0_Wizard
Allergies are so fascinating to me, especially considering that they are actually allergic diseases. 
Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity of the immune system to something in the environment that usually causes little or no problem in most people.
chosen_Allergy_0
Allergy
chosen_topic_0_Allergy
Allergy
Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity of the immune system to something in the environment that usually causes little or no problem in most people. These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis. Symptoms may include red eyes, an itchy rash, sneezing, a runny nose, shortness of breath, or swelling. Food intolerances and food poisoning are separate conditions. Common allergens include pollen and certain food. Metals and other substances may also cause problems. Food, insect stings, and medications are common causes of severe reactions.
Omalizumab
Omalizumab, sold under the trade name Xolair, is a medication originally designed to reduce sensitivity to allergens. It has been used to try to control severe allergic asthma, which does not respond to high doses of corticosteroids. It has been approved for treating people 12 years and older with severe or moderate to severe allergic asthma in more than 90 countries, since its first of such approval in 2002 in Australia. Omalizumab was approved in March 2014 in the European Union and the U.S.A. and in about 10 other countries for treating patients 12 years and above with chronic spontaneous urticaria (CSU) (also referred to as chronic idiopathic urticaria or CIU), which cannot be treated with H1-antihistamines.
Hygiene hypothesis
In medicine, the hygiene hypothesis is a hypothesis that states a lack of early childhood exposure to infectious agents, symbiotic microorganisms (such as the gut flora or probiotics), and parasites increases susceptibility to allergic diseases by suppressing the natural development of the immune system. In particular, the lack of exposure is thought to lead to defects in the establishment of immune tolerance. The hygiene hypothesis has also been called the "biome depletion theory" and the "lost friends theory". The original formulation of the hygiene hypothesis dates from 1989 when David Strachan proposed that lower incidence of infection in early childhood could be an explanation for the rapid 20th century rise in allergic diseases such as asthma and hay fever.
Food allergy
A food allergy is an abnormal immune response to food. The signs and symptoms may range from mild to severe. They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressure. This typically occurs within minutes to several hours of exposure. When the symptoms are severe, it is known as anaphylaxis. Food intolerance and food poisoning are separate conditions. Common foods involved include cow's milk, peanuts, eggs, shellfish, fish, tree nuts, soy, wheat, rice, and fruit. The common allergies vary depending on the country. Risk factors include a family history of allergies, vitamin D deficiency, obesity, and high levels of cleanliness.
Allergic conjunctivitis
Allergic conjunctivitis 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 to vasodilation of the peripheral small blood vessels), edema (swelling) of the conjunctiva, itching, and increased lacrimation (production of tears). If this is combined with rhinitis, the condition is termed allergic rhinoconjunctivitis. The symptoms are due to release of histamine and other active substances by mast cells, which stimulate dilation of blood vessels, irritate nerve endings, and increase secretion of tears.
Milk allergy
Milk allergy is an adverse immune reaction to one or more of the protein constituents of cow's milk. Symptoms can be rapid or gradual in onset. The former may include anaphylaxis, a potentially life-threatening condition which requires treatment with epinephrine. The latter can take hours to days to appear. Presentations may include atopic dermatitis, inflammation of the esophagus, enteropathy involving the small intestine and proctocolitis involving the rectum and colon. Management is by avoiding eating any food that contains dairy. Exposure to low levels of milk proteins is a health risk. In people with IgE-mediated food allergy the individual threshold dose capable of provoking an allergic reaction can vary widely, but is in a low milligram range.
Peanut allergy
Peanut allergy is a type of food allergy to peanuts. It is different from nut allergies. Physical symptoms of allergic reaction can include itchiness, urticaria, swelling, eczema, sneezing, asthma, abdominal pain, drop in blood pressure, diarrhea, and cardiac arrest. Anaphylaxis may occur. It is due to a type I hypersensitivity reaction of the immune system in susceptible individuals. The allergy is recognized "as one of the most severe food allergies due to its prevalence, persistency, and potential severity of allergic reaction." Prevention may be partly achieved through early introduction of peanuts to the diets of pregnant women and babies.
1_Apprentice
I agree and have always been confused as to how they happen. What causes allergies?