TreatAllergies.com

The term "allergy" is derived from the Greek words allos, meaning other or changed, and ergon, which means action or reaction. It is estimated that approximately one in four people, or 25% of the population, in the United Kingdom suffers from an allergy at some point in their lives. Allergy describes the reaction produced when the body comes into contact with a normally harmless substance that the immune system remembers having been previously exposed to and mistakenly produces immunoglobulin E (IgE) antibody in response. Types of allergic disorders include:

• Asthma.
  
• Seasonal Rhinitis (Hayfever).
  
• Perennial Rhinitis (sufferers experience hayfever symptoms all-year-round).
  
• Urticaria ("hives").
  
• Acute Urticaria (a chronic but short-term urticaria lasting six weeks or more but not necessarily on a daily basis).
  
• Eczema (atopic dermatitis).
  
  Allergic rhinitis is an allergy that affects the nose and sinuses while asthma is an allergic reaction occurring in the chest and lungs. Allergic reactions in the skin are called urticaria ("hives") or angioedema (swelling). The immune system normally attacks the antigens that invade the body in order to protect the body but, in the case of allergies, this system malfunctions. When allergens enter the body they are mistakenly met by antibodies, which are released by white blood cells, or lymphocytes, manufactured in the bone marrow. The lymphocytes that produce antibodies are known as "B cells". When lymphocytes become activated some of them serve as "memory" cells. That is, they remember the antigens and are primed to deal with that specific type of invader again. This long-term memory is referred to as "acquired immunity" and is the basis of vaccinations. When you have an inherited tendency to develop allergies, your immune system mistakes benign foreign substances for dangerous one and prompts the antibodies into action unnecessarily.
  
  The main type of antibody produced is immunoglobulin E, known as IgE, and each allergen stimulates the production of a specific form of IgE to combat it. In allergy sufferers, IgE antibodies signal the release of chemicals, including histamine, upon contact with allergens. This triggers an allergic reaction, an immediate hypersensitive reaction often resulting in sneezing, a runny nose, itchy eyes, throat, and skin, and rashes.
  
  Most allergies are not dangerous and serve as more of an inconvenience or irritant in daily life. The exception is any allergy that can cause systemic anaphylaxis, which can be life-threatening. Some allergies can also trigger a serious asthma attack, with a tightening of the chest, wheezing, and difficulty breathing.
  
  While a person may have a genetic predisposition to developing allergies, an allergy will usually only develop after someone has specific contact with a particular type of allergen, such as ragweed or bee stings. If you live somewhere where pollen is not present then you would not develop hayfever. This explains why close relatives may share the same hypersensitivity but have different allergens that trigger their condition. It is believed to be possible, however, that an allergy can develop before birth, when foetus is exposed to an allergen while still in the womb.
  
  People with a genetic predisposition towards allergies are said to have a condition known as "atopy", from the Greek word atopos, meaning "out of place". Atopy tends to run in families and is an inherited attribute that makes a person more likely to develop an allergic disorder. It is believed that atopic people produce more IgE than others who do not share this condition. About a quarter to a third of the population are believed to have atopy but whether or not they actually go on to develop allergies depends on the environment that they are exposed to. So just because a parent has a especially bad allergy does not guarantee that their children will also suffer from any sort of allergy.
  
  It is estimated that there is a period in early childhood when a child is more susceptible to developing allergies. If they are exposed to allergens during the first three to six months of life, then it is more likely that they will develop an allergy later in life. Correspondingly, this theory maintains that if this period coincides with seasons when pollen is prevalent then a child's chances of getting hayfever are slightly raised.
  
  Another environmental factor that has an impact on the development of allergies is the number of siblings a child has. The reason for this is that when you have brothers and sisters you are exposed to more infections at an early age. Your immune system makes a lot of antibodies to combat common viruses and bacteria and this supersedes the creation of allergy antibodies.
  
  The statistics for "Westernised" societies suggests that allergies may be on the increase, especially amongst children. Some have blamed industrial and traffic pollution for this phenomenon, in Japan in particular, but it is still unclear exactly what sort of causal role pollution plays in the development of allergies. Pollution, however, does remain a common trigger for existing allergies.
  
  Allergic disorders are the body's response to a particular type of antigen called an allergen, which are benign to people who are not allergic to them. Common allergens can be found everywhere and include:
  
  Pollen is major source of allergies, especially ragweed, birch tree and cedar which cause hayfever.
  Milk, fruit, eggs, fish, and nuts are all common food allergies.
  Mould from plants and food are allergens likely to cause asthma.
  Venom from insects, including bee or wasp stings and mosquito bites.
  House dust, especially if it contains dust mite debris or animal dander (pieces of dry hair, fur or skin).
  Plant oils, especially poison ivy, or oak.
  Various other types of triggers include feathers, latex, wool, dyes, perfumes or cosmetics.
  In other cases, hot or cold temperatures, sunlight, and even certain emotional states, can act as allergens. People can also develop an allergy syndrome that links one type of allergy with another. For example, those with an allergy to latex are also more susceptible to developing an allergy to avocado, banana, chestnut or kiwifruit. Patients with untreated hayfever have been shown to be more likely to develop asthma.