This section covers allergy and intolerance, ingested (food), inhaled and contact. Please click on the aspect of the conditions that interests you in the left hand navigation bar.

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Allergy
The earliest definition of 'allergy' was an 'inappropriate response by the body to a perfectly harmless substance'.

In modern medical parlance, however, allergy has come to be more narrowly defined: a specific response by the immune system to a substance (inhaled, touched or eaten) which it mistakenly identifies as harmful.

Contact with this substance triggers the release of IgE antibodies which attach to 'mast' cells and, in turn, precipitate a release of histamine, the chemical which causes a contraction of the muscles around the air passages (an attack of breathlessness or asthma), local swelling and skin irritation, and, if the attack is serious enough, a drop in blood pressure.

Research is ongoing to find a way of preventing the immune system making these mis-identifications but until a breakthrough is achieved, the only treatment for allergy is avoidance of the allergen combined with the use of adrenaline (epinephrine) to countract the release of histamine in more serious attacks. See the articles under anaphylaxis.

Intolerance and sensitivity
Although the medical profession is very clear about what it means by allergy, the general population is a lot less so and use the term to cover any sort of adverse reaction to almost anything.

Many people certainly do suffer adverse reactions to substances, particularly foods, which have not sparked an immune system response. These responses are normally classed as intolerances or sensitivities and have a very wide range of causes, symptoms and degrees of severity. However, they nearly always manifest as part of (a result or symptom of) some other medical condition or illness.

Some conditions, such as coeliac disease or phenylketonuria are caused by specific foods or food components.

More frequently specific foods may be poorly tolerated because of some underlying condition. Thus IBS sufferers, find that specific foods trigger reactions; for sufferers from Crohn's specific foods irritate their condition; migraine sufferers may find that specific foods trigger attacks; some mental health conditions such as depression can be made better/worse by certain foods etc

The amount of the food needed to cause a reaction and the length of time it takes to do so will vary hugely. Moreover, in many cases, as the underlying health condition improves, so does the person's ability to tolerate a food which had previously upset them.

The articles in this section cover both allergies and intolerances. You wil also find allergy related articles in almost every other section.

NB Information on this site is not a substitute for medical advice and no liability can be assumed for its use.

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