Hay fever is a form of allergic rhinitis, and is often referred to as ‘seasonal allergic rhinitis’. Prevalence has dramatically increased over the last 20 years, with 10-25 per cent of adults and as many as 40 per cent of children affected. It is thought that improved living standards and reduced risk of childhood infections might increase children’s susceptibility to hay fever. Onset of symptoms is typically between the ages of 13-19 years old.
Pollen and fungal spores are the two major allergens that cause hay fever, with symptoms resulting from an antibody response to the allergen. IgE antibodies are activated that trigger the release of histamine and other chemical mediators (eg leukotrienes, kinins and prostaglandins) that give rise to the classic symptoms – nasal itching, sneezing (especially in repeated short bouts), watery rhinorrhoea and nasal congestion. People may also suffer from itching eyes, which leads to allergic conjunctivitis. Symptoms occur intermittently and tend to be worse in the morning and evening. Hay fever can affect people from as early as March (caused by tree pollens) all the way through to Autumn (fungal spores), although the majority of sufferers experience symptoms in the summer months of June and July (grass pollen).
Diagnosis with the classical symptom profile and seasonality should be straightforward. However, it is worth remembering that perennial allergic rhinitis needs to be ruled out. As its name suggests, the problem is persistent and does not exhibit seasonality. Key differences in symptom presentation are that nasal congestion is much more common and eye symptoms are rare.
Before starting medication it is important to try and minimise exposure to pollen. Patients should know when pollen counts will be high and try to avoid areas with high pollen counts, such as parks, gardens and fields. Secondly, they should make sure house windows are kept shut. Car pollen filters should be changed regularly and people should wear ‘wrap around’ sunglasses. Of course these measures will only go some way to reducing symptoms and most people will inevitably need medication. The range of current OTC medicines should control most people’s symptoms.
Systemic therapy: antihistamines
Both sedating and non-sedating antihistamines are clinically effective in reducing hay fever symptoms1. However, given the sedative effects of first generation antihistamines such as chlorphenamine they should not be routinely used. Therefore the pharmacist has a choice from acrivastine, cetirizine, or loratadine. All are equally effective, although none are truly non-sedating. Loratadine has been shown to cause the least sedation2 and on this basis should be considered drug of choice.
Options available OTC include antihistamines (azelastine), mast cell stabilisers (sodium cromoglicate) and steroids. Clinical trials have proven azelastine’s efficacy, and a meta-analysis concluded that it was more effective than placebo and equivalent to oral antihistamines3. Sodium cromoglicate has shown poor efficacy and its place in hay fever treatment is limited.
Intranasal corticosteroids are the medicine of choice for nasal congestion and are recommended by the World Health Organisation as first-line therapy. They have demonstrated superiority to antihistamines for all nasal symptoms, and equivalence for ocular symptoms4. Current OTC options include beclometasone, fluticasone and triamcinolone, although there is little difference in efficacy between the intranasal corticosteroids and clinical evidence does not support the use of one over another.
Treatment options are primarily limited to sodium cromoglicate. It has proven efficacy and is significantly better than placebo5. It does require four times a day dosing and compliance might be a problem. Sympathomimetics can be used to reduce ocular redness but should be restricted to shortterm use (less than five days) to avoid rebound effects.
Hay fever – summary
The best approach to pharmacological intervention is to first assess the severity of symptoms. Broadly speaking, hay fever is classified into mild intermittent general symptoms or moderate to severe intermittent symptoms. For mild general symptoms antihistamines are recommended. If this fails to control all symptoms then addition of eye drops or a corticosteroid nasal spray should be introduced to manage those symptoms not controlled. If a patient has moderate to severe intermittent symptoms then regular topical nasal corticosteroids should be first-line treatment, with antihistamines added if there is a poor response. Table 1 highlights some additional practical points when recommending treatment.
It is likely that the range of medicines to treat hay fever will grow over the next two to three years. Third generation antihistamines (eg levocetirizine, desloratadine and fexofenadine) are already available OTC in Australia, as are ketotifen and azelastine eye drops and ipratropium nasal spray.