The pattern of disease in general varies widely and allergies are no different. It is extremely frustrating for sufferers because there is not one black or white answer or sole solution. We do know that children who develop an allergy can develop new allergies readily and have wide-ranging problems for most of their lives. On the other hand other people can be fine until adulthood and then develop symptoms of allergy for no apparent reason. The severity of reaction also varies greatly from individual to individual. The first time an allergen is encountered, it sets off a primary response from the immune system, to manufacture antibodies to it. No reaction will occur at this first meeting; it is not until the next encounter or often some time later if you have a particularly heavy exposure to something, that you will react. The reaction is the symptoms that you experience.
Allergy reactions or classic symptoms experienced by any individual can happen immediately, within a few hours or even days of encountering an allergen. A visible reaction may take up to four days to appear. If you are repeatedly in contact with an allergen, such as a commonly eaten food, i.e.: bread you may have continual symptoms which occasionally worsen. You can also get late or delayed reactions, resulting from the on-going chemical changes in your body. These can happen up to several days later in the case of reactions to food.
Most people who display symptoms of the classic allergy diseases (i.e. asthma, eczema, hay fever, urticaria, perennial rhinitis and anaphylactic shock) show raised levels of IgE in laboratory tests.
Once again this may not be true of everybody who suffers from these diseases. Generally speaking, if there is an identifiable trigger (such as pollen, food, or animal fur), and the patients display the classic symptoms of allergy, their illness will be diagnosed as allergy even if the tests are negative. Conversely, some people have a positive result to tests for allergens and raised IgE levels but do not actually react and show symptoms. It is not known why the body`s normal defence mechanism goes wrong in this way, although it is known that the tendency for it to happen runs in families and can be inherited. This inherited tendency is known as `atopy`. This means that if you or your partner suffer from allergy, your children are more likely to suffer from allergy, too, although they may well escape totally. If they do inherit the tendency, however, they will not necessarily inherit your precise symptoms or react to the same specific allergens. For example, you might have an allergy to cat fur and get asthma, but they might get perennial rhinitis from food allergy. This suggests that the fault in the immune system lies in the controlling or recognizing mechanisms. Many adults who have children diagnosed for food allergies find that they can identify symptoms in themselves they have suffered, sometimes for years not knowing.
Qualified diagnosis is highly recommended.