The desired response is easier nasal breathing with no clinically significant systemic change. Mild dryness, transient jitteriness, or difficulty sleeping may occur with adrenergic therapy; insomnia is the most commonly reported adverse effect in adult evidence. A rising blood pressure, marked tachycardia, persistent palpitations, chest pain, or severe agitation is not a therapeutic response. Ask how long a topical spray has been used. Frequent or prolonged use can cause rhinitis medicamentosa, in which the nasal mucosa becomes congested again—or more congested—because of the medication. Rebound may appear as early as day 3 or 4, although timing varies. A history of prior rhinitis medicamentosa matters because relapse can occur rapidly after re-exposure. The practical safety limit for topical nasal vasoconstrictors is no more than 3 consecutive days unless a clinician is directing a different plan. Increasing the number of sprays or switching from one topical vasoconstrictor to another does not solve rebound physiology. Pseudoephedrine also has rare neurologic safety signals. Sudden severe or “thunderclap” headache, vomiting, confusion, seizure, or visual disturbance may indicate posterior reversible encephalopathy syndrome or reversible cerebral vasoconstriction...