What is Allergy: Definition and 16 Discussions

Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. 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 foods. Metals and other substances may also cause problems. Food, insect stings, and medications are common causes of severe reactions. Their development is due to both genetic and environmental factors. The underlying mechanism involves immunoglobulin E antibodies (IgE), part of the body's immune system, binding to an allergen and then to a receptor on mast cells or basophils where it triggers the release of inflammatory chemicals such as histamine. Diagnosis is typically based on a person's medical history. Further testing of the skin or blood may be useful in certain cases. Positive tests, however, may not mean there is a significant allergy to the substance in question.Early exposure to potential allergens may be protective. Treatments for allergies include the avoidance of known allergens and the use of medications such as steroids and antihistamines. In severe reactions injectable adrenaline (epinephrine) is recommended. Allergen immunotherapy, which gradually exposes people to larger and larger amounts of allergen, is useful for some types of allergies such as hay fever and reactions to insect bites. Its use in food allergies is unclear.Allergies are common. In the developed world, about 20% of people are affected by allergic rhinitis, about 6% of people have at least one food allergy, and about 20% have atopic dermatitis at some point in time. Depending on the country about 1–18% of people have asthma. Anaphylaxis occurs in between 0.05–2% of people. Rates of many allergic diseases appear to be increasing. The word "allergy" was first used by Clemens von Pirquet in 1906.

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  1. MidgetDwarf

    Question regarding Penicillin Allergy and Covid Vaccines

    Greetings. I have been contemplating getting the Covid Vaccine. However, I have a sever allergy to Penicillin. The last time I received penicillin, I was a young child. Difficulty breathing/hives, and went to the hospital. Anyways, I have been reading online to see if a Covid vaccine is safe...
  2. Wrichik Basu

    Gene for allergies and the common cold

    Some people are more susceptible to allergies and common cold than others. For example, my mother and I suffer from dust allergies and blocked nostrils throughout the year. In fact, last year or so, my mother had to be hospitalised as her lungs had become stiff due to sudden allergy. Almost...
  3. berkeman

    HEPA filters and air purifiers for allergy relief?

    My wife and some of my friends have been experiencing a spike in moderate allergy symptoms (Sx) this past week or two, and I was wondering if adding a HEPA air purifier at home in our bedroom would help. This recent PF thread discussed air purifiers, but not really from an allergy perspective...
  4. wolram

    Medical Peanut allergy -- What substance causes the reaction?

    What is in pea nuts that causes such violent illness and even death?
  5. Z

    Which of the symptoms is characteristic for food allergy

    Homework Statement Which of the symptoms is characteristic for food allergy bumps (pimple) on the face difficulty in breathing flue none of these Homework EquationsThe Attempt at a Solution I'm between the first and second.
  6. Z

    Which of the foods is more possible to cause allergy

    Homework Statement Which of the following foods is more possible to cause allergy apples stawberries cereals almonds Homework EquationsThe Attempt at a Solution I'm between almonds and strawberries
  7. R

    Bee Sting Immunity: Developing Tolerance & Immunity Questions

    Many years ago I was acutely allergic to bee stings. I was prescribed a "Epi" pen and used it several times. Eventually however, I noticed I had developed a tolerance to bee stings, and no longer carry my epi pen. Rather, I take a couple of Benytril and go on with my day. Does it make medical...
  8. A

    Does ethanol evaporate in dried food?

    I was wondering, if ethanol is used in a food, as it commonly is with food flavorings (as a solvent), and that food is then dried out such that It is made into a powder or cereal or something, does all the ethanol completely evaporate? I know ethanol is very volatile and has a low boiling...
  9. S

    My confusion with IgE antibodies and allergy?

    Hello everyone, There was a simple question given, where there was a bee sting on a guy and the question asked was what is the antibody involved. The answer is IgE. Now my question is when there is bee sting for the first time, why do we called it an allergic reaction. I mean for an allergy...
  10. Andre

    Allergy bomb ragweed banned in Holland

    It appears that common ragweed is the major cause of pollen allergy, for instance this study. The Netherlands has taken initiative to eradicate the American intruder in the local plant community. For instance (Dutch) Google translation of the first paragraph: So everybody is urged to...
  11. hypatia

    Medical Is Fall Bringing Worse Allergies?

    Last Thursday I was sitting in the back yard, and with in a 20 minute span, I was so congested, with really itchy eyes. I do have seasonal allergies, but never had them hit so fast, or so hard. We did have a odd summer, weather wise. Perhaps the ragweed plant decided to make extra pollen...
  12. B

    IGE Antibodies & Allergy Increase: Facts & Statistics

    How are IGE antibodies related to an increase of allergies in the world?
  13. L

    Medical How is allergy immunotherapy serum made?

    So I've been dedicating this year to my health, and I need to take care of my allergy problem. Does anyone know how the serum is made such that it's sterilized but doesn't harm the allergens? I can't find anything about it using google, and I'm not paying ridiculous amounts for something so...
  14. V

    Troublesome Allergy: Help for Seasonal Allergies

    I'm allergic to a large number of things including dust, some deos and perfumes, chalk powder, even vicks inhalers and lots of other things. I even get allergy attacks during change of seasons. This time it's been almost a week and my allegy is showing no signs of relenting. The old medicines...
  15. T

    Allergy: Anti-amthematical disease

    I have no clue of what is wrong with me. I had a chemistry test this Thursday and I had studied thoroughly two days before the test. When the day came, my brain completely knowcked out and I could not remember what I should do to solve the problems. Some of reasonings were successful because...
  16. Monique

    Peanut allergy vaccination

    This is already old news, but I was reminded of the issue today. I wonder: are you aware that researchers have devised a vaccination against peanuts? This therapy is used to desensitize people with a peanut allergy, I think it is pretty cool :)