Hay fever

=allergic rhinoconjunctivitis due to seasonal triggers, typically grass and/or tree pollen. First described by John Bostock in 1819! More likely if born in early months of year!

So itchy, swollen, watery eyes, runny and/or blocked nose, sneezing. Often itchy throat and ears too. Cobble stone appearance can be seen at the back of throat.

Not dangerous, but can seriously affect quality of life: poor sleep, poor concentration (exams usually at worst time of year), embarrassment about snot. One study showed children in England were less likely to get their predicted exam grades if they had hay fever, especially if prescribed sedating antihistamines.

Associated with other atopic conditions, such as food allergy and asthma. Under recognized as trigger for asthma exacerbations – pollen is too large to trigger the lower airways directly, rather pollen exposure in the upper airways trigger inflammation that travels down over a period of weeks to the lower airways. An exception is when pollen grains are fragmented, as seen in thunder storm asthma [Australia, Clin Exp Allergy. 2018;48:1421‐1428]

There are many different species of grass, but if allergic to one you tend to be allergic to all of them. Trees on the other hand vary, you tend to be allergic to specific groups of trees. In Europe the most important are birch (northern Europe) and olive (Southern Europe). Birch is related to alder, hazel, beech and oak.  Olive is related to ash.  Weeds belong to various unrelated families.

Hazel trees can start producing pollen in February, weeds can continue produce pollen through September! Moulds seem more associated with asthma than hay fever. Cypress blooms in winter! 

It’s not just pollen count – the amount of allergen carried by the pollen varies too. Correlate pretty closely but varies by time and place. Pollen potency varies (4-5 fold difference) geographically, especially grass. France has the highest yearly average grass pollen potency, 7-fold higher than Portugal. Olive pollen from two locations 400km apart varied 4-fold in their allergen potency – in Portugal there are times when pollen from Spain probably more of a problem for triggering hay fever than pollen from “local” trees! [Health Impacts of Airborne Allergen Information Network (HIALINE project)]

Management

Watch the pollen count, and choose activities accordingly. Pollen levels fall in evening in countryside, but in cities not until 1am!

Closing windows, or at least not sitting near windows, washing hair, not drying clothes outside, pollen barrier balms.

Choose where you are going on holiday carefully!

Antihistamines – oral or nasal. Various, some people find one works better than another Sedating antihistamines eg Chlorphenamine should be avoided except at night. Nasal steroids useful if used correctly. Combination steroid/antihistamine available. Leukotriene receptor antagonist licensed for hay fever in children with asthma.

Short courses of oral steroids might be justified for special occasions.

Immunotherapy available – deaths reported in asthmatics with poor control.

Sublingual – age not important cf ability to hold in mouth for 2 minutes. Not approved by SMC in Scotland yet. Combined grass and house dust mite coming.

[Sian Ludman, St Mary’s]

For symptoms all year round (perennial), triggers such as house dust mite and pets are more likely.

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