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Prozac (Fluoxetine) Tapering Calculator

Prozac is, generally, the easiest common antidepressant to come off — its long half-life (≈ 4-6 days; longer for the active metabolite) means blood levels self-taper between doses. The calculator below pre-fills for fluoxetine.

Fluoxetine (Prozac) is the longest-half-life SSRI. Because its active metabolite norfluoxetine persists for 7–15 days, dose reductions take much longer to "show up" in symptoms. This is why fluoxetine is occasionally used as a "bridge" when stopping shorter half-life drugs like venlafaxine or paroxetine — a decision your prescriber should make and supervise.

The calculator below pre-fills the moderate preset for fluoxetine. Even with the long half-life, the final milligrams should still be reduced hyperbolically using the liquid.

Example schedule for fluoxetine

This preview uses a typical starting dose and the default taper speed for fluoxetine. The first steps of the hyperbolic schedule are shown below — enter your email to receive the full protocol and unlock the chart.

Starting dose
20 mg/day · 1× daily
Taper speed
Moderate
Region (formulations)
US
Modelled occupancy at start
~70.8%
Withdrawal risk: lower (population average)

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Schedule preview

First steps shown below. Enter your email to receive the complete fluoxetine protocol and unlock the occupancy chart.

StepDaily (mg)How to take itHold (wk)
020Your current dose — hold steady before step 1.
116.4Measure 4.1 mL of 4 mg/mL oral solution (≈ 16.4 mg active ingredient). Use an oral syringe; confirm concentration on the bottle.2
213.75Measure 3.438 mL of 4 mg/mL oral solution (≈ 13.75 mg active ingredient). Use an oral syringe; confirm concentration on the bottle.2
StepDaily (mg)How to take itHold (wk)
310Take 1 × 10 mg Prozac tablet (10 mg active ingredient total).2
48.7Take half of a scored 20 mg tablet (10 mg) ≈ 8.7 mg active ingredient.2
57.6Take half of a scored 20 mg tablet (10 mg) ≈ 7.6 mg active ingredient.2
66.7Take half of a scored 20 mg tablet (10 mg) ≈ 6.7 mg active ingredient.2

⚠️ It's not a substitute for medical advice. This calculator can help you visualise a tapering schedule but before making any changes to your medication plan it's necessary to consult a medical professional. Ask a psychiatrist — available after you request your protocol.

Dose vs occupancy

This taper is spread across 17 gradual steps.

What this shows: the non-linear relationship between dose and serotonin transporter (SERT) occupancy. The curve is flat at high doses — most transporters are already blocked, so a dose cut has little biological impact — and much steeper at low doses, where even a 1–2 mg reduction causes a disproportionately large drop in occupancy. Your taper steps are spaced along this curve so each step removes a similar amount of occupancy.

Hill curve of modelled receptor occupancy versus dose. Current dose near 20.0 milligrams per day.

Modelled Hill-curve occupancy — illustrative only. PET-derived parameters vary by study; your prescriber may use different clinical targets. Small mg changes near zero can still produce large occupancy shifts.

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Use the guided builder to enter your current dose, region, and taper preset — then email your personalised protocol.

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This schedule is a map, not a rule. Wait until symptoms from the previous step have settled before reducing again — and review every change with your prescriber.

Key facts about hyperbolic antidepressant tapering

The calculator algorithm is based on peer-reviewed research and has been reviewed by our medical advisors to ensure the accuracy of the tapering model.

  • 72%

    discontinued their antidepressant using hyperbolic tapering strips in a real-world study

    71% of the same people had previously tried to stop at least once and been unsuccessful; the study did not record which method those earlier attempts used. Figures come from tapering-strip research and may not generalise to every taper.

    Source: Groot et al., Therapeutic Advances in Psychopharmacology 2021

  • 56 days

    median taper length in that tapering-strip study — not a target; many people taper over 6–12 months or longer

    This median reflects tapering-strip use in one study. Your timeline depends on how long you have taken the medication, your withdrawal symptoms, and previous attempts — slower is often safer.

