Side effects of overusing decongestant nasal sprays include nasal passage damage and lack of bodily response to the decongestant's effects, a condition known as rhinitis medicamentosa, according to WebMD. Overusing nasal sprays can also lead to inaccurate diagnoses of the conditions causing nasal inflammation.
Rhinitis medicamentosa generally occurs after a patient uses a decongestant nasal spray repeatedly for a period of between three and five consecutive days, according to WebMD. This condition can occur whether using over-the-counter nasal sprays, steroid sprays, antihistamines or even saline solutions.
Other possible side effects of nasal spray overuse include increased risk of sinus infection, frequent headaches, coughing, congestion and septal perforation, a rare side effect of nasal spray overuse that occurs when a tear develops in the membrane that divides the nostrils, notes WebMD.
Powerful, longer-lasting nasal spray products can help reduce patients' incentives to overuse the products. Examples include anti-inflammatory nasal corticosteroids that typically provide relief lasting for an entire day. A single dose of a nasal antihistamine spray, by comparison, generally lasts for 12 hours. WebMD suggests that despite the existence of alternatives to nasal sprays, the only effective way to prevent complications arising from their overuse is to abstain from them for a period of time.