Hay fever is found throughout the world. Epidemiological evidence suggests considerable geographical variation in its prevalence. Symptoms are caused by an IgE-mediated type 1 hypersensitivity reaction to airborne allergens such as pollen or fungal spores, and may also cause eye, sinus, respiratory, and systemic problems.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for hay fever in adolescents and adults? We searched: Medline, Embase, The Cochrane Library, and other important databases up to April 2008 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
We found 211 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review we present information relating to the effectiveness and safety of the following interventions: intranasal corticosteroids, oral antihistamines, intranasal antihistamines, oral leukotriene receptor antagonists, systemic corticosteroids, intranasal ipratropium bromide, oral decongestants, and combinations of these treatments.
Hay fever causes sneezing, with an itchy, blocked, and/or running nose, and affects up to 25% of people in developed countries.
Symptoms are caused by an IgE-mediated type 1 hypersensitivity reaction to airborne allergens such as pollen or fungal spores, and may also cause eye, sinus, respiratory, and systemic problems.
Oral antihistamines reduce symptoms and improve quality of life compared with placebo, but they can cause drowsiness, particularly with older preparations.
CAUTION: astemizole and terfenadine may be associated with cardiac adverse effects.
Intranasal antihistamines improve symptoms compared with placebo. Intranasal azelastine seems as effective as oral antihistamines.We don't know whether oral decongestants reduce symptoms compared with placebo, but combined treatment with pseudoephedrine plus oral antihistamines may be more effective than either treatment alone.
Intranasal corticosteroids improve symptoms compared with placebo, are more effective at improving nasal symptoms, and appear to be equally effective at improving ocular symptoms compared with oral antihistamines.
Systemic corticosteroids improve symptoms compared with placebo, and are associated with mild adverse effects when used for short periods. Long-term or repeated use of systemic corticosteroids is associated with a range of well-documented, potentially serious adverse effects.
The oral leukotriene receptor antagonist montelukast improves symptoms and quality of life compared with placebo, but combination treatment with montelukast plus loratadine may be no more effective than either treatment alone.
We don't know whether intranasal ipratropium bromide reduces symptoms, as no studies were found.