Immune system is the defense mechanism of the body and protects the body from the invading germs and bacteria. However, in allergic reactions, the body falsely reacts to a substance that it considers foreign and dangerous. In response the body releases histamine leading to inflammation of the body. Normally if an allergen enters through the nasal cavity, the mucus inside the nose moves the allergen to the throat which can be swallowed or coughed out. However, in sensitive people, as soon as the allergen enters the body reacts and produces histamine leading to inflammation. Some of the types and main triggers of allergies are as follows:

Medication Allergy
Medication allergy or reactivity towards medicines is a rare allergy and is primarily responsible because of the compromised immune system of the body. The allergic reactions that can be seen are wheezing, nausea, diarrhea, swelling of mouth and throat, abdominal pain, fainting and even shortness of breath. In some worse conditions even anaphylaxis. The main triggers of this type of allergy are

• True allergic reaction due to IgE and immune system
• Non allergic reaction

Often, overdosing certain medications can lead an allergy

Food Allergy
Allergic reaction when the body identifies a food as harmful and responds causing allergic symptoms. Food that causes allergic reaction are called allergens, and the main triggers can be broadly classified as into two types:

• Immunoglobulin E Mediated
  When the body comes in contact with foods like dairy products, red meat, egg, peanut, wheat, shellfish, and soy. The immunoglobulin E synthesized by the immune system reacts with these foods and can cause an allergic reaction.
• Non IgE Mediated
  In some cases, the other parts of the body react to the food that has been consumed and the immune system doesn’t not play a role in the allergic reaction.

Every individual has different levels of tolerance toward different foods and the allergic reaction can vary from individual to individual.

Insect Allergy
Insects can sting or bite, and the toxin in their sting or bite can trigger an allergic reaction. In some cases, even the presence of an insect in the surrounding can trigger an allergic reaction. The triggers can be classified into following

• Insect Sting
  Insects like bees, wasps, hornets, fire ants inject their venom into the body which triggers an allergic reaction. Recovery is within hours but more the toxic the venom is more is the fatality.
• Insect Bite
  Insects like bed bugs, mosquitoes, ticks, fleas, and certain flies are the common ones that bite humans. People usually suffer from itchy and red swollen skin at the site of the bite. However, in some cases, a bite can lead to an allergic reaction that reflects somewhere else. For e.g.: a bite from lone star tick can make an individual allergic towards red meat.
• Pests
  The most common ones in the household, cockroaches can trigger asthma like symptoms in some individuals. The droppings of cockroach contain a protein that can trigger allergy. Pests like dust mites also are responsible for asthma in some individuals.

Allergic reactions are unavoidable as long as humans come in contact with different elements of the environment. The best solution is to undergo a test of allergies and determine which types of triggers one should be wary of.