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Allergic rhinitis, of which the seasonal type is called hay fever, is a type of inflammation in the nose that occurs when the
immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splint ...
overreacts to
allergen An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies. In technical terms ...
s in the air. Signs and symptoms include a runny or stuffy nose,
sneezing A sneeze (also known as sternutation) is a semi-autonomous, convulsive expulsion of air from the lungs through the nose and mouth, usually caused by foreign particles irritating the nasal mucosa. A sneeze expels air forcibly from the mouth and ...
, red, itchy, and watery eyes, and swelling around the eyes. The fluid from the nose is usually clear. Symptom onset is often within minutes following allergen exposure, and can affect sleep and the ability to work or study. Some people may develop symptoms only during specific times of the year, often as a result of pollen exposure. Many people with allergic rhinitis also have
asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
,
allergic conjunctivitis Allergic conjunctivitis (AC) is inflammation of the conjunctiva (the membrane covering the white part of the eye) due to allergy. Although allergens differ among patients, the most common cause is hay fever. Symptoms consist of redness (mainly due ...
, or atopic dermatitis. Allergic rhinitis is typically triggered by environmental allergens such as pollen, pet hair, dust, or
mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...
. Inherited
genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...
and environmental exposures contribute to the development of allergies. Growing up on a farm and having multiple siblings decreases this risk. The underlying mechanism involves IgE antibodies that attach to an allergen, and subsequently result in the release of inflammatory chemicals such as histamine from
mast cells A mast cell (also known as a mastocyte or a labrocyte) is a resident cell of connective tissue that contains many granules rich in histamine and heparin. Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a ...
. It causes mucous membranes in the nose, eyes and throat to become inflamed and itchy as they work to eject the allergen. Diagnosis is typically based on a combination of symptoms and a
skin prick test Skin allergy testing comprises a range of methods for medical diagnosis of allergies that attempts to provoke a small, controlled, allergic response. Methods A microscopic amount of an allergen is introduced to a patient's skin by various mean ...
or blood tests for allergen-specific IgE antibodies. These tests, however, can be falsely positive. The symptoms of allergies resemble those of the common cold; however, they often last for more than two weeks and, despite the common name, typically do not include a
fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...
. Exposure to animals early in life might reduce the risk of developing these specific allergies. Several different types of medications reduce allergic symptoms, including nasal steroids,
antihistamine Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provid ...
s, such as
diphenhydramine Diphenhydramine (DPH) is an antihistamine and sedative mainly used to treat allergies, insomnia, and symptoms of the common cold. It is also less commonly used for tremor in parkinsonism, and nausea. It is taken by mouth, injected into ...
, cromolyn sodium, and
leukotriene receptor antagonists An antileukotriene, also known as leukotriene modifier and leukotriene receptor antagonist, is a medication which functions as a leukotriene-related enzyme inhibitor (arachidonate 5-lipoxygenase) or leukotriene receptor antagonist (cysteinyl leukot ...
such as montelukast. Oftentimes, medications do not completely control symptoms, and they may also have side effects. Exposing people to larger and larger amounts of allergen, known as
allergen immunotherapy Allergen immunotherapy, also known as desensitization or hypo-sensitization, is a medical treatment for environmental allergies, such as insect bites, and asthma. Immunotherapy involves exposing people to larger and larger amounts of allergen in ...
(AIT), is often effective. The allergen can be given as an injection under the skin or as a tablet under the tongue. Treatment typically lasts three to five years, after which benefits may be prolonged. Allergic rhinitis is the type of
allergy Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derm ...
that affects the greatest number of people. In Western countries, between 10 and 30% of people are affected in a given year. It is most common between the ages of twenty and forty. The first accurate description is from the 10th-century physician
Abu Bakr al-Razi Abū Bakr al-Rāzī (full name: ar, أبو بکر محمد بن زکریاء الرازي, translit=Abū Bakr Muḥammad ibn Zakariyyāʾ al-Rāzī, label=none), () rather than ar, زکریاء, label=none (), as for example in , or in . In m ...
. In 1859,
Charles Blackley Charles Harrison Blackley (5 April 1820 – 4 September 1900) was the discoverer of the mechanism behind allergic rhinitis caused by pollen, commonly called hay fever. The isolation of hay fever as a condition had been known since 1819 through t ...
identified pollen as the cause. In 1906, the mechanism was determined by
Clemens von Pirquet Clemens Peter Freiherr von Pirquet (12 May 187428 February 1929) was an Austrian scientist and pediatrician best known for his contributions to the fields of bacteriology and immunology. Career Born in Vienna, he studied theology at the Universit ...
. The link with hay came about due to an early (and incorrect) theory that the symptoms were brought about by the smell of new hay. Although the scent per se is irrelevant, the correlation with hay remains more than random, as peak hay-harvesting season overlaps with peak pollen season, and hay-harvesting work puts people in close contact with seasonal allergens.


