Clemastine and Perphenazine interaction
Clemastine and Perphenazine: 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 Perphenazine label · effective 2026-08-25
…contraindicated in comatose or greatly obtunded patients and in patients receiving large doses of central nervous system depressants (barbiturates, alcohol, narcotics, analgesics, or antihistamines); in the presence of existing blood dyscrasias, bone marrow depression, or liver damage; and in patients who have shown hypersensitivity to perphenazine products, their…
Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever and primary central nervous system (CNS) pathology.
From the Clemastine (Clemastine Fumarate) label · effective 2024-11-25
Use with CNS Depressants Clemastine has additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.). Use in Activities Requiring Mental Alertness Patients should be warned about engaging in activities requiring mental alertness such as driving a car or operating appliances, machinery, etc.
Drug Interactions Additive CNS depression may occur when antihistamines are administered concomitantly with other CNS depressants including barbiturates, tranquilizers, and alcohol.
Patients receiving antihistamines should be advised against the concurrent use of other CNS depressant drugs.
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.