In many cases diagnosis of AR will be based on the history and clinical features alone, and the patient will be aware of the diagnosis. Many people with the condition never undergo formal screening (e.g. skin prick testing).

A diagnosis of AR should be suspected if there are typical clinical features – sneezing, nasal itching, rhinorrhoea (runny nose and/or post-nasal drip), and nasal obstruction. Nasal secretions are usually clear; yellow-green secretions occur if the cause is infectious (e.g. viral). Nasal obstruction can be partial or complete and usually affects both sides. A history of recent exposure to grass pollen, animal dander or house dust mites helps to confirm the picture. A family history of atopy makes the diagnosis of AR even more likely but a number of non-allergic triggers (e.g. viral infections, drugs, occupational irritants, smoke and air pollution) can induce nasal symptoms that mimic AR.

In popular parlance the terms ‘allergy’ and ‘irritation’ are often used interchangeably but it is important to distinguish between the two because the management of allergic responses differs from that of irritant responses. For example, irritant rhinitis caused by frequent exposure to chlorine (in swimming pools) can be managed by avoiding swimming in heavily chlorinated water, whereas allergen avoidance can be more difficult. Some drugs can make symptoms of AR worse (e.g. alpha-blockers, beta-blockers, ACE inhibitors, chlorpromazine, aspirin, NSAIDs, oral contraceptives and cocaine). Rebound nasal congestion can occur when stopping prolonged treatment with intranasal decongestants due to rebound vasodilation (so-called ‘rhinitis medicamentosa’).