Amitriptyline and Brompheniramine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amitriptyline
Brompheniramine
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.
What's going on: Amitriptyline (Elavil) and brompheniramine (found in Respa-BR) can both nudge up serotonin, a chemical messenger in your body. When two medicines raise serotonin at the same time, there's a small chance levels climb too high, which is called serotonin syndrome.
Signs to watch for include feeling agitated or confused, a fast heartbeat, sweating, shivering, muscle twitching or stiffness, and a fever. This is uncommon and the concern here is mostly theoretical, but it's worth knowing. The good news is your care team can manage this by watching you closely. Don't stop either medicine on your own. Just check in with your pharmacist or doctor.
Interaction: Additive serotonergic effects with concurrent amitriptyline (a TCA with serotonin reuptake inhibition) and brompheniramine (an antihistamine with weak serotonergic activity), theoretically increasing serotonin syndrome risk. Neither agent is bioactivated in a way that reverses this direction; the effect is additive/pharmacodynamic, not a metabolic (PK) interaction.
- Direction: increased serotonergic tone
- Evidence: theoretical; onset unspecified
- Severity: major (serotonin syndrome can be life-threatening)
- Monitor for: neuromuscular abnormalities (clonus, hyperreflexia, tremor, rigidity), autonomic hyperactivity (tachycardia, hyperthermia, diaphoresis, mydriasis), and mental status changes.
If symptoms emerge, discontinue offending agents and provide supportive care.
What happens
An increased risk of serotonin syndrome (hypertension, hyperthermia, myoclonus, mental status changes)
Interaction Deep Dive
Amitriptyline, which acts as a serotonin reuptake inhibitor2, and brompheniramine both influence serotonergic neurotransmitter systems. Because their serotonergic effects are additive and may heighten the likelihood of serotonin syndrome, caution is advised when the two are taken together. When amitriptyline and brompheniramine are given at the same time, it may be appropriate to watch for the signs and symptoms of serotonin syndrome throughout treatment. Such symptoms encompass neuromuscular abnormalities (for example, hyperreflexia, tremor, muscle rigidity, clonus, peripheral hypertonicity, and shivering), autonomic hyperactivity (for example, tachycardia, mydriasis, diaphoresis, and diarrhea), and alterations in mental status (for example, agitation and delirium). This condition has the potential to be life-threatening. Should serotonin syndrome occur, stop the responsible agents and administer supportive care along with any other therapy that may be needed 1.
Why it happens (mechanism)
Additive serotonergic effect
How to manage this interaction
If both are prescribed, keep taking them as directed unless your prescriber tells you otherwise. This combination can usually be used with care.
- Your care team may monitor you more closely for signs of serotonin syndrome, especially when starting or increasing a dose.
- Doses may be adjusted and individualized by your team if needed.
- Tell your pharmacist or doctor about all other serotonergic products, including cold and allergy remedies, that also contain brompheniramine.
Seek urgent care if you notice agitation, confusion, fever, sweating, a racing heart, shivering, or muscle twitching or stiffness.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Amitriptyline and Brompheniramine together?
Using amitriptyline and brompheniramine together can slightly raise the theoretical risk of serotonin syndrome, so keep taking both as prescribed and watch for agitation, fever, sweating, fast heartbeat, or muscle twitching, and get help if they appear. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amitriptyline and Brompheniramine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Amitriptyline and Brompheniramine interaction managed?
If both are prescribed, keep taking them as directed unless your prescriber tells you otherwise. This combination can usually be used with care. Your care team may monitor you more closely for signs of serotonin syndrome, especially when starting or increasing a dose. Doses may be adjusted and individualized by your team if needed. Tell your pharmacist or doctor about all other serotonergic produc… 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Amitriptyline or Brompheniramine 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 a safer alternative to one of these medications for me?
References (2)
Keep reading about Amitriptyline
Keep reading about Brompheniramine
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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