Signs and symptoms

The characteristic symptoms of allergic rhinitis are:
rhinorrhea Rhinorrhea, rhinorrhoea, or informally runny nose is the free discharge of a thin mucus fluid from the nose; it is a common condition. It is a common symptom of allergies ( hay fever) or certain viral infections, such as the common cold or CO ...
(excess nasal secretion),
itching Itch (also known as pruritus) is a Wikt:sensation, sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of Sensory system, sensory experience. Itch has many similarities to pain, ...
, sneezing fits, and nasal congestion and obstruction. Characteristic physical findings include
conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium ...
l swelling and
erythema Erythema (from the Greek , meaning red) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not asso ...
, eyelid swelling with
Dennie–Morgan fold A Dennie–Morgan fold, also known as a Dennie–Morgan line or an infraorbital fold, is a fold or line in the skin below the lower eyelid. It can simply be an ethnic/genetic trait, but was found in one study to occur in 25% of patients with atopic ...
s, lower eyelid venous stasis (rings under the eyes known as " allergic shiners"), swollen
nasal turbinates In anatomy, a nasal concha (), plural conchae (), also called a nasal turbinate or turbinal, is a long, narrow, curled shelf of bone tissue, bone that protrudes into the breathing passage of the nose in humans and various animals. The conchae ar ...
, and middle ear effusion. There can also be behavioral signs; in order to relieve the irritation or flow of mucus, people may wipe or rub their nose with the palm of their hand in an upward motion: an action known as the "nasal salute" or the " allergic salute". This may result in a crease running across the nose (or above each nostril if only one side of the nose is wiped at a time), commonly referred to as the " transverse nasal crease", and can lead to permanent physical deformity if repeated enough. People might also find that
cross-reactivity Cross-reactivity, in a general sense, is the reactivity of an observed agent which initiates reactions outside the main reaction expected. This has implications for any kind of test or assay, including diagnostic tests in medicine, and can be a c ...
occurs. For example, people 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. Hay fever is not a true fever, meaning it does not cause a core body temperature in the fever over 37.5–38.3 °C (99.5–100.9 °F).


Cause

Pollen is often considered as a cause of allergic rhinitis, hence called hay fever (See sub-section below). Predisposing factors to allergic rhinitis include eczema (atopic dermatitis) and asthma. These three conditions can often occur together which is referred to as the atopic triad. Additionally, environmental exposures such as air pollution and maternal tobacco smoking can increase an individual's chances of developing allergies.


