Chlorpheniramine and Clonazepam interaction
Chlorpheniramine and Clonazepam: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Chlorpheniramine (Chlorphen-12) label · effective 2018-12-19
…have a breathing problem such as emphysema or chronic bronchitis glaucoma trouble urinating due to an enlarged prostate gland Ask a doctor or pharmacist before use if you are taking sedatives or tranquilizers When using this product excitability may occur, especially in children drowsiness may occur avoid alcoholic beverages alchohol, sedatives and tranquilizers…
From the Clonazepam (Klonopin) label · effective 2025-12-01
They should also be warned about the concomitant use of alcohol or other CNS-depressant drugs during Klonopin therapy (see PRECAUTIONS: Drug Interactions and PRECAUTIONS: Information for Patients ).
In a study in which the 2 mg clonazepam orally disintegrating tablet was administered with and without propantheline (an anticholinergic agent with multiple effects on the GI tract) to healthy volunteers, the AUC of clonazepam was 10% lower and the C max of clonazepam was 20% lower when the orally disintegrating tablet was given with propantheline compared to…
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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.