ModerateSecond-generation antihistamines×Natural opium alkaloids
Updated · Methodology
Mechanism
Cetirizine penetrates the blood-brain barrier at higher doses. With opioids, additive CNS depression and sedation occur.
Symptoms
Sedation, fatigue, slowed reactions, impaired coordination. In older patients: fall and fracture risk. Driving and operating machinery: accident risk.
Management
On the combination, cap cetirizine at 10 mg/day (at bedtime). Avoid the combination in older patients — fall risk. In palliative care, alternatives: loratadine (minimal sedation) or bilastine (minimal sedation and no sedating metabolites). With marked sedation, stop the antihistamine.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Tylenol 8 HR Arthritis Pain (acetaminophen) – label (2020)– ; DailyMed setid 3af22fc8-e4e0-4863-8696-6bc1257047cb