Perennial Allergies  Hay fever is one of several types of
allergies that cause similar allergy symptoms. Itchy eyes
(allergic conjunctivitis), nasal congestion, excess mucus, and
difficulty breathing are common symptoms in people with hay
fever, as well as other allergic conditions. Wheezing, dark eye
circles, and allergic cough may be caused by a seasonal allergy
to high pollen levels (as is the case with hay fever) or to year
round substances (e.g., pet allergies, dust mite allergies, mold
allergies).  Pet Allergies  Pet allergies are very common and
result when people inherit or develop a hypersensitivity to
animal saliva, dander (such as cat dander), or urine. These
substances, known as allergens when they cause an allergic
reaction, are sticky and have a tendency to collect on surfaces
in the home and elsewhere. When a person who has a pet allergy
comes in contact with these allergens, allergy symptoms such as
swollen, itchy eyes, nasal congestion, and difficult breathing
develop within several hours.  A