Sertraline and Terfenadine: 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
Sertraline
No brand names on recordTerfenadine
No brand names on record
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.
These two medicines can each affect your heart's electrical rhythm in a way doctors call QT prolongation. Sertraline is an antidepressant, and terfenadine is an older antihistamine. When taken together, their effects on the heart rhythm can add up, which raises the risk of a serious, irregular heartbeat.
Because of this, using them together is considered something to avoid. The good news is your care team can manage this easily by choosing a safer combination. Please don't stop either medicine on your own. Just talk with your pharmacist or doctor, and they can sort out the safest option for you.
Effect: Additive QT interval prolongation with increased risk of serious ventricular arrhythmias (including torsades de pointes).
Mechanism: Both agents can prolong cardiac repolarization; combined use produces additive QT effects. This is a pharmacodynamic interaction, not primarily a metabolic one, so neither drug's prodrug status is relevant here.
- Direction: Additive risk (increased QT effect).
- Severity: Contraindicated.
- Evidence: Theoretical.
- Onset: Unspecified.
Management: Avoid concomitant use. If antihistamine therapy is needed, select a non-QT-prolonging alternative. Where any QT-active combination is unavoidable, correct electrolytes and monitor ECG/QTc.
What happens
An increased risk of QT interval prolongation
Interaction Deep Dive
Giving terfenadine together with medications known to lengthen the QT interval is contraindicated, since such combined administration can heighten the likelihood of QT prolongation as well as serious ventricular arrhythmias1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
What your care team may do:
- Because this combination is flagged as one to avoid, your prescriber will usually choose an alternative to one of the two drugs (often a different antihistamine).
- If both are ever needed, your team may check an ECG and keep an eye on electrolytes like potassium and magnesium.
What you should do:
- Keep taking your medicines as prescribed for now, and don't stop either one on your own.
- Contact your pharmacist or doctor to review this pairing.
- Seek prompt care if you feel fainting, palpitations, or a racing/irregular heartbeat.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Sertraline and Terfenadine together?
Sertraline and terfenadine can both stretch the heart's QT interval, and combining them is considered contraindicated. Talk to your pharmacist or doctor, who can safely swap one out. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Sertraline and Terfenadine interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Sertraline and Terfenadine interaction managed?
What your care team may do: Because this combination is flagged as one to avoid, your prescriber will usually choose an alternative to one of the two drugs (often a different antihistamine). If both are ever needed, your team may check an ECG and keep an eye on electrolytes like potassium and magnesium. What you should do: Keep taking your medicines as prescribed for now, and don't stop either one… 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 Sertraline or Terfenadine 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 (1)
- Product Information: Seldane(R), terfenadine. Marion Merrell Dow, Kansas City, MO, 1996.
Keep reading about Sertraline
Keep reading about Terfenadine
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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