    Source: Groot et al., Therapeutic Advances in Psychopharmacology 2021

  • 10%

    serotonin transporter occupancy per tapering step

    This linear reduction prevents withdrawal. Slower, more gradual tapering over several months has shown greater success in reducing withdrawal symptoms than short tapers.

    Source: Horowitz et al., The Lancet Psychiatry 2019

Frequently asked questions about fluoxetine

Common questions about tapering off fluoxetine, reviewed by our clinical advisors.

  • Is it easier to taper Prozac (fluoxetine) than other antidepressants?

    Yes — generally. Fluoxetine has a very long half-life (≈ 4-6 days; longer for its active metabolite norfluoxetine), so blood levels drop slowly when you reduce or stop. Many people taper successfully with relatively large steps. Even so, the final milligrams should still be reduced hyperbolically using the liquid formulation.

  • What is an antidepressant tapering calculator?

    An antidepressant tapering calculator is a free online medication taper calculator that turns your current dose into a step-by-step plan for reducing it over time. The Claro calculator uses the hyperbolic method: each step removes a similar percentage of receptor occupancy rather than the same number of milligrams. The result is a personalised schedule you can review with your prescriber when you decide to wean off antidepressants.

  • Why use a tapering calculator?

    A tapering calculator turns the pharmacology research on receptor occupancy into a concrete schedule you can read in minutes. It is especially useful when you want to come off antidepressants gradually, because the last few milligrams cause the largest change in modelled occupancy. The calculator helps you see the steps in advance, plan the right liquid or split-tablet doses, and bring a printable schedule to your prescriber.

  • How does an antidepressant taper calculator work?

    The calculator models how much of your serotonin (or noradrenaline) transporter is occupied at each dose using a Hill-equation curve fitted to published PET studies. It then chooses dose reductions so that each step removes a roughly equal amount of occupancy — the hyperbolic method described by Horowitz and Taylor (2019). The schedule is then rounded to doses you can actually achieve with available tablets, capsules, or liquids in your region.

  • What is hyperbolic tapering and why is it recommended?

    Hyperbolic tapering means reducing your dose by smaller and smaller milligram amounts as you get lower, so the change in receptor occupancy at each step stays about the same. It is recommended because antidepressants follow a hyperbolic dose-response curve: at low doses, small milligram changes have outsized effects. Hyperbolic tapering is endorsed in the Maudsley Deprescribing Guidelines (2024), the UK NICE NG222 guideline, and the Dutch multidisciplinary deprescribing document.

  • What is the safest way to taper off antidepressants?

    The safest way is gradual, supervised, and individualised. Work with a prescriber, hold each dose for at least 2-4 weeks before reducing again, and use liquid or compounded formulations once tablets cannot be split small enough. If symptoms become severe, return to the previous stable dose, allow time to settle, then resume with smaller steps. This calculator is educational; do not change medication without clinical supervision.

  • How slowly should antidepressants be reduced?

    Most people benefit from reductions of around 5-10% of the previous dose every 2-4 weeks, and even more slowly toward the end of the taper. Higher-risk drugs — paroxetine, venlafaxine, and duloxetine — typically need slower steps and longer holds. There is no fixed timeline: many people take 6-12 months to fully get off antidepressants and some take longer, especially after years of treatment.

  • What are common antidepressant withdrawal symptoms?

    The most commonly reported antidepressant withdrawal symptoms include dizziness, "brain zaps" (brief electric-shock sensations), nausea, fatigue, insomnia, vivid dreams, headaches, irritability, anxiety, and mood swings. A 2024 Lancet Psychiatry meta-analysis (Henssler et al.) estimated discontinuation symptoms in around 31% of people, with about 2.8% experiencing severe symptoms. Earlier work (Davies & Read, 2019) reported higher rates of 56% across surveyed populations.

  • What is the difference between antidepressant withdrawal and relapse?

    Withdrawal usually starts within days of a dose reduction, includes physical symptoms like dizziness or brain zaps, and improves when you reinstate the previous dose. Relapse of the original condition typically appears weeks later, is dominated by your original symptoms, and is not relieved within hours by reinstating. The Cosci & Chouinard (2020) framework is the standard taxonomy clinicians use to tell the two apart.

