Airborne food particles or droplets
Examples include egg applied by a spraying machine to glaze pies. Once sensitized, an individual may also react when they eat the same food.
Animal urine
Those working with laboratory animals are the most likely to be affected.
Vaccines
The use of eggs for culturing certain vaccines (eg influenza, measles-mumps-rubella) can lead to problems for those who are highly sensitive to eggs because a minute amount of egg protein persists in the purified vaccine.
Foods
Any food could, in theory, cause asthma. Other symptoms, such as pain in the abdomen, diarrhoea, eczema or rhinitis are likely if food is the cause. The reaction may occur rapidly in response to a small amount of the food, or may be delayed by several hours or even days, and require a large portion of the food. Some individuals have to eat the food for several days in succession before there is a response.
Foods can also cause rhinitis. In addition, hay-fever sufferers, especially those sensitive to birch pollen, may experience an itching mouth and swollen tongue after eating certain fruits or nuts. This is due to a cross-reaction between pollens and certain foods – see p296. Such symptoms may occur rapidly, but more often the rhinitis begins many hours after the food is eaten.
Yeasts
Alcoholic drinks, over-ripe fruits, breweries and bakeries are common sources, but see p191 for a full list. Mould and yeast sensitivity may sometimes be a sign of overpopulation by Candida.
Food additives
As for foods, although the response time is usually shorter. Colourings used in food may also be present in medicinal drugs, including antihistamine preparations.
Drugs
Antibiotics and aspirin are the common culprits but any drug, in theory, could provoke an allergic response. The highly sensitive individual may respond to trace amounts of antibiotic found in meat, eggs or milk.
Aspirin (salicylate) can trigger off asthma, and is sometimes the cause of nasal polyps, especially where these are accompanied by urticaria.
Paints, air-fresheners, aerosols, natural gas, fumes from cavity-wall insulation Many household chemicals produce vapour that may act either as an allergen (when combined with a protein) or as an irritant. They can contribute to both asthma and rhinitis. Air-fresheners are actually designed to fill the air with vapour – keeping the house clean and well-ventilated is a much better way of combating household smells.
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