Moderate
Loratadine × Morphine
Second-generation antihistamines×Natural opium alkaloids
Mechanism
Loratadine is a second-generation antihistamine with minimal blood-brain barrier penetration. With opioids, mild additive CNS depression is possible, especially in older patients.
Symptoms
Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.
Management
No dose adjustment needed. In older patients and palliative care, watch for sedation signs. Loratadine is preferred over cetirizine or chlorpheniramine on concurrent opioid therapy — minimal sedation. With marked sedation, stop the antihistamine.