Chlorpromazine and Atenolol: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 15, 2026 · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Chlorpromazine
No brand names on recordAtenolol
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
You've been prescribed two medicines that can nudge each other to be a little stronger. Chlorpromazine calms the mind and can lower blood pressure, and atenolol slows the heart and lowers blood pressure. When taken together, each one can slow how the other is broken down, so their effects may stack up.
In real life, this could mean feeling extra dizzy or lightheaded, especially when standing up. This is based on theory and on what similar drug groups have done, so it isn't a sure thing. The good news is your care team can manage this easily by watching how you respond and adjusting a dose if needed.
Effect: Additive hypotension and possible enhanced phenothiazine effect from mutual inhibition of metabolism.
- Direction: Each agent may reduce clearance of the other, increasing exposure and pharmacodynamic effect of both. Neither is a prodrug.
- Mechanism: Bidirectional metabolic inhibition plus additive BP-lowering/CNS effects.
- Onset: Rapid.
- Evidence: Theoretical; extrapolated from phenothiazine/beta-blocker class data, not documented for this specific pair.
- Management: Monitor blood pressure, heart rate, and for excessive sedation or orthostasis. Reduce the dose of one or both if enhanced effects appear; individualize.
What happens
Hypotension and/or phenothiazine toxicity
Interaction Deep Dive
While this has not been documented specifically for the combination of chlorproMAZINE and atenolol, beta blocking agents and phenothiazine-related compounds have been shown to potentiate one another's effects123. The two drug classes can suppress each other's metabolism, resulting in additive effects from both agents.
Why it happens (mechanism)
Mutual inhibition of metabolism
How to manage this interaction
Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. This interaction is manageable with a little extra attention.
- Your care team may monitor you more closely, especially your blood pressure and heart rate.
- If either drug's effect becomes too strong, the dose may be adjusted and individualized by your team.
- Rise slowly from sitting or lying down to avoid dizziness.
- Tell your pharmacist or doctor if you feel unusually dizzy, faint, very drowsy, or notice a slow heartbeat.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Chlorpromazine and Atenolol together?
Taking chlorpromazine with atenolol may make both drugs stronger, mainly causing low blood pressure and dizziness; keep taking both as prescribed and let your care team monitor you and adjust a dose if needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chlorpromazine and Atenolol interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How is the Chlorpromazine and Atenolol interaction managed?
Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. This interaction is manageable with a little extra attention. Your care team may monitor you more closely, especially your blood pressure and heart rate. If either drug's effect becomes too strong, the dose may be adjusted and individualized by your team. Rise slowly from sitting or lying down to avoid diz… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Chlorpromazine or Atenolol need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (3)
- Peet M, Middlemiss SN, & Yates RA: Propranolol in schizophrenia. II. Clinical and biochemical aspects of combining propranolol with chlorpromazine. Br J Psychiatry 1981; 138:112-117. PubMed
- Vestal RE, Kornhauser DM, Hollifield JW, et al: Inhibition of propranolol metabolism by chlorpromazine. Clin Pharmacol Ther 1979; 25:19-24. PubMed
- Greendyke RM & Gulya A: Effect of pindolol administration on serum levels of thioridazine, haloperidol, phenytoin, and phenobarbital. J Clin Psychiatry 1988; 49:105-107.
Keep reading about Chlorpromazine
Keep reading about Atenolol
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