  • Is it dangerous to stop antidepressants cold turkey?

    Stopping antidepressants cold turkey is widely discouraged. Sudden discontinuation increases the risk of severe withdrawal symptoms, including dizziness, brain zaps, and emotional changes, and can trigger reinstatement. Short half-life drugs such as paroxetine and venlafaxine carry the highest risk. If you have already stopped abruptly and feel unwell, contact your prescriber; reinstating the previous dose and then tapering more gradually is the standard recommendation.

  • Why are the last antidepressant dose reductions often the hardest?

    Because the dose-occupancy curve is hyperbolic. At low doses, a 1-2 mg change can produce as much receptor change as a 10-20 mg change at higher doses. This is why people often feel fine for most of the taper and then struggle at the end. A medication taper calculator addresses this by making the final steps in tenths of a milligram, which usually requires a liquid formulation or compounded preparation.

  • Which antidepressants are hardest to taper off?

    Paroxetine (Paxil/Seroxat) and venlafaxine (Effexor) are most often reported as the hardest antidepressants to come off, followed by duloxetine (Cymbalta). They share short half-lives and steep dose-occupancy curves, so missed doses or sharp reductions can trigger withdrawal symptoms within days. Fluoxetine (Prozac), with its very long half-life, is generally the easiest and is sometimes used as a "bridge" when switching off shorter-acting drugs.

