Anaphylactic reaction or Anaphylaxis is an allergic reaction to medication, foods, insect bites, or stings.
The most common foods that can cause Anaphylaxis is peanuts, tree nuts, shellfish, fish, milk, and eggs.
Medications such as aspirin and ibuprofen are known to be common for causing anaphylaxis.
The reason it does no occur the first time is because the first time you are exposed to your allergy your body produces IgE antibodies. The IgE antibodies then stick to the mast cells. When exposed at a later time to the same allergy the mast cells disintegrate, liberating heparin and histamines which cause Anaphylaxis.
This answer was edited by runningpoet 666 days ago.
Reason: clarity
