Allergies are disorders of the immune system. Most allergies symptoms are a result of an immune system that responds to a "false alarm."

When a harmless substance such as dust, mold, or pollen is encountered by a person who is allergic to that substance, the immune system may react dramatically, by producing antibodies that "attack" the allergen (substances that produce allergic reactions).

The result of an allergen entering a susceptible person's body may include wheezing, itching, runny nose, and watery or itchy eyes, and other symptoms.

There are two types of swelling, called a "local" or "systemic" inflammatory response to allergens.

An example of a local inflammatory response is when your allergies affect you in the nose and experience swelling of the nasal mucosa (allergic rhinitis). In this case, you will probably find yourself performing the "nasal salute" because your unusually itchy nose will force you to wipe your nose in an upward direction. If the allergies affect your eyes, redness and itching of the conjunctiva often follows.

Systemic allergic responses are more serious than the local response. Depending on the severity of your allergic reaction, allergies can cause cutaenous reactions, bronchoconstriction, edema, hypertension, coma, and even death.

Some common allergens include:

food allergies
Foods. Food allergies are most common in infants and often go away as people get older. The foods that people are most commonly allergic to are milk and other dairy products, eggs, wheat, soy, peanuts and tree nuts, and seafood.

Insect bites and stings. The venom (poison) in insect bites and stings can cause allergic reactions, and can be severe and even cause an anaphylactic reaction in some people.

Airborne particles. Often called environmental allergens, these are the most common allergens.

Medicines. Antibiotics - medications used to treat infections - are the most common type of medicines that cause allergic reactions.

Chemicals. Some cosmetics or laundry detergents can make people break out in an itchy rash (hives).

The most effective way of treating allergies is to avoid all contact with the allergen causing the reaction. Allergic reactions can be treated through the use of over-the-counter medications such as antihistamines, decongestants, nasal sprays, eye drops, allergy shots and a variety of medical inhibitors.

Allergies can also be treated naturally through the use of herbal supplements and natural products, such as saline.

Allergic reactions can be very serious. This is called anaphylactic shock. It is a sudden, severe allergic reaction that involves the whole body and it usually happens within minutes of coming into contact with a particular allergen.

The allergic symptoms of anaphylactic shock affect the respiratory and circulatory system and include the following:
  • raised blood pressure,
  • swelling, and
  • breathing difficulties.
Allergies infographic
Allergies infographic