Pollen-related causes

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 have allergic rhinitis throughout the year. The pollen that causes hay fever varies between individuals and from region to region; in general, the tiny, hardly visible pollens of wind-pollinated
plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...
s 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 (''
Pinus A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae. The World Flora Online created by the Royal Botanic Gardens, Kew and Missouri Botanical Garden ...
''), mulberry ('' Morus''), birch (''
Betula A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' contains 30 t ...
''), alder ('' Alnus''), cedar (''
Cedrus ''Cedrus'', common English name cedar, is a genus of coniferous trees in the plant family Pinaceae (subfamily Abietoideae). They are native to the mountains of the western Himalayas and the Mediterranean region, occurring at altitudes of 1,500 ...
''), hazel (''
Corylus The hazel (''Corylus'') is a genus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is usually placed in the birch family Betulaceae,Germplasmgobills Information Network''Corylus''Rushforth, K. (1999). ...
''), hornbeam ('' Carpinus''), horse chestnut (''
Aesculus The genus ''Aesculus'' ( or ), with species called buckeye and horse chestnut, comprises 13–19 species of flowering plants in the family Sapindaceae. They are trees and shrubs native to the temperate Northern Hemisphere, with six spe ...
''), willow (''
Salix Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...
''), poplar ('' Populus''), plane (''
Platanus ''Platanus'' is a genus consisting of a small number of tree species native to the Northern Hemisphere. They are the sole living members of the family Platanaceae. All mature members of ''Platanus'' are tall, reaching in height. All except ...
''), linden/lime ('' Tilia''), and olive (''
Olea ''Olea'' ( ) is a genus of about 40 species in the family Oleaceae, native to warm temperate and tropical regions of the Middle East, southern Europe, Africa, southern Asia, and Australasia. They are evergreen trees and shrubs, with small ...
''). In northern latitudes, birch is considered to be the most common allergenic tree pollen, with an estimated 15–20% of people with hay fever sensitive to birch pollen grains. A major antigen in these is a protein called Bet V I. Olive pollen is most predominant in Mediterranean regions.
Hay fever in Japan is most commonly caused by pollen from ''Cryptomeria japonica'' (known as ''sugi'' in Japanese and often translated as "cedar" though it is not a member of the Cedrus genus) and Japanese cypress (known as ''hinoki''), two native Japanese tree sp ...
is caused primarily by
sugi ''Cryptomeria'' (literally "hidden parts") is a monotypic genus of conifer in the cypress family Cupressaceae, formerly belonging to the family Taxodiaceae. It includes only one species, ''Cryptomeria japonica'' ( syn. ''Cupressus japonica'' ...
(''Cryptomeria japonica'') and
hinoki ''Chamaecyparis obtusa'' (Japanese cypress, hinoki cypress or hinoki; ja, 檜 or , ) is a species of cypress native to central Japan in East Asia, and widely cultivated in the temperate northern hemisphere for its high-quality timber and orname ...