Clinical references

  1. [1]Horowitz MA, Taylor D. Tapering of SSRI treatment to mitigate withdrawal symptoms. The Lancet Psychiatry 2019. doi:10.1016/S2215-0366(19)30032-XProposes hyperbolic dose reduction based on receptor-occupancy curves; the methodological basis of every modern taper calculator.
  2. [2]Horowitz MA, Taylor D. The Maudsley Deprescribing Guidelines. Wiley 2024. doi:10.1002/9781394291052Per-drug operational manual for hyperbolic tapering across SSRIs, SNRIs, benzodiazepines, gabapentinoids, and antipsychotics.
  3. [3]Davies J, Read J. A systematic review into the incidence, severity and duration of antidepressant withdrawal effects. Addictive Behaviors 2019. doi:10.1016/j.addbeh.2018.08.027Systematic review: 56% of people who discontinue antidepressants experience withdrawal effects; 46% rate them as severe.
  4. [4]Henssler J et al. Incidence of antidepressant discontinuation symptoms: a systematic review and meta-analysis. The Lancet Psychiatry 2024. doi:10.1016/S2215-0366(24)00133-0Meta-analysis of 79 studies (≈21,000 patients): pooled incidence of discontinuation symptoms ~31%; severe symptoms ~2.8%.
  5. [5]Groot PC, van Os J. Successful use of tapering strips for hyperbolic reduction of antidepressant dose: a cohort study. Therapeutic Advances in Psychopharmacology 2021. doi:10.1177/2045125321103932772% of patients successfully discontinued antidepressants after switching to the hyperbolic model; 71% had previously failed to come off without tapering strips.
  6. [6]Groot PC, van Os J. Antidepressant tapering strips to help people come off medication: real-world outcomes. Therapeutic Advances in Psychopharmacology 2023. doi:10.1177/20451253231171518Of 1,194 patients using hyperbolic taper strips after previous failed attempts, ~71% successfully discontinued their antidepressant.
  7. [7]Framer A. What I have learnt from helping thousands of people taper off antidepressants and other psychotropic medications. Therapeutic Advances in Psychopharmacology 2021. doi:10.1177/2045125321991274Describes the "windows and waves" pattern of withdrawal recovery and supports patient-led pacing.
  8. [8]Hengartner MP et al. Protracted withdrawal syndrome after stopping antidepressants: a descriptive quantitative analysis of consumer narratives. Therapeutic Advances in Psychopharmacology 2020. doi:10.1177/2045125320967183Descriptive analysis of 69 protracted withdrawal cases: median duration 79 weeks; 47% report suicidality during withdrawal.
  9. [9]Cosci F, Chouinard G. Acute and persistent withdrawal syndromes following discontinuation of psychotropic medications. Psychotherapy and Psychosomatics 2020. doi:10.1159/000506868Taxonomy distinguishing new withdrawal symptoms, rebound, and persistent post-withdrawal disorder; the standard framework for withdrawal vs. relapse.
  10. [10]Kalfas M et al. Incidence and Nature of Antidepressant Discontinuation Symptoms. JAMA Psychiatry 2025. doi:10.1001/jamapsychiatry.2025.1362Recent meta-analysis: dizziness was the most common discontinuation symptom in the first 2 weeks after stopping antidepressants, followed by nausea, vertigo, and nervousness.
  11. [11]Gabriel M, Sharma V. Antidepressant discontinuation syndrome. Canadian Medical Association Journal 2017. doi:10.1503/cmaj.160991Clinical review of antidepressant discontinuation syndrome: onset within days of dose reduction, typical symptom course, and management.
  12. [12]Papp A, Onton J. Brain Zaps: An Underappreciated Symptom of Antidepressant Discontinuation. The Primary Care Companion for CNS Disorders 2018. doi:10.4088/pcc.18m02311Characterises "brain zaps" — brief electric-shock sensations — as a common antidepressant discontinuation symptom.
  13. [13]Wang J, Cosci F. Acute and persistent withdrawal syndromes following discontinuation of antidepressants in children and adolescents: a systematic review. Therapeutic Advances in Psychopharmacology 2025. doi:10.1177/20451253251404780Systematic review of acute and persistent antidepressant withdrawal syndromes; reinforces reducing only when stable and under supervision.
  14. [14]Horowitz M, Taylor D. Distinguishing relapse from antidepressant withdrawal: clinical practice and antidepressant discontinuation studies. BJPsych Advances 2022. doi:10.1192/bja.2021.62Frames how clinicians can distinguish antidepressant withdrawal from relapse of the underlying condition.
  15. [15]Sørensen A, Ruhé HG, Munkholm K. The relationship between dose and serotonin transporter occupancy of antidepressants — a systematic review. Molecular Psychiatry 2021. doi:10.1038/s41380-021-01285-wSystematic review of dose–SERT-occupancy relationships across antidepressants; confirms the hyperbolic curve underlying proportional tapering.
  16. [16]Reeve R, Turner JR. Pharmacodynamic models: parameterizing the Hill equation, Michaelis-Menten, the logistic curve, and relationships among these models. Journal of Biopharmaceutical Statistics 2013. doi:10.1080/10543406.2012.756496Explains how the Hill equation, Michaelis-Menten, and logistic models relate — the mathematical basis for the occupancy curve used here.
  17. [17]Preskorn SH. The use of biomarkers in psychiatric research: how serotonin transporter occupancy explains the dose-response curves of SSRIs. Journal of Psychiatric Practice 2012. LinkShows how SERT occupancy explains the non-linear dose–response curves of SSRIs.
