medicationPrescription only (US)Fluoxetine is an approved medicine; the cited literature reports trial outcomes, not dosing advice.
FluoxetineBenefits, Dosage & Interactions
Also known as: Prozac
Fluoxetine is a medication belonging to a class of drugs called selective serotonin reuptake inhibitors, or SSRIs. It is primarily used to treat major depressive disorder, obsessive-compulsive disorder (OCD), panic disorder, bulimia nervosa, and premenstrual dysphoric disorder (PMDD). It is typically taken in the morning.
How much Fluoxetine do people take?
Not stated here. The cited trials each used their own protocol amounts, and Fluoxetine is dosed by a prescriber or the approved product label — DoseRoutine records what you were told to take, it does not suggest an amount. Route reported: Oral (the route studied in the cited trials). Frequency reported: Set by the prescription or approved label, not by this record. These are amounts documented in the cited studies and labels for Fluoxetine — they are reported for reference, not a recommendation. Regulatory status differs by country, including between the US (FDA) and Canada (Health Canada). Confirm any amount with a licensed clinician before you take it.
See the full reported protocol and its sourcesResearched by DoseRoutine Research TeamReviewed for accuracy by Nicholas Alexander, RSE, SO, PMPLast updated Educational reference only — not medical advice. Always confirm dosing and safety decisions with a licensed clinician.
Evidence: Strong — 1266 human randomized trials and regulatory approval on file.
Evidence strengthStrong · 4/4
PreclinicalStrong human evidence
1266 human randomized trials and regulatory approval on file.
Plasma half-life
4–6 days
Typical timing
in the morning
Default unit
mg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
Reported for Fluoxetine in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the Fluoxetine entry is written from. Each number matches an inline marker above.
- [1]A randomized placebo-controlled trial of fluoxetine in body dysmorphic disorderPhillips KA, Albertini RS, Rasmussen SA · Arch Gen Psychiatry · 2002 · Peer-reviewed · PMID 11926939
- [2]Fluoxetine and congenital malformations: a systematic review and meta-analysis of cohort studiesGao SY, Wu QJ, Zhang TN, et al. · Br J Clin Pharmacol · 2017 · Peer-reviewed · PMID 28513059
References & Evidence
Sources on this page that document Fluoxetine dosing, timing and safety.
- [1]U.S. National Library of Medicine View source
- [2]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is Fluoxetine?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
Fluoxetine is a medication belonging to a class of drugs called selective serotonin reuptake inhibitors, or SSRIs. It is primarily used to treat major depressive disorder, obsessive-compulsive disorder (OCD), panic disorder, bulimia nervosa, and premenstrual dysphoric disorder (PMDD). It is also sometimes used in combination with olanzapine to treat bipolar depression and treatment-resistant depression. Fluoxetine works by increasing the levels of serotonin in the brain, a neurotransmitter associated with mood regulation. First approved by the FDA in 1987 under the brand name Prozac, it was one of the first SSRIs to be widely adopted and remains a commonly prescribed antidepressant. (NIH ODS, FDA label)
What does the research say about Fluoxetine?
Tap a section to expand.
Fluoxetine exerts its therapeutic effects primarily by selectively inhibiting the reuptake of serotonin by neurons in the central nervous system. Serotonin is a neurotransmitter that plays a crucial role in regulating mood, emotions, sleep, and appetite. When serotonin is released into the synaptic cleft (the space between neurons), it binds to receptors on the postsynaptic neuron to transmit a signal. After transmission, serotonin is normally reabsorbed by the presynaptic neuron through a process called reuptake. Fluoxetine blocks this reuptake pump, leading to an increased concentration of serotonin in the synaptic cleft. This prolonged presence of serotonin in the synapse allows it to continue stimulating postsynaptic receptors, which is thought to lead to improved mood and reduced symptoms of depression and anxiety over time. Unlike some older antidepressants, fluoxetine has very little effect on the reuptake of norepinephrine or dopamine, and it has low affinity for muscarinic, histaminergic, and alpha-adrenergic receptors, contributing to its more favorable side effect profile compared to tricyclic antidepressants. (PubChem, DrugBank)
Source for this section: Sources for How does Fluoxetine work?: Jumps to this entry in the sources and references list at the end of the page.
Fluoxetine is an effective treatment for several mental health conditions:
* **Major Depressive Disorder (MDD):** It helps alleviate symptoms of depression such as persistent sadness, loss of interest, fatigue, and sleep disturbances.
* **Obsessive-Compulsive Disorder (OCD):** It reduces the frequency and intensity of obsessive thoughts and compulsive behaviors.
* **Bulimia Nervosa:** It is used to reduce binge-eating and purging behaviors in individuals with this eating disorder.
* **Panic Disorder:** It helps to decrease the frequency and severity of panic attacks.
