Allergic rhinitis affects more than 35 million Americans, and intranasal corticosteroids are one of the most effective medical treatments currently available. Intranasal corticosteroids work by reducing inflammation and immune responses to allergens, substances such as pollen, dust mite particles and pet dander to which a person is sensitive. Long-term use of oral corticosteroids for controlling extremely severe asthma has been linked to an increased risk for ocular side effects, including cataracts. Oral corticosteroids can also be used to control severe allergic rhinitis and moderate to severe asthma exacerbations.

In this study, researchers examined medical records in the United Kingdom's General Practice Research Database, a national computerized database of patient records used for research. Researchers included 286,078 patient records in the study, of which 88,301 were intranasal corticosteroid users, 98,901 were oral corticosteroid users and 98,786 people that were not exposed to either form of corticosteroid. Researchers found 1,059 cases of cataracts, of which 217 were in the intranasal corticosteroid group, 629 were in the oral corticosteroid group and 213 were in the group unexposed to corticosteroids. The incidence rate of cataracts for the intranasal corticosteroid group and the unexposed group was 1.0 per 1,000 people. The incidence rate for the oral corticosteroid group was 2.2 per 1,000 people.

Researchers also compared the incidence rate of cataracts with the number of prescriptions a subject had received. For intranasal corticosteroid users, the incidence rate of cataracts did not increase significantly with increasing numbers of prescriptions. The incidence rate was 0.9 per 1,000 people for subjects with two to nine prescriptions. The rate was 1.0 per 1,000 people for people with ten or more prescriptions. Conversely, researchers found the risk of cataracts increased with an increasing number of oral corticosteroid prescriptions. For those with two to four prescriptions the incidence rate was 1.2 per 1,000 people. The incidence rate was 2.1 per 1,000 people for subjects with five to nine prescriptions. For those with ten or more prescriptions, the incidence rate for cataracts climbed to 4.6 per 1,000 people.

Researchers concluded that there was no increased risk of cataracts associated with the use of intranasal corticosteroids. By contrast, oral corticosteroid use was associated with an increased risk or cataracts. Researchers felt their results provided additional reassurance about the safety of prescribing intranasal corticosteroids for the treatment of allergic rhinitis.