Why allergic reactions appear in some and don’t affect others?

Reasons and degree of allergies vary from person to person. That is the reason behind why some people are extremely vulnerable towards allergies while we cannot find a trace of it in others. Allergy, in majority of the cases, is hereditary and is passed through genes of the parents to the children. If one of your parents has allergies, you have 50% of chance to inherit susceptibility towards allergies. Children, whose both parents are allergic, have 75% of chance to inherit allergy from birth. Second reason behind case specific occurrence of allergy is the effectiveness of one’s immune system.

Allergy is our immune system’s hyper-alert towards external allergens. People having a stronger immune system are less vulnerable towards allergies. Those who lack this strength show the signs of allergy when exposed to allergens. Secretion of mediator hormones like histamine makes a person more vulnerable towards different types of allergies. If your body shows resistance to the excessive secretion Mediators, you are less vulnerable towards developing allergies. There are several medicines and vaccinations which can trigger allergies in some cases. Most common of them is aspirin. However, it does not mean that the same medicine or vaccine will create allergic reactions over all persons.