  18. [18]Cohrs D, Shapiro B. The relationship between SERT occupancy and extracellular serotonin concentration is hyperbolic, not linear: implications for safely tapering SRI antidepressants. SSRN (preprint) 2026. doi:10.2139/ssrn.6176553Argues the SERT-occupancy to serotonin relationship is itself hyperbolic, reinforcing proportional (hyperbolic) tapering.
  19. [19]Moncrieff J et al. Evidence on antidepressant withdrawal: an appraisal and reanalysis of a recent systematic review. Psychological Medicine 2025. doi:10.1017/S0033291725100652Reappraisal of recent withdrawal-incidence evidence; relevant to how withdrawal rates are interpreted.
  20. [20]Wilson E, Lader M. A review of the management of antidepressant discontinuation symptoms. Therapeutic Advances in Psychopharmacology 2015. doi:10.1177/2045125315612334Practical review of how to manage antidepressant discontinuation symptoms, including tapering and reinstatement.
  21. [21]Groot PC, van Os J. Outcome of antidepressant drug discontinuation with tapering strips after 1–5 years. Therapeutic Advances in Psychopharmacology 2020. doi:10.1177/2045125320954609Long-term follow-up (1–5 years) of patients who discontinued antidepressants using hyperbolic taper strips.
  22. [22]Gury C, Cousin F. Pharmacokinetics of SSRI antidepressants: half-life and clinical applicability. L'Encéphale 1999. LinkHalf-life data for SSRIs — explains why short-half-life drugs (paroxetine, venlafaxine) provoke faster withdrawal.
  23. [23]Mayo Clinic. Antidepressant withdrawal: Is there such a thing?. Mayo Clinic — Expert Answers 2024. LinkPatient-facing explainer on antidepressant discontinuation symptoms and gradual tapering.
  24. [24]NHS Scotland — Right Decision Service. Antidepressants — quality prescribing: difficulty withdrawing from an SSRI/SNRI. NHS Scotland 2024. LinkNHS Scotland guidance on recognising and managing difficulty withdrawing from SSRIs/SNRIs.
  25. [25]The Carlat Psychiatry Report. Clinical pearls for hyperbolic tapering of psychiatric medications in older adults. The Carlat Report 2024. LinkPractical clinical pearls for applying hyperbolic tapering, including in older adults.
  26. [26]Royal College of Psychiatrists. Stopping antidepressants — information for patients and carers. Royal College of Psychiatrists 2024. LinkRCPsych patient-facing guidance on coming off antidepressants safely.
  27. [27]Meyer JH et al. Serotonin transporter occupancy of five selective serotonin reuptake inhibitors at different doses. American Journal of Psychiatry 2004. doi:10.1176/appi.ajp.161.5.826PET-imaged SERT occupancy data for citalopram, sertraline, paroxetine, fluoxetine, and venlafaxine — the empirical basis for the hyperbolic curves in this calculator.
  28. [28]National Institute for Health and Care Excellence (NICE). Depression in adults: treatment and management. NICE guideline [NG222]. NICE 2022. LinkUK national guideline endorsing proportional (hyperbolic) tapering and the use of liquid formulations to enable small final doses.
  29. [29]Royal College of Psychiatrists. Stopping antidepressants — position statement (CR225). Royal College of Psychiatrists 2020. LinkRCPsych acknowledges withdrawal can be severe and long-lasting; recommends slow, individualised tapers.
  30. [30]NHG et al. Multidisciplinary document: Discontinuation of SSRIs and SNRIs (2018; revised 2023). Multidisciplinary Document (Netherlands) 2018. LinkFirst national guideline to explicitly endorse hyperbolic tapering and the use of taper strips (compounded by Regenboog Apotheek).
  31. [31]Medicines and Healthcare products Regulatory Agency (MHRA). Summary of Product Characteristics — SSRI and SNRI products (UK). electronic Medicines Compendium (emc) 2023. LinkAuthoritative UK formulary data (tablet strengths, oral solutions) used to validate the UK region in the calculator.
  32. [32]U.S. Food and Drug Administration. Prescribing information (Structured Product Labeling) for SSRI/SNRI products. FDA / DailyMed 2024. LinkAuthoritative US formulary data (tablet strengths, oral solutions/concentrates) used to validate the US region in the calculator.
  33. [33]Health Canada. Health Canada — Drug Product Database. Health Canada 2024. LinkAuthoritative Canadian formulary data used to validate the Canada region in the calculator.
  34. [34]Therapeutic Goods Administration (TGA). Therapeutic Goods Administration — Australian Register of Therapeutic Goods (ARTG). TGA / ARTG 2024. LinkAuthoritative Australian formulary data used to validate the Australia region in the calculator.
  35. [35]College ter Beoordeling van Geneesmiddelen (CBG-MEB). CBG-MEB — Medicines Information Bank (Netherlands). CBG-MEB 2024. LinkAuthoritative Dutch formulary data; cross-checked with Regenboog Apotheek taper-strip availability.
  36. [36]Regenboog Apotheek, Cinetto. Taperingstrip.com — Regenboog Apotheek. Patient resource (NL) 2024. LinkPioneer of standardised taper strips referenced in the Dutch national guideline.

Claro — tapering companion

A protocol isn’t enough — you need support.

Tapering can take months, sometimes years. Claro helps you track each step, log symptoms, and spot when a reduction was too fast — with psychiatrist-reviewed guidance. Join early access while we launch the app.

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