Drug Interaction Report

Citalopram and Ketoconazole Topical: Interaction Details

A pharmacist-reviewed analysis of the Citalopram and Ketoconazole Topical interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Citalopram

Celexa
+

Ketoconazole Topical

Extina® Foam Ketozole® Cream Kuric Nizoral AD® Shampoo Nizoral® Cream Nizoral® Shampoo Xolegel®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 132 documented Citalopram interactions, 123 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
theoretical
Severity
Major

What happens

An increased risk of QT interval prolongation

Interaction Deep Dive

Coadministration of ketoconazole and a drug known to prolong the QT interval, such as citalopram may increase the risk for QT interval prolongation1. If coadministered, consider monitoring ECG. Do not exceed citalopram doses of 40 mg/day, and discontinue citalopram in patients who have persistent QTc measurements greater than 500 milliseconds. Ketoconazole is a potent inhibitor of CYP3A4 and may be expected to decrease the metabolism of citalopram. However, the concomitant administration of citalopram 40 mg and ketoconazole 200 mg decreased ketoconazole Cmax by 21% and AUC by 10%, but did not significantly affect the exposure of citalopram 2.

Why it happens (mechanism)

Additive QT interval prolongation

Literature reports

1 report — tap to read

a) In a drug interaction study, concomitant administration of citalopram 40 mg and ketoconazole 200 mg decreased ketoconazole Cmax by 21% and AUC by 10%, but did not significantly affect the exposure of citalopram 2.

Common questions

Can I take Citalopram and Ketoconazole Topical together?

An increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.

How serious is the Citalopram and Ketoconazole Topical 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 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 Citalopram or Ketoconazole Topical 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)

  1. Product Information: Ketoconazole oral tablet, ketoconazole oral tablet. Taro Pharmaceuticals U.S.A. Inc. (per DailyMed), Hawthorne, NY, 2024. DailyMed
  2. Product Information: CELEXA(R) oral tablets, citalopram oral tablets. Allergan USA Inc (per FDA), Madison, NJ, 2023. DailyMed
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Citalopram

Keep reading about Citalopram

All Citalopram interactions (132)
Also serious with: Linezolid Injection Metoclopramide Nasal Spray Metoclopramide Injection Palonosetron Injection
Ketoconazole Topical

Keep reading about Ketoconazole Topical

All Ketoconazole Topical interactions (546) Ketoconazole Topical drug information
Also serious with: Colchicine Conivaptan Crizotinib Dabrafenib
Beyond drug–drug

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:

Citalopram + Activated Charcoal Grapefruit Lithium St. John's Wort 5-htp Acacia Rigidula Acetyl-l-carnitine Adrafinil + 183 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.