The term ‘allergy’ is used only for the most extreme reactions on the spectrum of hypersensitivity.

For example, if your sinuses become blocked a few hours after you eat cheese, you can’t really say you’re ‘allergic’ to cheese.

Correct would be to say your body is somewhat ‘intolerant’ of cheese, or that you are ‘hypersensitive’ to cheese.

How does the allergic hay fever reaction work?

The early stages
As we know, in a war there are innocent bystanders who are affected. Hay fever is no different.

The allergic reaction in hay fever gives rise to casualties in special cells called mast cells, an injured one of which will immediately release into the bloodstream a cocktail of inflammatory chemicals such as histamine, tryptase, chymase, kinins and heparin.

Before long, additional chemicals such as leukotrienes and prostaglandin D2 flood the bloodstream, interact with the earlier ones, and within minutes give rise to irritation, itching, swelling and leak­age of fluid from the cells in the form of sneezing, a runny nose and watering eyes.

The latter stages
Within four to eight hours, the above-mentioned chemicals have worked hard to recruit further inflammatory substances, and this results in ongoing inflammation, often extending to wider-ranging mucous membranes.

The symptoms produced are similar to those of the early stage, except that there is less itching and sneezing and there is an increase in congestion and the creation of mucus.

The mixture of chemicals can even lead to muscle spasm, which causes tightening in the lungs and throat, as is experienced in asthma and laryngitis.

Fatigue, insomnia, irritability and a general feeling of malaise (feeling ‘out-of-sorts’) can arise from the late stage of reaction.

Accompanying these can be ultra-sensitivity to bright light (particularly sunlight) and loud noise, together with a lowered pain threshold.

This invariably has a negative impact on quality of life, at least for the duration of the symptoms.

Did you know: Up to 35% of the population can find themselves sneezing uncontrollably due to a sudden burst of sunlight? This phenomena known as PSR (the photic sneeze reflex) remains unexplained … though scientists have agreed on a detailed technical acronym for the condition that sufferers might prefer to use when describing their plight to an allergist – Autosomal-dominant Compelling Helio-Ophthalmic Outburst syndrome, or A.C.H.O.O. True story.

Additional environmental insults that can lead to or worsen hay fever with an allergic reaction of their own include bleach, cigarette smoke, dust mites, fungal spores, latex, mould, mushroom spores, nickel, perfume, vehicle pollution also called ‘petrochemical smog’.