<unk> , of which the seasonal type is called hay fever, is a type of inflammation in the nose that occurs when the immune system overreacts to allergens in the air. Signs and symptoms include a runny or stuffy nose, sneezing, red, itchy, and watery eyes, and swelling<unk> ound 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<unk>  also have asthma,<unk>  conjunctivitis, or atopic dermatitis.<unk>  is typically triggered by environmental allergens such as pollen, pet hair, dust, or mold. Inherited genetics and environmental exposures contribute to the development of<unk> s. 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. 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 or blood tests for allergen-specific IgE antibodies.These tests, however, can be falsely positive. The symptoms of<unk> s resemble those of the common cold; however, they often last for more than two weeks and typically do not include a fever. Exposure to animals early in life might reduce the risk of developing these specific<unk> s. Several different types of medications reduce<unk>  symptoms, including nasal steroids, antihistamines, such as diphenhydramine, cromolyn sodium, and leukotriene receptor antagonists 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 (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.<unk>  is the type of allergy that affects the greatest number of people. In Western countries, between 10 and 30% of people<unk> e 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 Rhazes. In 1859, Charles Blackley identified pollen as the cause. In 1906, the mechanism was determined by Clemens von Pirquet. 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.
Allergic rhinitis
Common cold
Nonallergic rhinitis
Honeymoon rhinitis
Aerosinusitis
Rhinosinusitis
Chronic atrophic rhinitis
Inclusion body rhinitis