(''Chamaecyparis obtusa'') tree pollen. ** "Allergy friendly" trees include: female ash, red
maple ''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http ...
,
yellow poplar ''Liriodendron tulipifera''—known as the tulip tree, American tulip tree, tulipwood, tuliptree, tulip poplar, whitewood, fiddletree, and yellow-poplar—is the North American representative of the two-species genus ''Liriodendron'' (the other ...
,
dogwood ''Cornus'' is a genus of about 30–60 species of woody plants in the family Cornaceae, commonly known as dogwoods, which can generally be distinguished by their blossoms, berries, and distinctive bark. Most are deciduous trees or shru ...
,
magnolia ''Magnolia'' is a large genus of about 210 to 340The number of species in the genus ''Magnolia'' depends on the taxonomic view that one takes up. Recent molecular and morphological research shows that former genera ''Talauma'', ''Dugandiodendro ...
,
double-flowered "Double-flowered" describes varieties of flowers with extra petals, often containing flowers within flowers. The double-flowered trait is often noted alongside the scientific name with the abbreviation ''fl. pl.'' (''flore pleno'', a Latin ablat ...
cherry, fir, spruce, and flowering plum. * Grasses (Family Poaceae): especially ryegrass ('' Lolium'' sp.) and timothy ('' Phleum pratense''). An estimated 90% of people with hay fever are allergic to grass pollen. * Weeds:
ragweed Ragweeds are flowering plants in the genus ''Ambrosia'' in the aster family, Asteraceae. They are distributed in the tropical and subtropical regions of the Americas, especially North America,Plantago ''Plantago'' is a genus of about 200 species of flowering plants in the family Plantaginaceae, commonly called plantains or fleaworts. The common name plantain is shared with the unrelated cooking plantain. Most are herbaceous plants, though ...
''), nettle/parietaria (
Urticaceae The Urticaceae are a family, the nettle family, of flowering plants. The family name comes from the genus ''Urtica''. The Urticaceae include a number of well-known and useful plants, including nettles in the genus ''Urtica'', ramie (''Boehmeri ...
),
mugwort Mugwort is a common name for several species of aromatic flowering plants in the genus '' Artemisia.'' In Europe, mugwort most often refers to the species ''Artemisia vulgaris'', or common mugwort. In East Asia the species ''Artemisia argyi'' is ...
(''Artemisia Vulgaris''), Fat hen (''
Chenopodium ''Chenopodium'' is a genus of numerous species of perennial or annual herbaceous flowering plants known as the goosefoots, which occur almost anywhere in the world. It is placed in the family Amaranthaceae in the APG II system; older classific ...
''), and sorrel/dock ('' Rumex'') Allergic rhinitis may also be caused by allergy to
Balsam of Peru Balsam of Peru or Peru balsam, also known and marketed by many other names, is a balsam derived from a tree known as ''Myroxylon balsamum'' var. ''pereirae''; it is found in El Salvador, where it is an endemic species. Balsam of Peru is used i ...
, which is in various fragrances and other products.


