Rhinitis is commonly caused by a viral or bacterial infection, including the common cold, which is caused by Rhinoviruses and Coronaviruses, or bacterial sinusitis. Symptoms of the common cold include rhinorrhea, sore throat (pharyngitis), cough, congestion, and slight headache. Fever is rare in an uncomplicated common cold, except in children, who may have a fever, though even in children fever seldom rises above 102. Bacterial sinusitis should be suspected in the patient with cold symptoms in addition to fever of 102>, or in patients who have severe pain in the face.
Non-allergic rhinitis refers to runny nose that is not due to allergy.Also cause teary eyes . Non-allergic rhinitis can be classified as either non-inflammatory or inflammatory. One very common type of non-inflammatory, non-allergic rhinitis that is sometimes confused with allergy is called vasomotor rhinitis, in which certain non-allergic triggers such as smells, fumes, smoke, dusts, and temperature changes, cause rhinitis. There is still much to be learned about this entity, but it is thought that these non-allergic triggers cause dilation of the blood vessels in the lining of the nose, which results in swelling, and drainage. Vasomotor rhinitis can coexist with allergic rhinitis, and this is called "mixed rhinitis." (Middleton's Allergy Principles and Practice, seventh edition.) The pathology of vasomotor rhinitis is in fact not very well-understood and more research is needed. Vasomotor rhinitis appears to be significantly more common in women than men, leading some researchers to believe hormones to play a role. In general, age of onset occurs after 20 years of age, in contrast to allergic rhinitis which can be developed at any age. Individuals suffering from vasomotor rhinitis typically experience symptoms year-round, though symptoms may exacerbate in the spring and fall when rapid weather changes are more common. An estimated 17 million United States citizens have vasomotor rhinitis.
When an allergen such as pollen or dust is inhaled by an individual with a sensitized immune system, it triggers antibody production. These antibodies mostly bind to mast cells, which contain histamine. When the mast cells are stimulated by pollen and dust, histamine (and other chemicals) are released. This causes itching, swelling, and mucus production. Symptoms vary in severity between individuals. Very sensitive individuals can experience hives or other rashes. Particulate matter in polluted air and chemicals such as chlorine and detergents, which can normally be tolerated, can greatly aggravate the condition.
Sufferers might also find that cross-reactivity occurs. For example, someone allergic to birch pollen may also find that they have an allergic reaction to the skin of apples or potatoes. A clear sign of this is the occurrence of an itchy throat after eating an apple or sneezing when peeling potatoes or apples. This occurs because of similarities in the proteins of the pollen and the food. There are many cross-reacting substances.
Some disorders may be associated with allergies: Comorbidities include eczema, asthma, depression and migraine.
Allergies are common. Heredity and environmental exposures may contribute to a predisposition to allergies. It is roughly estimated that one in three people have an active allergy at any given time and at least three in four people develop an allergic reaction at least once in their lives.
The two categories of allergic rhinitis include:
- Seasonal – occurs particularly during pollen seasons. Seasonal allergic rhinitis does not usually develop until after 6 years of age.
- Perennial – occurs throughout the year. This type of allergic rhinitis is commonly seen in younger children.
On examination, persons with allergic rhinitis have characteristic physical findings that include conjunctival swelling and erythema, eyelid swelling, lower eyelid venous stasis (allergic shiners), lateral crease on the nose (allergic crease), swollen nasal turbinates, and middle ear effusion.
Allergy testing may reveal the specific allergens an individual is sensitive to. Skin testing is the most common method of allergy testing. This may include intradermal, scratch, patch, or other tests. Less commonly, the suspected allergen is dissolved and dropped onto the lower eyelid as a means of testing for allergies. (This test should only be done by a physician, never the patient, since it can be harmful if done improperly). In some individuals who cannot undergo skin testing (as determined by the doctor), the RAST blood test may be helpful in determining specific allergen sensitivity.
Allergic rhinitis triggered by the pollens of specific seasonal plants is commonly known as "hay fever", because it is most prevalent during haying season. However, it is possible to suffer from hay fever throughout the year. The pollen which causes hay fever varies between individuals and from region to region; generally speaking, the tiny, hardly visible pollens of wind-pollinated plants are the predominant cause. Pollens of insect-pollinated plants are too large to remain airborne and pose no risk. Examples of plants commonly responsible for hay fever include:
- Trees: such as pine , birch (''Betula''), alder (''Alnus''), cedar (''Cedrus''), hazel (''Corylus''), hornbeam (''Carpinus''), horse chestnut (''Aesculus''), willow (''Salix''), poplar (''Populus''), plane (''Platanus''), linden/lime (''Tilia'') and olive (''Olea''). In northern latitudes birch is considered to be the most important allergenic tree pollen, with an estimated 15–20% of hay fever sufferers sensitive to birch pollen grains. Olive pollen is most predominant in Mediterranean regions.
- Grasses (Family Poaceae): especially ryegrass (''Lolium'' sp.) and timothy (''Phleum pratense''). An estimated 90% of hay fever sufferers are allergic to grass pollen.
- Weeds: ragweed (''Ambrosia''), plantain (''Plantago''), nettle/parietaria (Urticaceae), mugwort (''Artemisia''), Fat hen (''Chenopodium'') and sorrel/dock (''Rumex'')
In addition to individual sensitivity and geographic differences in local plant populations, the amount of pollen in the air can be a factor in whether hay fever symptoms develop. Hot, dry, windy days are more likely to have increased amounts of pollen in the air than cool, damp, rainy days when most pollen is washed to the ground.
The time of year at which hay fever symptoms manifest themselves varies greatly depending on the types of pollen to which an allergic reaction is produced. The pollen count, in general, is highest from mid-spring to early summer. As most pollens are produced at fixed periods in the year, a long-term hay fever sufferer may also be able to anticipate when the symptoms are most likely to begin and end, although this may be complicated by an allergy to dust particles.
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