Allergic rhinitis antihistamines like azelastine antihistamine nasal spray, relief from symptoms is experienced within 15 minutes allowing for a more immediate 'as-needed' approach to dosage. There is not enough evidence of antihistamine efficacy as an add-on therapy with nasal steroids in the management of intermittent or persistent allergic rhinitis in children, so its adverse effects and additional costs must be considered. Ophthalmic antihistamines (such as azelastine in eye drop form and ketotifen) are used for conjunctivitis, while intranasal forms are used mainly for sneezing, rhinorrhea, and nasal pruritus. Antihistamine drugs can have undesirable side-effects, the most notable one being drowsiness in the
Rhinitis asthma developing later in life. Environmental irritants acts as modulators of airway inflammation in these contiguous airways. Development of occupational asthma is often preceded by occupational rhinitis. Among the causative agents are flours, enzymes used in processing food, latex, isocyanates, welding fumes, epoxy resins, and formaldehyde. Accordingly, prognosis of occupational asthma is contingent on early diagnosis and the adoption of protective measures for rhinitis. In the case of infectious rhinitis, vaccination against influenza viruses, adenoviruses, measles, rubella, "Streptococcus pneumoniae", "Haemophilus influenzae", diphtheria, "Bacillus anthracis", and "Bordetella pertussis" may help prevent it. The management of rhinitis depends on the underlying cause.