Genetic factors

The causes and pathogenesis of allergic rhinitis are hypothesized to be affected by both genetic and environmental factors, with many recent studies focusing on specific loci that could be potential therapeutic targets for the disease.
Genome-wide association studies In genomics, a genome-wide association study (GWA study, or GWAS), also known as whole genome association study (WGA study, or WGAS), is an observational study of a genome-wide set of genetic variants in different individuals to see if any varian ...
(GWAS) have identified a number of different loci and genetic pathways that seem to mediate the body's response to allergens and promote the development of allergic rhinitis, with some of the most promising results coming from studies involving
single-nucleotide polymorphisms In genetics, a single-nucleotide polymorphism (SNP ; plural SNPs ) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a sufficiently larg ...
(SNPs) in the
interleukin-33 Interleukin 33 (IL-33) is a protein that in humans is encoded by the ''IL33'' gene. Interleukin 33 is a member of the IL-1 family that potently drives production of T helper-2 (Th2)-associated cytokines (e.g., IL-4). IL33 is a ligand for ST2 ...
(IL-33) gene. The IL-33 protein that is encoded by the IL-33 gene is part of the interleukin family of cytokines that interact with T-helper 2 (Th2) cells, a specific type of
T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...
. Th2 cells contribute to the body's inflammatory response to allergens, and specific ST2 receptors, also known as
IL1RL1 Interleukin 1 receptor-like 1, also known as IL1RL1 and ST2, is a protein that in humans is encoded by the ''IL1RL1'' gene. Function IL1RL1 is a member of the Toll-like receptor superfamily based on the function of its intracellular TIR domain ...
, on these cells bind to the ligand IL-33 protein. This IL-33/ST2 signaling pathway has been found to be one of the main genetic determinants in bronchial
asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
pathogenesis, and because of the pathological linkage between asthma and rhinitis, the experimental focus of IL-33 has now turned to its role in the development of allergic rhinitis in humans and mouse models. Recently, it was found that allergic rhinitis patients expressed higher levels of IL-33 in their nasal epithelium and had a higher concentration of ST2 serum in nasal passageways following their exposure to pollen and other allergens, indicating that this gene and its associated receptor are expressed at a higher rate in allergic rhinitis patients. In a 2020 study on polymorphisms of the IL-33 gene and their link to allergic rhinitis within the Han Chinese population, researchers found that five SNPs specifically contributed to the pathogenesis of allergic rhinitis, with three of those five SNPs previously identified as genetic determinants for asthma. Another study focusing on Han Chinese children found that certain SNPs in the protein tyrosine phosphatase non-receptor 22 ( PTPN22) gene and cytotoxic T-lymphocyte-associated antigen 4 (
CTLA-4 CTLA-4 or CTLA4 (cytotoxic T-lymphocyte-associated protein 4), also known as CD152 ( cluster of differentiation 152), is a protein receptor that functions as an immune checkpoint and downregulates immune responses. CTLA-4 is constitutively exp ...
) gene can be associated with childhood allergic rhinitis and allergic asthma. The encoded PTPN22 protein, which is found primarily in
lymphoid The lymphatic system, or lymphoid system, is an organ system in vertebrates that is part of the immune system, and complementary to the circulatory system. It consists of a large network of lymphatic vessels, lymph nodes, lymphatic or lymphoid o ...
tissue, acts as a
post-translational Post-translational modification (PTM) is the covalent and generally enzymatic modification of proteins following protein biosynthesis. This process occurs in the endoplasmic reticulum and the golgi apparatus. Proteins are synthesized by ribosom ...
regulator by removing phosphate groups from targeted proteins. Importantly, PTPN22 can affect the phosphorylation of T cell responses, and thus the subsequent proliferation of the T cells. As mentioned earlier, T cells contribute to the body's inflammatory response in a variety of ways, so any changes to the cells' structure and function can have potentially deleterious effects on the body's inflammatory response to allergens. To date, one SNP in the PTPN22 gene has been found to be significantly associated with allergic rhinitis onset in children. On the other hand, CTLA-4 is an immune-checkpoint protein that helps mediate and control the body's immune response to prevent overactivation. It is expressed only in T cells as a glycoprotein for the Immunoglobulin (Ig) protein family, also known as antibodies. There have been two SNPs in CTLA-4 that were found to be significantly associated with childhood allergic rhinitis. Both SNPs most likely affect the associated protein's shape and function, causing the body to exhibit an overactive immune response to the posed allergen. The polymorphisms in both genes are only beginning to be examined, therefore more research is needed to determine the severity of the impact of polymorphisms in the respective genes. Finally, epigenetic alterations and associations are of particular interest to the study and ultimate treatment of allergic rhinitis. Specifically,
microRNAs MicroRNA (miRNA) are small, single-stranded, non-coding RNA molecules containing 21 to 23 nucleotides. Found in plants, animals and some viruses, miRNAs are involved in RNA silencing and post-transcriptional regulation of gene expression. miR ...
(miRNA) are hypothesized to be imperative to the pathogenesis of allergic rhinitis due to the
post-transcriptional regulation Post-transcriptional regulation is the control of gene expression at the RNA level. It occurs once the RNA polymerase has been attached to the gene's promoter and is synthesizing the nucleotide sequence. Therefore, as the name indicates, it occ ...
and repression of translation in their mRNA complement. Both miRNAs and their common carrier vessel exosomes have been found to play a role in the body's immune and inflammatory responses to allergens. miRNAs are housed and packaged inside of exosomes until they are ready to be released into the section of the cell that they are coded to reside and act. Repressing the translation of proteins can ultimately repress parts of the body's immune and inflammatory responses, thus contributing to the pathogenesis of allergic rhinitis and other autoimmune disorders. There are many miRNAs that have been deemed potential therapeutic targets for the treatment of allergic rhinitis by many different researchers, with the most widely studied being miR-133, miR-155, miR-205, miR-498, and let-7e.


