Allergies - overview

Allergy - allergies; Allergy - allergens

An allergy is an immune response or reaction to substances that are usually not harmful.

Allergic reactions

Allergic reaction can be provoked by skin contact with poison plants, chemicals and animal scratches, as well as by insect stings. Ingesting or inhaling substances like pollen, animal dander, molds and mildew, dust, nuts and shellfish, may also cause allergic reaction. Medications such as penicillin and other antibiotics are also to be taken with care, to assure an allergic reflex is not triggered.

Allergy symptoms

The immune system normally responds to harmful substances such as bacteria, viruses and toxins by producing symptoms such as runny nose and congestion, post-nasal drip and sore throat, and itchy ears and eyes. An allergic reaction can produce the same symptoms in response to substances that are generally harmless, like dust, dander or pollen. The sensitized immune system produces antibodies to these allergens, which cause chemicals called histamines to be released into the bloodstream, causing itching, swelling of affected tissues, mucus production, hives, rashes, and other symptoms. Symptoms vary in severity from person to person.

Histamine is released

Mast cells release histamine when an allergen is encountered. The histamine response can produce sneezing, itching, hives and watery eyes.

Introduction to allergy treatment

Treatment varies with the severity and type of allergy symptom. The first course of action is to avoid the allergen if possible. Medications such as antihistaimines are then usually prescribed to relieve the allergic symptoms. Immunotherapy, or "allergy shots", is occasionally recommended if the allergen cannot be avoided. It includes regular injections of the allergen, given in increasing doses that may "de-sensitize" the body to the allergen.

Hives (urticaria) on the arm

Hives (urticaria) are raised, red, itchy welts, seen here on the arm. The majority of urticaria develop as a result of allergic reactions. Occasionally, they may be associated with autoimmune diseases, infections (parasitosis), drugs, malignancy, or other causes.

Hives (urticaria) on the chest

Hives (urticaria) are raised, red, itchy welts, seen here on the chest. The majority of urticaria develop as a result of allergic reactions. Occasionally they may be associated with autoimmune diseases, infections (parasitosis), drugs, malignancy, or other causes.

Allergies

Heredity, environmental conditions, number and type of exposures and emotional factors can indicate a predisposition to allergies.

Antibodies

Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.

Causes

Symptoms

Exams and Tests

Treatment

Support Groups

Outlook (Prognosis)

Possible Complications

When to Contact a Medical Professional

Prevention