Fluconazole and Amitriptyline: 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
Fluconazole
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.
If you take amitriptyline (Elavil) for mood, sleep, or nerve pain, and your doctor prescribes fluconazole (Diflucan) for a fungal or yeast infection, these two can interact. Fluconazole slows down how your body breaks down amitriptyline, so the amitriptyline can build up higher than usual. That can mean more side effects like drowsiness, dry mouth, dizziness, and confusion. More importantly, both drugs can affect your heart's rhythm, and together they raise that risk a bit more.
The good news is this is very manageable. Your care team can check your amitriptyline levels and adjust your dose if needed. Keep taking both as prescribed and just let your pharmacist or doctor know you are on both.
Effect: Increased amitriptyline exposure with risk of TCA toxicity and additive QT prolongation (torsades de pointes, cardiac arrest).
- Mechanism: Fluconazole is a CYP inhibitor (notably CYP2C19 and CYP3A4, contributors to amitriptyline metabolism), raising amitriptyline concentrations; plus additive QTc-prolonging effect. Amitriptyline is active drug, not a prodrug, so inhibition increases effect.
- Onset: Delayed. Evidence: Probable (case reports). Severity: Major.
- Management: If coadministration is required, measure S-amitriptyline levels before starting fluconazole and repeat at 1 week; adjust amitriptyline dose accordingly. Consider baseline/follow-up ECG and monitor for anticholinergic/sedative toxicity and electrolytes.
What happens
Increased amitriptyline exposure, an increased risk of amitriptyline toxicity and an increased risk of cardiotoxicity (QT interval prolongation, torsades de pointes, cardiac arrest)
Interaction Deep Dive
Taking fluconazole together with amitriptyline can enhance the effects of amitriptyline1. A number of case reports have documented elevated amitriptyline levels along with indications of toxicity, such as QT prolongation and torsades de pointes, when the two drugs were given concurrently234. When combined use cannot be avoided, obtain S-amitriptyline levels before starting the combination and again after 1 week. Modify the amitriptyline dose as needed1.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
This combination can be used when needed, but your care team will usually take extra steps to keep you safe:
- They may check your amitriptyline blood level before you start fluconazole and again about one week later.
- Your amitriptyline dose may need to be adjusted and individualized based on those results.
- Because both drugs can affect heart rhythm, your team may monitor you more closely, possibly with an ECG.
Keep taking both medications as prescribed. Tell your pharmacist or doctor you are on both, and report new drowsiness, confusion, fast or irregular heartbeat, fainting, or dizziness right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
3 reports — tap to read
a) Three case reports document elevated amitriptyline concentrations when combined with fluconazole. Patient 1, a 39-year-old male, was receiving fluconazole 200 mg daily along with amitriptyline 25 mg three times daily. Three days after the amitriptyline dose was raised to 50 mg three times daily for neuropathic pain, the patient developed visual hallucinations and showed a serum amitriptyline concentration of 724 ng/mL (therapeutic range, 150 ng/mL to 250 ng/mL). Patient 2, a 35-year-old male, was on amitriptyline 50 mg per day. Following the addition of fluconazole 100 mg daily after a 200 mg loading dose, the patient's serum amitriptyline level reached 349 ng/mL on day 33 of the combined regimen. No behavioral changes were noted in this patient. Patient 3, a 43-year-old male with end-stage renal disease, had been on amitriptyline 100 mg per day for more than a year. After receiving fluconazole 200 mg to 400 mg daily for five days following a 1000 mg loading dose, his serum amitriptyline concentration measured 1224 ng/mL. The patient suffered a cardiac arrest eight days afterward and died following a complicated hospital course. In each of these cases, patients were receiving several additional ongoing medications. The authors propose that adding fluconazole led to the increases in serum amitriptyline, potentially through fluconazole-mediated inhibition of cytochrome P450 isozymes 3.
b) A 57-year-old female came to an emergency department reporting multiple episodes of losing consciousness, each occurring while she was seated. Chest pressure followed each episode. Her medications comprised amitriptyline over the preceding five weeks, sertraline 100 mg daily over the preceding seven months, fluconazole, lisinopril, and an iron supplement. An electrocardiogram (ECG) taken three months before presentation demonstrated a normal sinus rhythm with a normal QT interval. After admission to the hospital, the patient had several episodes of torsades de pointes captured in leads II and VI accompanied by near syncope while she was supine. Amitriptyline was stopped and fluconazole was decreased to 200 mg daily. Subsequent ECGs revealed gradual normalization of the QT interval, and ECGs obtained three and six months after hospitalization were normal 5.
c) A 12-year-old boy with prostatic rhabdomyosarcoma had transient loss of consciousness linked to simultaneous fluconazole and amitriptyline therapy. The syncopal episodes recurred intermittently over roughly seven months and corresponded with the introduction of fluconazole to his medication regimen, which already included amitriptyline. The patient had previously tolerated each drug when administered alone. He had no further syncopal episodes once amitriptyline was discontinued 2.
Common questions
Can I take Fluconazole and Amitriptyline together?
Fluconazole can raise amitriptyline levels and add to heart-rhythm risk, so your care team may check amitriptyline levels and adjust the dose. Keep taking both as prescribed and report any dizziness, fainting, or irregular heartbeat. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fluconazole and Amitriptyline interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How is the Fluconazole and Amitriptyline interaction managed?
This combination can be used when needed, but your care team will usually take extra steps to keep you safe: They may check your amitriptyline blood level before you start fluconazole and again about one week later. Your amitriptyline dose may need to be adjusted and individualized based on those results. Because both drugs can affect heart rhythm, your team may monitor you more closely, possibly… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Fluconazole or Amitriptyline 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 (5)
- Product Information: DIFLUCAN(R) oral tablets, suspension, fluconazole oral tablets, suspension. Roerig (per FDA), New York, NY, 2023. DailyMed
- Robinson R, Nahata M, & Olshefski R: Syncope associated with concurrent amitriptyline and fluconazole therapy. Ann Pharmacother 2000; 34:1406-1409. PubMed
- Newberry DL, Bass SN, & Mbanefo CO: A fluconazole/amitriptyline drug interaction in three male adults. Clin Infect Dis 1997; 24:270-271. PubMed
- Khazan M & Mathis AS: Probable cause of torsades de pointes induced by fluconazole. Pharmacotherapy 2002; 22(12):1632-1637.
- Dorsey ST & Biblo LA: Prolonged QT interval and torsades de pointes caused by the combination of fluconazole and amitriptyline (letter). Am J Emerg Med 2000; 18:227-229. PubMed
Keep reading about Amitriptyline
Keep reading about Fluconazole
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