Diagnosis

Allergy testing may reveal the specific allergens to which an individual is sensitive. Skin testing is the most common method of allergy testing. This may include a patch test to determine if a particular substance is causing the rhinitis, or an intradermal, scratch, or other test. Less commonly, the suspected allergen is dissolved and dropped onto the lower eyelid as a means of testing for allergies. This test should be done only by a physician, since it can be harmful if done improperly. In some individuals not able to undergo skin testing (as determined by the doctor), the RAST blood test may be helpful in determining specific allergen sensitivity. Peripheral eosinophilia can be seen in differential leukocyte count. Allergy testing is not definitive. At times, these tests can reveal positive results for certain allergens that are not actually causing symptoms, and can also not pick up allergens that do cause an individual's symptoms. The intradermal allergy test is more sensitive than the skin prick test, but is also more often positive in people that do not have symptoms to that allergen. Even if a person has negative skin-prick, intradermal and blood tests for allergies, they may still have allergic rhinitis, from a local allergy in the nose. This is called local allergic rhinitis. Specialized testing is necessary to diagnose local allergic rhinitis.


Classification

* Seasonal allergic rhinitis (hay fever): Caused by seasonal peaks in the airborne load of pollens. * Perennial allergic rhinitis (nonseasonal allergic rhinitis; atopic rhinitis): Caused by allergens present throughout the year (e.g., dander). Allergic rhinitis may be seasonal, perennial, or episodic. Seasonal allergic rhinitis occurs in particular during pollen seasons. It does not usually develop until after 6 years of age. Perennial allergic rhinitis occurs throughout the year. This type of allergic rhinitis is commonly seen in younger children. Allergic rhinitis may also be classified as mild-intermittent, moderate-severe intermittent, mild-persistent, and moderate-severe persistent. Intermittent is when the symptoms occur <4 days per week or <4 consecutive weeks. Persistent is when symptoms occur >4 days/week and >4 consecutive weeks. The symptoms are considered mild with normal sleep, no impairment of daily activities, no impairment of work or school, and if symptoms are not troublesome. Severe symptoms result in sleep disturbance, impairment of daily activities, and impairment of school or work.


Local allergic rhinitis

Local allergic rhinitis is an allergic reaction in the nose to an allergen, without systemic allergies. So skin-prick and blood tests for allergy are negative, but there are IgE antibodies produced in the nose that react to a specific
allergen An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies. In technical terms ...
. Intradermal skin testing may also be negative. The symptoms of local allergic rhinitis are the same as the symptoms of allergic rhinitis, including symptoms in the eyes. Just as with allergic rhinitis, people can have either seasonal or perennial local allergic rhinitis. The symptoms of local allergic rhinitis can be mild, moderate, or severe. Local allergic rhinitis is associated with
conjunctivitis Conjunctivitis, also known as pink eye, is inflammation of the outermost layer of the white part of the eye and the inner surface of the eyelid. It makes the eye appear pink or reddish. Pain, burning, scratchiness, or itchiness may occur. The ...
and
asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
. In one study, about 25% of people with rhinitis had local allergic rhinitis. In several studies, over 40% of people having been diagnosed with
nonallergic rhinitis Nonallergic rhinitis is rhinitis—inflammation of the inner part of the nose—not caused by an allergy. Nonallergic rhinitis displays symptoms including chronic sneezing or having a congested, drippy nose, without an identified allergic reaction ...
were found to actually have local allergic rhinitis. Steroid nasal sprays and oral antihistamines have been found to be effective for local allergic rhinitis. As of 2014, local allergenic rhinitis had mostly been investigated in Europe; in the United States, the nasal provocation testing necessary to diagnose the condition was not widely available.


Prevention

Prevention often focuses on avoiding specific allergens that cause an individual's symptoms. These methods include not having pets, not having carpets or upholstered furniture in the home, and keeping the home dry. Specific anti-allergy zippered covers on household items like pillows and mattresses have also proven to be effective in preventing dust mite allergies. Studies have shown that growing up on a farm and having many older siblings can decrease an individual's risk for developing allergic rhinitis. Studies in young children have shown that there is higher risk of allergic rhinitis in those who have early exposure to foods or formula or heavy exposure to cigarette smoking within the first year of life.


Treatment

The goal of rhinitis treatment is to prevent or reduce the symptoms caused by the inflammation of affected tissues. Measures that are effective include avoiding the allergen. Intranasal corticosteroids are the preferred medical treatment for persistent symptoms, with other options if this is not effective. Second line therapies include
antihistamines Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides re ...
,
decongestants A decongestant, or nasal decongestant, is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine (the latter ...
,
cromolyn Cromoglicic acid ( INN)—also referred to as cromolyn (USAN), cromoglycate (former BAN), or cromoglicate—is traditionally described as a mast cell stabilizer, and is commonly marketed as the sodium salt sodium cromoglicate or cromolyn sodium. ...
,
leukotriene receptor antagonists An antileukotriene, also known as leukotriene modifier and leukotriene receptor antagonist, is a medication which functions as a leukotriene-related enzyme inhibitor (arachidonate 5-lipoxygenase) or leukotriene receptor antagonist (cysteinyl leukot ...
, and nasal irrigation. Antihistamines by mouth are suitable for occasional use with mild intermittent symptoms.
Mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear e ...
-proof covers, air filters, and withholding certain foods in childhood do not have evidence supporting their effectiveness.


