterflytrans

Well, there are four types of immunologically mediated hypersensitivity reactions in the body.

Type 1 - mediated by IgE and the subsequent release of lots of histamine from mast cells

Type 2 - Antibodies attaching themselves to certain sites in the body causing an immune attack (i.e. rheumatoid arthritis)

Type 3 - Antibody:Antigen complexes depositing somewhere in the body causing an immune reaction (i.e. lupus nephritis)

Type 4 - Cell mediated reaction caused by sensitation of the body to an irritant (i.e. rash from hairspray, or from detergents etc. etc.)

A true allergy is the Type 1 reaction that I explained above. It happens when you get a certain allergen in the body (such as cat dander, pollen, dust) which has certain proteins, which when presented to the immune system, attach to mast cells, cause them to release histamine and kazaam, you have an allergic response. If this happens in your upper respiratory tract, you can get runny nose, sneezing, itchy eyes etc. etc. If it happens in the skin, you can get hives and what not; however, if you get a massive release of histamine (say with a person with a severe peanut allergy) you get things like swelling of tissues (angioedema) which can close off your airway which is obviously life threatening.

The above can only happen with proteins, or certain molecules which attach to proteins which then attach to mast cells (penicillin being an example). If you are having a reaction to alcohol, it's is a direct toxic effect of the alcohol, and not an allergy.