What is causing an allergic reaction?

What kind of deadly allergic reaction is this?

• i heard on the scanner that there was a kid who could barely breathe and was beginning to lose consciousness and he was laying on the ground or something somewhat responsive but getting to a bad state. i heard a few minutes later wen the paramedics were there, he had some kkind of allergic reaction and they didnt know what it was yet. they hooked her up to a bunch of stuff i guess and brought her to the hospital by ambulance. what kind of allergic reaction could that be? how do they determine what the allergic reaction is? how do they treat and make it so the person doesnt die?

• Answer:

  From what you're saying, I'm pretty sure it's anaphylactic shock. Long story short, it's basically a severe allergic reaction. His throat is constricted and his blood vessel are larger than normal (dilated); in other words, his body isn't getting enough oxygen. It's pretty bad. Leads to coma, brain damage, and eventual death if he doesn't get medical attention. Any form of allergy can cause it; it's just the severity of the allergic reaction. Allergic reactions are when the immune system goes crazy when a normally harmless "invader" comes into the body. You can usually determine an allergy by inflammatory response (red, swelling, pain, loss of function, et al) and an abnormal presence of a specific antibodies (Type IgE I think). Epi-pen are commonly used for immediate aid. The idea is to open his throat back up and make his blood vessel smaller. Epinepherine is a stimulant hormone that is normally used for that. Get it? Epi-pen? Wikipedia will give you tons of information about it if you're still curious.