Hayfever: Clearing the air

Learning objectives

After reading this feature you should be able to:

  • Explain the reasons for the rising prevalence of hayfever
  • Understand the concept of atopy and why some people and not others are affected by hayfever
  • Recommend suitable OTC treatment options.

 

The UK is one of the top three countries in the world for allergy incidence with hayfever affecting one in four of the population.1 This means that nearly 18 million Britons now suffer from hayfever – and numbers are continuing to rise sharply.1

According to two large population-based studies, the incidence of allergic sensitisation to airborne allergens such as pollen has increased by between 40 and 100 per cent over the past 15 years2, while the past year has seen a rise of over 10 per cent in the number of UK hospital admissions for patients with allergic rhinitis.3

Holly Shaw, nurse adviser at Allergy UK, says many factors underpin this increase in allergic conditions. “In previous centuries, we spent a majority of time outdoors, having constant exposure and contact with animals, trees, plants and soil, which provided an interaction between the microbes from the natural environment and those that naturally live on and in our bodies. This encouraged an efficient immune system that reacted appropriately to protect us from infection and disease.

“Without this interaction with the natural environment, and in those with a genetic predisposition, some people’s immune systems develop the tendency to react to normally harmless proteins like pollen, causing allergic reactions.

“Modern lifestyles result in people spending increasing amounts of time indoors. It is estimated that we spend over 90 per cent of our time/day inside the house, or in work and leisure environments that are hermetically sealed and poorly ventilated. Other factors include smaller family sizes, a greater increase in births by Caesarean section, increased exposure to pollution, overuse of antibiotics, and less healthy diets.”

Year-round problem

In addition to the growing number of hayfever sufferers, the hay fever season is showing signs of becoming a year-round problem. Currently, the season in the UK is broken down into three key sections to mirror the average pattern of release of the main allergenic pollens4:

  • Tree pollen: late March to mid-May
  • Grass pollen: mid-May to July
  • Weed pollen: end of June to September.

However, in reality, the pollen season can start as early as January and run until the end of November. Weed pollen and mould and fungal spores cause particular problems in the later autumn months. “In recent years, we have seen changes to seasons in the UK, with spring starting earlier and autumn ending later,” says Holly Shaw, “so for some people whose hay fever is triggered by more than one pollen, their symptoms may go on for an extended period.”

Some patients will also experience perennial rhinitis when hayfever symptoms occur year-round although, in most cases, this is triggered by an allergy to house dust mites rather than a specific pollen allergen.5

A key factor contributing to the extended hayfever season is climate change, with recent research published in the journal Nature Climate Change indicating that global warming is helping to fuel the spread of ragweed pollen across Europe.6 Based on computer modelling, it is predicted that this particularly potent airborne allergen will have invaded large areas of northern Europe, including the UK, by 2050, reaching concentrations some four times higher than they are now.6

Pollen from this invasive weed, native to North America, is capable of triggering severe allergic reactions in susceptible individuals and also has the unwanted effect of extending the hayfever season from summer through to the autumn.

Hayfever is also inextricably linked to pollution and, as a direct result of increased traffic pollution, is now twice as common in UK towns and cities as it is in the countryside. Rising pollution levels from vehicle exhaust fumes create a photochemical smog that traps pollen and prevents it from dispersing into the upper atmosphere.7 The net result is a concentration of airborne pollen allergens at ground level when air pollution levels are high.

Traffic pollution has a marked effect on hayfever in urban areas

Susceptibility

Hayfever occurs when the immune system triggers immunoglobulin E (IgE)-mediated inflammation of the nasal mucosa on exposure to pollen allergens in the air. Why pollen triggers an allergic reaction in some people and not others is unclear but is believed to be due to both genetic and environmental influences.

Proven risk factors for hayfever development include a family history of the condition, co-morbid allergic conditions such as asthma or eczema, reduced contact with infection, and exposure to tobacco smoke and diesel exhaust particles during childhood.5,8 Having eczema or asthma markedly increases the risk of developing hayfever – the three conditions are collectively known as the “atopic triad.”

Counting pollen

This year’s pollen count season began officially earlier this month, with hayfever symptoms usually starting to appear as soon as the pollen count exceeds 50.8 The pollen count refers to the number of grains of pollen in one cubic metre of air and is based on air samples collected in traps. Air is drawn into the traps and grains of pollen are collected on adhesive tape or glass plates before being counted. Samples are taken every two hours, with the formal pollen count based on an average of results over a 24-hour period.