* **Premenstrual Dysphoric Disorder (PMDD):** It reduces severe mood symptoms, irritability, and physical symptoms associated with PMDD.
* **Bipolar Depression (in combination with olanzapine):** When used with olanzapine, it can treat depressive episodes associated with bipolar I disorder.
* **Treatment-Resistant Depression (in combination with olanzapine):** For individuals who have not responded to other antidepressant treatments, the combination with olanzapine may be effective.
The full therapeutic benefits of fluoxetine may take several weeks to become apparent. (FDA label, Mayo Clinic)
Numerous clinical trials and systematic reviews support the efficacy of fluoxetine for its approved indications. For example, a Cochrane review on antidepressants for major depression in adults found fluoxetine to be more effective than placebo and comparable to other active antidepressants in treating symptoms. Studies have shown its effectiveness in reducing the core symptoms of OCD, including both obsessions and compulsions, often showing improvement after several weeks of consistent use. In the treatment of bulimia nervosa, fluoxetine has demonstrated significant reductions in binge-eating and purging episodes in randomized controlled trials. Its role in panic disorder and PMDD is also well-established through clinical research, showing a reduction in symptom severity and frequency. The combination therapy of fluoxetine and olanzapine for bipolar depression and treatment-resistant depression has been evaluated in specific clinical trials demonstrating superior efficacy compared to either drug alone for these conditions. (Cochrane, FDA label, MedlinePlus)
Common side effects of fluoxetine can include nausea, insomnia, headache, nervousness, anxiety, diarrhea, drowsiness, and dry mouth. Some individuals may experience decreased libido, ejaculation disorder, or anorgasmia. Gastrointestinal issues such as indigestion and appetite changes leading to weight loss or gain can also occur. Less common but more serious side effects include serotonin syndrome (especially when combined with other serotonergic drugs), suicidal thoughts or behavior (particularly in young adults and adolescents), and prolonged QT interval. Ocular side effects such as mydriasis have also been reported. It's important to report any new or worsening symptoms to a healthcare provider. This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Source for this section: Sources for What are the side effects of Fluoxetine?: Jumps to this entry in the sources and references list at the end of the page.
Fluoxetine carries several important warnings. A black box warning from the FDA indicates an increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults (up to age 24) when taking antidepressants like fluoxetine. Close monitoring for worsening depression, suicidality, or unusual changes in behavior is essential, especially during the initial stages of treatment or when the dose is changed. Serotonin syndrome, a potentially life-threatening condition, can occur, especially when fluoxetine is used with other serotonergic drugs. Symptoms include agitation, hallucinations, rapid heart rate, fever, sweating, muscle rigidity, and incoordination. Discontinuation syndrome can occur if fluoxetine is stopped abruptly, leading to symptoms like dizziness, sensory disturbances (e.g., paresthesia), sleep disturbances, agitation, and anxiety. Tapering the dose gradually under medical supervision is typically recommended. Close monitoring is advised for patients with a history of seizures, glaucoma, or heart conditions due to potential risks. This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Source for this section: Sources for Who should avoid Fluoxetine?: Jumps to this entry in the sources and references list at the end of the page.
Fluoxetine is contraindicated in individuals with a known hypersensitivity to fluoxetine or any of its inactive ingredients. It should not be used concurrently with monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing an MAOI, as this significantly increases the risk of serotonin syndrome, which can be fatal. Similarly, it should not be started within 5 weeks of stopping fluoxetine if an MAOI is to be initiated due to the long half-life of fluoxetine and its active metabolite. Concomitant use with thioridazine is also contraindicated due to the risk of QT prolongation and ventricular arrhythmias. Use in patients with uncompensated narrow-angle glaucoma is a relative contraindication due to the potential for mydriasis. Caution is also advised in patients with severe renal or hepatic impairment, as dosage adjustments may be necessary. This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Source for this section: Sources for When should Fluoxetine not be taken?: Jumps to this entry in the sources and references list at the end of the page.
Fluoxetine should not be combined with:
* **Monoamine Oxidase Inhibitors (MAOIs):** Including phenelzine, selegiline, and tranylcypromine, due to a severe risk of serotonin syndrome. A washout period is required.
* **Thioridazine:** Due to a significant risk of QT prolongation and potentially fatal arrhythmias.
* **Pimozide:** Due to the risk of QT prolongation.
* **Other Serotonergic Drugs:** Including triptans (for migraines), tricyclic antidepressants, fentanyl, lithium, tramadol, tryptophan, buspirone, and St. John's Wort. Combining these can increase the risk of serotonin syndrome. If co-administration is necessary, careful monitoring is crucial.
* **Warfarin or other anticoagulants/antiplatelet drugs:** Fluoxetine can increase the risk of bleeding. Close monitoring is required.
