I need a straight answer. what is allergic reaction to insect bites?

What it says.: If you get stung or bitten by an insect, and you are allergic to the insect's venom or saliva, you develop an allergic reaction to the sting or bite. Usually it's just itching, redness, and swelling around the bite, but in rare cases it can evolve into anaphylactic shock which is life-threatening. Antihistamines may help mild cases, but if you have trouble breathing or other symptoms see a doctor.

Allergy: Insect venom is made usually of proteins. Our immune system can develop antibodies to these venom proteins. This reaction will cause certain immune system cells to release things into our system that cause typical allergic symptoms. Histamine is a common such chemical. That is why antihistamines can help in allergic reactions. Beyond that, i'd need a few hours to explain better.