With 30 different types of allergic pollen identified in the UK, daily information on the circulating levels of each one is key to helping hayfever sufferers manage and mitigate their symptoms.8

In the future, it is hoped that the UK pollen forecast will be able to use molecular genetics to identify which species, or combination of species of grass pollen, are linked to the worst allergic responses in hayfever sufferers. Such a move would provide more precise and shorter time points during which sufferers need to be cautious, together with more targeted information on when these are likely to occur.

“Being much more precise about which pollens are present in which areas, and when, will enable patients to better control their exposure to, and medication for, grass pollen,” says researcher Dr Nick Osborne.9

Managing symptoms

Despite the high number of hayfever sufferers in the UK, only one in five has ever consulted a GP about their condition, making pharmacies a key source of advice and support regarding symptom relief and lifestyle allergen avoidance measures.

Treatment options

Hay fever presents with typical seasonal symptoms including sneezing, nasal itching, nasal discharge and nasal blockage. Many sufferers also experience symptoms of allergic conjunctivitis, such as itching across both eyes, redness, swelling and watering.8,10

NICE Clinical Knowledge Summaries recommend antihistamines as first-line therapy for those seeking ‘as required’ treatment for occasional hayfever symptoms (the majority of pharmacy hayfever customers).10 For individuals suffering with allergic conjunctivitis, children aged over two years and anyone who prefers oral treatment, an oral antihistamine such as cetirizine, loratadine (preferred for pregnant/breast-feeding women) or fexofenadine (children over six years) can be recommended.10

For all other hayfever sufferers, intranasal azelastine is advocated as the first-choice antihistamine10 but a good technique is important to maximise the drug’s efficacy. Antihistamines can also be used as preventative treatments for hayfever – for example, taken before leaving the house on a day when the pollen count is forecast to be high.8,10

Corticosteroids exert an anti-inflammatory action that reduces swelling in the lining of the nose and can help to alleviate the full spectrum of hayfever symptoms. Most of the intranasal corticosteroid products currently available to treat hayfever have similar clinical efficacy but some (e.g. fluticasone, mometasone and budesonide) have the added convenience of once-daily dosing.8,10 Intranasal corticosteroids are generally recommended for patients with more persistent hayfever symptoms that fail to respond to antihistamines, sufferers whose main symptom is a blocked nose and women who are pregnant or breast-feeding.8

Nasal drops containing corticosteroids are also available. However, spray formulations are preferred based on their convenience of use, greater evidence base and lower systemic bioavailability.10 Pharmacy teams should advise customers that nasal corticosteroids are most effective if started a few weeks before the onset of hayfever symptoms and used regularly throughout the season.8

Nasal sprays containing decongestant ingredients (e.g. ephedrine or xylometazoline) are alternative treatments for the relief of nasal blockage associated with hayfever, but their use should be restricted to seven days due to the risk of rebound nasal congestion.8,10

Eye drops containing the antihistamines azelastine or olopatadine, or the mast cell stabiliser cromoglicate, can be recommended to specifically relieve the symptoms of allergic conjunctivitis often associated with hayfever.8,10

Key facts

  • Hayfever currently affects one in four of the UK population
  • Prevalence is rising rapidly, fuelled by key contributory factors such as climate change and pollution
  • In many cases hayfever symptoms can be effectively managed with pharmacy-led OTC treatment advice and lifestyle measures

 

References

  1. Allergy UK
  2. Warm K, Lindberg A et al. Increase in sensitization to common airborne allergens among adults – two population-based studies 15 years apart. Allergy, Asthma & Clinical Immunology 2013, 9:20
  3. Health and Social Care Information Centre (HSCIC). Provisional monthly topic of interest – allergies (2014)
  4. Met Office
  5. PatientPlus. Allergic rhinitis. Document 369 (v29) 2015.
  6. Hamaoui-Laguel L et al. Effects of climate change and seed dispersal on airbourne ragweed pollen loads in Europe. Nature Climate Change 2015; 5: 766-771
  7. Asthma UK
  8. NHS Choices. Hayfever
  9. Allergy UK. Research set to revolutionise pollen forecast. Press release October 2015. 
  10. NICE Clinical Knowledge Summaries. Allergic rhinitis. Revised October 2015



This website is for healthcare professionals, people who work in pharmacy and pharmacy students. By clicking into any content, you confirm this describes you and that you agree to British Pharmaceutical Students' Association's Terms of Use and Privacy Policy.

We use essential, performance, functional and advertising cookies to give you a better web experience. Find out how to manage these cookies here. We also use Interest Based Advertising Cookies to display relevant advertisements on this and other websites based on your viewing behaviour. By clicking "Accept" you agree to the use of these Cookies and our Cookie Policy.