Allergy is defined as a disorder of the immune system often also referred to as atopy. Allergic reactions occur when a person’s immune system reacts to normally harmless substances in the environment.

2. Allergy :
An allergy is a specific reaction of the body's immune system to a
normally harmless substance, one that does not bother most people.
People who have allergies often are sensitive to more than one
substance.
Allergic reaction :
Normally, the immune system functions as the body's defense against
invading germs such as bacteria and viruses. In most allergic
reactions, however, the immune system is responding to a false alarm.
When an allergic person first comes into contact with an allergen, the
immune system treats the allergen as an invader and gets ready to
attack.

3. The signs and symptoms of airborne
allergies are familiar to many:
 Sneezing, often with a runny or
clogged nose
 Coughing and postnasal drip
 Itching eyes, nose, and throat
 Watering eyes
 Conjunctivitis

4. TYPES OF ALLERGIES :
 Food Allergy
 Pollen Allergy
 Mold allergy
 Dust Mite Allergy
 Animal Allergy
 Cockroach allergy
 Smoke Allergy

5.  Severe allergic reactions (anaphylaxis) need
to be treated with a medicine called
epinephrine, which can be life saving when
given right away. If you use epinephrine, call 911
and go straight to the hospital.
 The best way to reduce symptoms is to
avoid what causes your allergies. This is
especially important for food and drug allergies.
 There are several types of medications to
prevent and treat allergies. Which medicine your
doctor recommends depends on the type and
severity of your symptoms, your age, and
overall health.
 Illnesses that are caused by allergies (such
as asthma, hay fever, and eczema) may need
other
treatments.