* **Drugs metabolized by CYP2D6:** Fluoxetine is a potent inhibitor of CYP2D6, so it can increase the plasma concentrations of drugs like flecainide, propafenone, and metoprolol, leading to potential toxicity.
* **Alcohol:** Can exacerbate central nervous system depression and impair judgment.
This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Source for this section: Sources for What should you not mix with Fluoxetine?: Jumps to this entry in the sources and references list at the end of the page.
The typical timing for fluoxetine administration is once daily in the morning. This is often recommended to minimize the potential for insomnia, which can be a side effect. It can be taken with or without food. However, for some indications or in individuals experiencing specific side effects (e.g., nausea), a healthcare provider might suggest a different timing or taking it with food. The specific dose and timing must be user-directed and set by a licensed clinician based on the individual's condition and response. (FDA label)
Source for this section: Sources for When should you take Fluoxetine?: Jumps to this entry in the sources and references list at the end of the page.
Put it into practice
Reading about Fluoxetine is the first step — DoseRoutine helps you act on it. These free tools turn what you just learned into a routine.
What interacts with Fluoxetine?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Any supplement + medication | Note | Category ruleConfidence: theoretical | Some supplements change how the body processes medications (absorption, liver enzymes, or additive effects).Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Specific pairs are checked against a licensed drug database and shown with their own severity. Always confirm with your provider or pharmacist. |
| Any vitamin + medication | Note | Category ruleConfidence: theoretical | Certain vitamins interact with specific medications (e.g., vitamin K with blood thinners).Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Specific pairs are checked against a licensed source; confirm with your provider. |
| Phenelzine | Avoid | Compound pairConfidence: theoretical | Combining SSRIs/SNRIs with MAOIs can cause life-threatening serotonin syndrome.Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Do not combine. Allow at least 14 days between stopping one and starting the other (5 weeks for fluoxetine). |
| Tranylcypromine | Avoid | Compound pairConfidence: theoretical | Combining SSRIs/SNRIs with MAOIs can cause life-threatening serotonin syndrome.Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Do not combine. Allow at least 14 days between stopping one and starting the other (5 weeks for fluoxetine). |
| Selegiline | Avoid | Compound pairConfidence: theoretical | Combining SSRIs/SNRIs with MAOIs can cause life-threatening serotonin syndrome.Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Do not combine. Allow at least 14 days between stopping one and starting the other (5 weeks for fluoxetine). |
| Rasagiline | Avoid | Compound pairConfidence: theoretical | Combining SSRIs/SNRIs with MAOIs can cause life-threatening serotonin syndrome.Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Do not combine. Allow at least 14 days between stopping one and starting the other (5 weeks for fluoxetine). |
| 5-HTP | Avoid | Compound pairConfidence: theoretical | 5-HTP raises serotonin and layered onto an SSRI/SNRI risks serotonin syndrome.Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Avoid combining 5-HTP with prescription serotonergic antidepressants. |
| L-Tryptophan | Caution | Compound pairConfidence: theoretical | Additional serotonin precursor with an SSRI/SNRI can push serotonin too high.Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Do not combine without a prescribing clinician's guidance. |
| St John's Wort | Avoid | Compound pairConfidence: theoretical | St John's Wort has serotonergic activity and induces CYP3A4, altering SSRI levels.Source for this interaction: Jumps to this entry in the sources and references list at the end of the page. | Avoid combining. |
Frequently asked questions about Fluoxetine
While some individuals may notice minor improvements within a week or two, the full therapeutic effects of fluoxetine, especially for mood and anxiety disorders, typically take 4 to 6 weeks to become apparent. It's important to continue taking the medication as prescribed even if immediate changes aren't felt. (MedlinePlus)
Weight changes can occur with fluoxetine, though the effect varies among individuals. Some people may experience weight loss, especially early in treatment due to appetite changes or nausea, while others might experience weight gain with long-term use. If you are concerned about weight changes, discuss this with your healthcare provider. (FDA label)
Fluoxetine is not considered addictive in the same way as opioids or stimulants. However, abruptly stopping fluoxetine, particularly after long-term use, can lead to withdrawal-like symptoms, often called antidepressant discontinuation syndrome. These symptoms can include dizziness, nausea, headache, anxiety, and sleep disturbances, which is why a gradual reduction in dose under medical supervision is usually recommended. (NIH ODS)
Fluoxetine is generally recommended to avoid or limit alcohol consumption while taking fluoxetine. Alcohol can intensify some of the side effects of fluoxetine, such as drowsiness, dizziness, and impaired judgment. While not a strict contraindication, combining the two can worsen symptoms of depression or anxiety and impair your ability to drive or perform other tasks requiring alertness. (FDA label)
Fluoxetine has a relatively long half-life, averaging about 4 to 6 days (96 to 144 hours). Its major active metabolite, norfluoxetine, also has a long half-life of 4 to 16 days. This long half-life is why a washout period is required before starting other medications, particularly MAOIs, and why withdrawal symptoms may be less immediate or intense compared to SSRIs with shorter half-lives. (DrugBank)
Interaction risk for Fluoxetine comes from the rest of the stack: other medications, prescription medicines, hormone therapy and peptides. Because Fluoxetine is usually taken in the morning, most avoidable conflicts come from what else lands in that same window. With a reported plasma half-life near 96 hours, separating doses can change the picture as much as removing one. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers Fluoxetine with no sign-up.
