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| Hay fever Classification & external resources | |
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| Pollen grains from a variety of common plants can cause hay fever. | |
| ICD-10 | J30.1 |
| ICD-9 | 477 |
| OMIM | 607154 |
| DiseasesDB | 31140 |
| MedlinePlus | 000813 |
| eMedicine | ent/194 med/104 ped/2560 |
| MeSH | D006255 |
For the play, see Hay Fever.
For the Bee Gees song, see Night Fever.
Allergic rhinitis, known as hay fever, is caused by pollens of specific seasonal plants and airborne chemicals and dust particles in people who are allergic to these substances. It is characterised by sneezing, runny nose and itching eyes. This seasonal allergic rhinitis is commonly known as \'hay fever\', because it is most prevalent during haying season. It is particularly prevalent from late May to the end of June (in the Northern Hemisphere). However it is possible to suffer from hayfever throughout the year.
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As noted above, hay fever involves an allergic reaction to pollen. A virtually identical reaction occurs with allergy to mold, animal dander, dust and similar inhaled allergens. Particulate matter in polluted air and chemicals such as chlorine and detergents, which can normally be tolerated, can greatly aggravate the condition.
The pollens that cause hay fever vary from person to person 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:
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.
When an allergen such as pollen or dust is inhaled by a person 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 from person to person. Very sensitive individuals can experience hives or other rashes.
Some disorders may be associated with allergies. These include eczema and asthma, among others.
Allergies are common. Heredity and environmental exposures may contribute to a predisposition to allergies.
The two categories of allergic rhinitis include:
The effect of hay fever can vary greatly: some people may only be mildly afflicted, whereas others may suffer greatly. Common symptoms include:
The history of the person\'s symptoms is important in diagnosing allergic rhinitis, including whether the symptoms vary according to time of day or the season, exposure to pets or other allergens, and diet changes.
Allergy testing may reveal the specific allergens the person is reacting 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.
Sufferers might also find that cross-reactivity occurs.Czaja-Bulsa G, Bachórska J (1998). "[Food allergy in children with pollinosis in the Western sea coast region]". Pol Merkur Lekarski 5 (30): 338-40. PMID 10101519. For example, someone allergic to birch pollen may also find that they have an allergic reaction to the skin of apples or potatoes.Yamamoto T, Asakura K, Shirasaki H, Himi T, Ogasawara H, Narita S, Kataura A (2005). "[Relationship between pollen allergy and oral allergy syndrome]". Nippon Jibiinkoka Gakkai Kaiho 108 (10): 971-9. PMID 16285612. 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.Malandain H (2003). "[Allergies associated with both food and pollen]". Allerg Immunol (Paris) 35 (7): 253-6. PMID 14626714. There are many cross-reacting substances.
Avoiding exposure to pollen is the best way to decrease allergic symptoms.The Facts about Hay Fever. Healthlink. University of Wisconsin. Retrieved on 2007-06-19.
The goal of treatment is to reduce allergy symptoms caused by the inflammation of affected tissues. The best "treatment" is to avoid what causes your allergic symptoms in the first place.
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This section does not cite any references or sources. (September 2007) Please improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed. |
The most appropriate medication depends on the type and severity of symptoms. Specific illnesses that are caused by allergies (such as asthma and eczema) may require other treatments.
Options include the following:
A large number of over-the-counter treatments are sold without FDA approval but are known for their positive effects, including herbs like eyebright (Euphrasia officinalis), nettle (Urtica dioica), and bayberry (Myrica cerifera), which have not been shown to reduce the symptoms of nasal-pharynx congestion. In addition, feverfew (Tanacetum parthenium) and turmeric (Curcuma longa) has been shown to inhibit phospholipase A2, the enzyme which releases the inflammatory precursor arachidonic acid from the bi-layer membrane of mast cells (the main cells which respond to respiratory allergens and lead to inflammation) but this is only in test tubes and it is not established as antiinflammatory in humans.
Allergen immunotherapy is commonly used in patients suffering from allergic rhinitis, allergic asthma, or life threatening stinging insect allergy. This type of therapy has been found to potentially alter the course of all three of the above disorders. Allergen immunotherapy provides long-term relief of the symptoms associated with rhinitis and asthma.
It has been claimed that homeopathy provides relief free of side-effects. However, this is strongly disputed by the medical profession on the grounds that there is no valid evidence to support this claim.Susan O\'Meara, Paul Wilson, Chris Bridle, Jos Kleijnen and Kath Wright (2002). Effective Health Care: Homeopathy (PDF). NHS Centre for Reviews and Dissemination. Retrieved on 2007-06-10. “There are currently insufficient data ... to recommend homeopathy as a treatment for any specific condition” The list of suggested medication includes
Therapeutic efficacy of complementary-alternative treatments for rhinitis and asthma is not supported by currently available evidence.Passalacqua G, Bousquet PJ, Carlsen KH, Kemp J, Lockey RF, Niggemann B, Pawankar R, Price D, Bousquet J (2006). "ARIA update: I--Systematic review of complementary and alternative medicine for rhinitis and asthma". J. Allergy Clin. Immunol. 117 (5): 1054-62. PMID 16675332. Terr A (2004). "Unproven and controversial forms of immunotherapy.". Clin Allergy Immunol. 18 (1): 703-10. PMID 15042943.
Nevertheless, there have been some attempts with controlled trialsWorld Health Organisation (2002). Acupuncture: Review and Analysis of Reports on Controlled Clinical Trials, 87. ISBN 9789241545433. to show that acupuncture is more effective than antihistamine drugs in treatment of hay fever. Complementary-alternative medicines such as acupuncture are extensively offered in the treatment of allergic rhinitis by non-physicians but evidence-based recommendations are lacking. The methodology of clinical trials with complementary-alternative medicine is frequently inadequate. Meta-analyses provides no clear evidence for the efficacy of acupuncture in rhinitis (or asthma). It is not possible to provide evidence-based recommendations for acupuncture or homeopathy in the treatment of allergic rhinitis.
Eating locally produced unfiltered honey is believed by many to be a treatment for hayfever, supposedly by introducing manageable amounts of pollen to the body. Clinical studies have not provided any evidence for this belief.
TV Rajan, H Tennen, RL Lindquist, L Cohen, J Clive (February 2002). "Effect of ingestion of honey on symptoms of rhinoconjunctivitis" (in English). Annals of allergy, asthma & immunology 88 (2): 198-203. ISSN 1081-1206. PMID 11868925. Retrieved on 2007-06-19. “This study does not confirm the widely held belief that honey relieves the symptoms of allergic rhinoconjunctivitis”
Most symptoms of allergic rhinitis can be readily treated.
In some cases (particularly in children), people may outgrow an allergy as the immune system becomes less sensitive to the allergen. However, as a general rule, once a substance causes allergies for an individual, it can continue to affect the person over the long term.
More severe cases of allergic rhinitis require immunotherapy (allergy shots) or removal of tissue in the nose (e.g., nasal polyps) or sinuses.
A case-control study found "symptomatic allergic rhinitis and rhinitis medication use are associated with a significantly increased risk of unexpectedly dropping a grade in summer examinations".Walker S, Khan-Wasti S, Fletcher M, Cullinan P, Harris J, Sheikh A (2007). "Seasonal allergic rhinitis is associated with a detrimental effect on examination performance in United Kingdom teenagers: case-control study". J. Allergy Clin. Immunol. 120 (2): 381-7. doi:10.1016/j.jaci.2007.03.034. PMID 17560637.
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