Promethazine and Scopolamine interaction
Promethazine and Scopolamine: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Promethazine (PROMETHAZINE HYDROCHLORIDE) label · effective 2026-04-16
The impairment may be amplified by concomitant use of other central-nervous-system depressants such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore such agents should either be eliminated or given in reduced dosage in the presence of promethazine…
Drug Interactions CNS Depressants Promethazine Syrup may increase, prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore, such agents should be avoided or administered…
CNS Depressants Promethazine Syrup may increase, prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore, such agents should be avoided or administered in reduced…
From the Scopolamine (Transderm Scop) label · effective 2025-06-10
• Gastrointestinal and Urinary Disorders : Consider more frequent monitoring during treatment in patients suspected of having intestinal obstruction; patients with pyloric obstruction, patients with impeded urine flow or receiving other anticholinergic drugs.
Concomitant use of other drugs that cause central nervous system (CNS) adverse reactions (e.g., alcohol, sedatives, hypnotics, opiates, and anxiolytics) or have anticholinergic properties (e.g., other belladonna alkaloids, sedating antihistamines, meclizine, tricyclic antidepressants, and muscle relaxants) may increase this effect [see Drug Interactions ( 7.1 )] .
Consider more frequent monitoring during treatment with TRANSDERM SCŌP in patients suspected of having intestinal obstruction, patients with pyloric obstruction or patients with impeded flow of urine (e.g., in diseases of the prostate or urinary bladder neck obstruction) and patients receiving other anticholinergic drugs [see Drug Interactions ( 7.2 )] .
…adverse reactions of drowsiness, dizziness or disorientation (e.g., sedatives, hypnotics, opiates, anxiolytics and alcohol) or have anticholinergic properties (e.g., other belladonna alkaloids, sedating antihistamines, meclizine, tricyclic antidepressants, and muscle relaxants) may potentiate the effects of TRANSDERM SCŌP [see Warnings and Precautions ( 5.2 )] .
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.