Treatment of Allergic Rhinitis: Antihistamines or Corticosteroids?

The major early phase clinical manifestations of allergic rhinitis are mediated by mast cell-derived histamine. This is followed by an eosinophil-dominated inflammatory cell influx, allergic inflammation—leading to changes in sensory neurone function—and development of nasal hyper-responsiveness. Thus, there are two distinct targets for drug therapy: (1) inhibition of the early phase response by blockade of the effects of histamine with H1-antihistamines and (2) reduction of allergic inflammation by intranasal corticosteroids.

Looking first at the drugs, there are many safe and effective second-generation H1-antihistamines for the treatment of allergic rhinitis. As histamine is an important neurotransmitter in the brain, having a crucial arousal role in the circadian sleep/wake cycle and many other effects including stress management and the reinforcement of learning and memory, first-generation H1-antihistamines, which penetrate readily into the brain, have profound CNS effects and should be avoided. Also, there are several safe and effective intranasal corticosteroids, but preference should be given to those containing fluticasone or mometasone, which undergo rapid hepatic metabolism.

The ARIA guidelines (Bousquet J et al. Allergy 2008:63(Suppl. 86):8–160) are clear about the use of H1-antihistamines and corticosteroids. In mild, intermittent disease, where the histamine-mediated immediate response predominates, H1-antihistamines are recommended. As the disease becomes more prolonged or/and more severe and allergic inflammation becomes a major factor, corticosteroids become the drug of choice. It should be remembered that H1-antihistamines act rapidly, whereas corticosteroids take several days to become maximally effective. Both drugs should be given on a continuous basis.