In the case of exposure to Why does the body react to some substances and not others? Each person’s immune system is equipped with certain sensitivities that might trigger an allergic response. Sourced from: http://www.richmondallergy.com/what-are-allergens.html
Some of the things that people are allergic to are as common as they are dangerous. Whoever thought that latex could be irritating yet it is soft.
In fact around 3% of the adult population have some degree of allergy to insect stings. Sourced from: http://www.planetdeadly.com/nature/dangerous-allergies
An allergist can help identify the cause. Sourced from: http://www.webmd.com/allergies/anaphylaxis-15/slideshow-allergy-triggers