Steroid nasal sprays rarely cause side-effects. This is because they are applied directly to the nose and very little of this medicine is absorbed into the body. Therefore, they are much less likely to cause side-effects in other parts of the body. Occasionally, they cause dryness, crusting, and bleeding of the nose. If this occurs, stop it for a few days and then restart. There have been reports of nasal steroids possibly having an effect on behaviour, particularly in children. This is thought to be rare. However, a few people have reported hyperactivity, problems sleeping, anxiety, depression, and aggression.
The precise mechanism through which fluticasone propionate affects rhinitis symptoms is not known. Corticosteroids have been shown to have a wide range of effects on multiple cell types (., mast cells, eosinophils, neutrophils, macrophages, lymphocytes) and mediators (., histamine, eicosanoids, leukotrienes, cytokines) involved in inflammation. In 7 trials in adults, Flonase Nasal Spray has decreased nasal mucosal eosinophils in 66% of patients (35% for placebo) and basophils in 39% of patients (28% for placebo). The direct relationship of these findings to long-term symptom relief is not known.