Antihistamines

Antihistamine Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provid ...
drugs can be taken orally and nasally to control symptoms such as sneezing, rhinorrhea, itching, and conjunctivitis. It is best to take oral antihistamine medication before exposure, especially for seasonal allergic rhinitis. In the case of nasal antihistamines like azelastine antihistamine nasal spray, relief from symptoms is experienced within 15 minutes allowing for a more immediate 'as-needed' approach to dosage. There is not enough evidence of antihistamine efficacy as an add-on therapy with nasal steroids in the management of intermittent or persistent allergic rhinitis in children, so its adverse effects and additional costs must be considered. Ophthalmic antihistamines (such as azelastine in eye drop form and ketotifen) are used for conjunctivitis, while intranasal forms are used mainly for sneezing, rhinorrhea, and nasal pruritus. Antihistamine drugs can have undesirable side-effects, the most notable one being
drowsiness Somnolence (alternatively sleepiness or drowsiness) is a state of strong desire for sleep, or sleeping for unusually long periods (compare hypersomnia). It has distinct meanings and causes. It can refer to the usual state preceding falling asleep ...
in the case of oral antihistamine tablets. First-generation antihistamine drugs such as
diphenhydramine Diphenhydramine (DPH) is an antihistamine and sedative mainly used to treat allergies, insomnia, and symptoms of the common cold. It is also less commonly used for tremor in parkinsonism, and nausea. It is taken by mouth, injected into ...
cause drowsiness, while second- and third-generation antihistamines such as
cetirizine Cetirizine, sold under the brand name Zyrtec among others, is a second-generation antihistamine used to treat allergic rhinitis (hay fever), dermatitis, and urticaria (hives). It is taken by mouth. Effects generally begin within thirty minutes a ...
and
loratadine Loratadine, sold under the brand name Claritin among others, is a medication used to treat allergies. This includes allergic rhinitis (hay fever) and hives. It is also available in combination with pseudoephedrine, a decongestant, known as lora ...
are less likely to. Pseudoephedrine is also indicated for vasomotor rhinitis. It is used only when nasal congestion is present and can be used with antihistamines. In the United States, oral decongestants containing pseudoephedrine must be purchased behind the pharmacy counter in an effort to prevent the manufacturing of methamphetamine. Desloratadine/pseudoephedrine can also be used for this condition


Steroids

Intranasal corticosteroids are used to control symptoms associated with sneezing, rhinorrhea, itching, and nasal congestion. Steroid
nasal spray Nasal sprays are used to deliver medications locally in the nasal cavities or systemically. They are used locally for conditions such as nasal congestion and allergic rhinitis. In some situations, the nasal delivery route is preferred for syst ...
s are effective and safe, and may be effective without oral antihistamines. They take several days to act and so must be taken continually for several weeks, as their therapeutic effect builds up with time. In 2013, a study compared the efficacy of mometasone furoate nasal spray to betamethasone oral tablets for the treatment of people with seasonal allergic rhinitis and found that the two have virtually equivalent effects on nasal symptoms in people. Systemic steroids such as
prednisone Prednisone is a glucocorticoid medication mostly used to suppress the immune system and decrease inflammation in conditions such as asthma, COPD, and rheumatologic diseases. It is also used to treat high blood calcium due to cancer and ad ...
tablets and intramuscular triamcinolone acetonide or
glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every verteb ...
(such as betamethasone) injection are effective at reducing nasal inflammation, but their use is limited by their short duration of effect and the side-effects of prolonged steroid therapy.