Fluoxetine is typically taken in the morning. The reported plasma half-life is about 96 hours, which is what drives how often it is redosed. Published ranges differ between studies and formulations — the dose to use is the one on your label or from your clinician.
There is no single answer for Fluoxetine plus TRT. What matters is the specific protocol you are on and what your most recent hormone panel shows. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
Pairing Fluoxetine with peptides has to be assessed one peptide at a time, because GLP-1 agonists, secretagogues, healing peptides and melanocortins do not share an interaction profile. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
A long plasma half-life of about 96 hours means Fluoxetine is commonly dosed every few days or weekly rather than daily. It is typically taken in the morning. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
With a plasma half-life near 96 hours, a single missed dose of Fluoxetine usually has a smaller effect on overall exposure than an irregular pattern of missed doses does. Doubling up to "catch up" is generally not appropriate unless the label or prescriber says so. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For Fluoxetine the useful record is the dose, the time it was actually taken, and what else was taken in the same window. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
Not stated here. The cited trials each used their own protocol amounts, and Fluoxetine is dosed by a prescriber or the approved product label — DoseRoutine records what you were told to take, it does not suggest an amount. Route reported: Oral (the route studied in the cited trials). Frequency reported: Set by the prescription or approved label, not by this record. These are amounts documented in the cited studies and labels for Fluoxetine — they are reported for reference, not a recommendation. Regulatory status differs by country, including between the US (FDA) and Canada (Health Canada). Confirm any amount with a licensed clinician before you take it.
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- MedlinePlus(opens in a new tab)U.S. National Library of Medicine · medlineplus.gov/druginfo/meds/a689006.html
- PubChem CID 57369875(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/57369875
Verify at
Publisher search links for Fluoxetine. These are places to check the information — they are not citations, so they are not numbered.
- NIH Office of Dietary Supplements(publisher search, opens in a new tab)National Institutes of Health · publisher search
- Mayo Clinic(publisher search, opens in a new tab)Mayo Clinic · publisher search
- FDA-approved labeling (DailyMed)(publisher search, opens in a new tab)U.S. Food and Drug Administration · publisher search
- European Medicines Agency(publisher search, opens in a new tab)European Medicines Agency · publisher search
- Cochrane Library(publisher search, opens in a new tab)Cochrane · publisher search
- DrugBank(publisher search, opens in a new tab)DrugBank Online · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on Fluoxetine?
Plain-text summary, safe to quote verbatim:
Fluoxetine is a medication belonging to a class of drugs called selective serotonin reuptake inhibitors, or SSRIs. It is primarily used to treat major depressive disorder, obsessive-compulsive disorder (OCD), panic disorder, bulimia nervosa, and premenstrual dysphoric disorder (PMDD). It is typically taken in the morning.
Source: DoseRoutine — https://doseroutine.com/library/fluoxetine
Fluoxetine cheat sheet
DoseRoutine cheat sheet · Medication
Fluoxetine
Fluoxetine is a medication belonging to a class of drugs called selective serotonin reuptake inhibitors, or SSRIs. It is primarily used to treat major depressive disorder, obsessive-compulsive disorder (OCD), panic disorder, bulimia nervosa, and premenstrual dysphoric disorder (PMDD).
Evidence
Strong
1266 human randomized trials and regulatory approval on file.
Studied range
Not stated here. The cited trials each used their own protocol amounts, and Fluoxetine is dosed by a prescriber or the approved product label — DoseRoutine records what you were told to take, it does not suggest an amount.
Route
Oral (the route studied in the cited trials)
Frequency studied
Set by the prescription or approved label, not by this record
Half-life
4–6 days
Timing
in the morning
Storage
Room temperature, in the original container, away from moisture
Prescription only (US)Fluoxetine is an approved medicine; the cited literature reports trial outcomes, not dosing advice.
Studied ranges, not dosing advice. Not medical advice — talk to a clinician. doseroutine.com/library/fluoxetine
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). Fluoxetine — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/fluoxetine
What compounds are similar to Fluoxetine?
Others in the medication category or studied for the same goals.