Allergic rhinitis and asthma share various clinical, pathophysiological and immunological characteristics and often coexist. Recent studies provide evidence of cross-talk between both airway compartments, possibly by systemic signalling. These observations resulted in the concept of 'allergic airway disease', providing a rationale for systemic treatment. Presently, many novel systemic treatment modalities, including anti-IgE and phosphodiesterase-4 (PDE4) inhibitors, are being evaluated in clinical trials. In the Netherlands, there are currently two registered systemic therapies targeting the pathophysiological mechanisms of the united airway disease: leukotriene receptor antagonists and immunotherapy. These therapies are usually prescribed in combination with the standard pharmacotherapy.