Other

Other measures that may be used second line include:
decongestant A decongestant, or nasal decongestant, is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine (the latter ...
s,
cromolyn Cromoglicic acid ( INN)—also referred to as cromolyn (USAN), cromoglycate (former BAN), or cromoglicate—is traditionally described as a mast cell stabilizer, and is commonly marketed as the sodium salt sodium cromoglicate or cromolyn sodium. ...
, leukotriene receptor antagonists, and nonpharmacologic therapies such as nasal irrigation.
Topical decongestant Topical decongestants are decongestants applied directly to the nasal cavity. Their effectiveness by themselves in the common cold appears to have a small benefit in adults. Topical decongestants should only be used by patients for a maximum of 5� ...
s may also be helpful in reducing symptoms such as nasal congestion, but should not be used for long periods, as stopping them after protracted use can lead to a rebound nasal congestion called rhinitis medicamentosa. For nocturnal symptoms, intranasal corticosteroids can be combined with nightly
oxymetazoline Oxymetazoline, sold under the brand name Afrin among others, is a topical decongestant and vasoconstrictor medication. It is available over-the-counter as a nasal spray to treat nasal congestion and nosebleeds, as eyedrops to treat eye rednes ...
, an adrenergic alpha-agonist, or an antihistamine nasal spray without risk of rhinitis medicamentosa. Nasal saline irrigation (a practice where salt water is poured into the nostrils), may have benefits in both adults and children in relieving the symptoms of allergic rhinitis and it is unlikely to be associated with adverse effects.


Allergen immunotherapy

Allergen immunotherapy Allergen immunotherapy, also known as desensitization or hypo-sensitization, is a medical treatment for environmental allergies, such as insect bites, and asthma. Immunotherapy involves exposing people to larger and larger amounts of allergen in ...
(AIT, also termed desensitization) treatment involves administering doses of allergens to accustom the body to substances that are generally harmless (pollen,
house dust mites House dust mites (HDM, or simply dust mites) are various species of acariform mites belonging to the family Pyroglyphidae that are found in association with dust in dwellings. They are known for causing allergies. Biology Species The current ...
), thereby inducing specific long-term tolerance. Allergen immunotherapy is the only treatment that alters the disease mechanism. Immunotherapy can be administered orally (as sublingual tablets or sublingual drops), or by injections under the skin (subcutaneous). Subcutaneous immunotherapy is the most common form and has the largest body of evidence supporting its effectiveness.


Alternative medicine

There are no forms of complementary or alternative medicine that are evidence-based for allergic rhinitis. Therapeutic efficacy of alternative treatments such as
acupuncture Acupuncture is a form of alternative medicine and a component of traditional Chinese medicine (TCM) in which thin needles are inserted into the body. Acupuncture is a pseudoscience; the theories and practices of TCM are not based on scientif ...
and homeopathy is not supported by available evidence. While some evidence shows that acupuncture is effective for rhinitis, specifically targeting the sphenopalatine ganglion acupoint, these trials are still limited. Overall, the quality of evidence for complementary-alternative medicine is not strong enough to be recommended by the
American Academy of Allergy, Asthma and Immunology Founded in 1943, the American Academy of Allergy, Asthma & Immunology (AAAAI) is a professional medical membership organization of nearly 6,800 allergist/ immunologists and related professionals around the world with advanced training and experie ...
.


Epidemiology

Allergic rhinitis is the type of
allergy Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derm ...
that affects the greatest number of people. In Western countries, between 10 and 30 percent of people are affected in a given year. It is most common between the ages of twenty and forty.


History

The first accurate description is from the 10th century physician
Rhazes Abū Bakr al-Rāzī (full name: ar, أبو بکر محمد بن زکریاء الرازي, translit=Abū Bakr Muḥammad ibn Zakariyyāʾ al-Rāzī, label=none), () rather than ar, زکریاء, label=none (), as for example in , or in . In m ...
. Pollen was identified as the cause in 1859 by
Charles Blackley Charles Harrison Blackley (5 April 1820 – 4 September 1900) was the discoverer of the mechanism behind allergic rhinitis caused by pollen, commonly called hay fever. The isolation of hay fever as a condition had been known since 1819 through t ...
. In 1906 the mechanism was determined by
Clemens von Pirquet Clemens Peter Freiherr von Pirquet (12 May 187428 February 1929) was an Austrian scientist and pediatrician best known for his contributions to the fields of bacteriology and immunology. Career Born in Vienna, he studied theology at the Universit ...
. The link with hay came about due to an early (and incorrect) theory that the symptoms were brought about by the smell of new hay.


References


Further reading

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External links

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Types of Pollen Allergies
{{DEFAULTSORT:Allergic Rhinitis Allergology Steroid-responsive inflammatory conditions Type I hypersensitivity Wikipedia medicine articles ready to translate Wikipedia emergency medicine articles ready to translate