Fluoxetine: Difference between revisions
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| mechanism = TrkB/BDNF<ref name="trkb">S1</ref> <vote slug="ssri-claim">Fluoxetine is a selective serotonin reuptake inhibitor.</vote> | | mechanism = TrkB/BDNF<ref name="trkb">S1</ref> <vote slug="ssri-claim">Fluoxetine is a selective serotonin reuptake inhibitor.</vote> | ||
| intro = Fluoxetine was the first of a long line of SSRIs. It is notable for its extremely long half-life and relative lack of withdrawal syndrome. It can also be useful in helping taper and discontinue other SxRI meds. | | intro = Fluoxetine was the first of a long line of SSRIs. It is notable for its extremely long half-life and relative lack of withdrawal syndrome. It can also be useful in helping taper and discontinue other SxRI meds. | ||
| indications = < | | indications = <problem ref="depression" author="MDElliottMD"/> | ||
< | <problem ref="anxiety-disorders" author="MDElliottMD"> | ||
Including generalized anxiety, panic, and social anxiety. | Including generalized anxiety, panic, and social anxiety. | ||
</ | </problem> | ||
< | <problem ref="panic" author="MDElliottMD"/> | ||
< | <problem ref="social-anxiety" author="MDElliottMD"/> | ||
< | <problem ref="ocd" author="MDElliottMD"/> | ||
< | <problem ref="ptsd" author="MDElliottMD"> | ||
Potentially. | Potentially. | ||
</ | </problem> | ||
< | <problem ref="premature-ejaculation"/> | ||
| dosing = <titration slug="standard" author="MDElliottMD" title="Standard adult or child"> | | dosing = <titration slug="standard" author="MDElliottMD" title="Standard adult or child"> | ||
Start no higher than 10 mg for the first dose. May increase by 10 mg every 2–12 weeks, or remain at 10 mg if the response is adequate, up to a typical starting maximum of 40 mg. Absolute max: 80 mg. | Start no higher than 10 mg for the first dose. May increase by 10 mg every 2–12 weeks, or remain at 10 mg if the response is adequate, up to a typical starting maximum of 40 mg. Absolute max: 80 mg. | ||
Revision as of 00:11, 17 May 2026
SSRI, Anxiolytic, Antidepressant
Fluoxetine
Prozac
Fluoxetine was the first of a long line of SSRIs. It is notable for its extremely long half-life and relative lack of withdrawal syndrome. It can also be useful in helping taper and discontinue other SxRI meds.
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None required
Sertraline, Duloxetine
Experience
No personal reports yet
1 provider report · avg efficacy 40.0/100 · avg side-effect burden 40.0/100 · 150 patients managed total
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Problems
Depressive disorders1.1n=1
Including generalized anxiety, panic, and social anxiety.
Panic disorder1.5n=2
Social anxiety disorder2.0n=1
PTSD1.0n=1
Potentially.
Premature ejaculation2.1n=2
Titration strategies
Standard adult or child+1
Start no higher than 10 mg for the first dose. May increase by 10 mg every 2–12 weeks, or remain at 10 mg if the response is adequate, up to a typical starting maximum of 40 mg. Absolute max: 80 mg.
OCD+1
Start at 10 mg daily; increase by 10–20 mg every 2–6 weeks, up to 80 mg. OCD typically requires elevated doses (60–80 mg).
Effects
- Anxiolysis no reports yet ~33% +67.0 (n=1)Classically starting at 3–4 weeks and improving for another 8–12.Did you experience this?How often have you seen this?How was it? (-100 worst, +100 best)How was it? (-100 worst, +100 best)
- Delayed orgasm/ejaculation 0% — (n=3) ~80% +33.0 (n=1)Did you experience this?How often have you seen this?How was it? (-100 worst, +100 best)How was it? (-100 worst, +100 best)
- Mood enhancement no reports yet ~5% +67.0 (n=1)Did you experience this?How often have you seen this?How was it? (-100 worst, +100 best)How was it? (-100 worst, +100 best)
- Nausea no reports yet ~5% -33.0 (n=1)Common, often improves over 1–2 weeks.Did you experience this?How often have you seen this?How was it? (-100 worst, +100 best)How was it? (-100 worst, +100 best)
- Decreased libido no reports yet ~33% -100.0 (n=1)Did you experience this?How often have you seen this?How was it? (-100 worst, +100 best)How was it? (-100 worst, +100 best)
- Temporary erectile dysfunction no reports yet ~20% -67.0 (n=1)Did you experience this?How often have you seen this?How was it? (-100 worst, +100 best)How was it? (-100 worst, +100 best)
- Persistent Sexual Dysfunction no reports yet ~0% -100.0 (n=1)Historically associated with SSRIs.Did you experience this?How often have you seen this?How was it? (-100 worst, +100 best)How was it? (-100 worst, +100 best)
Anorgasmia no reports yet ~5% -100.0 (n=1)
Did you experience this?
How often have you seen this?
How was it? (-100 worst, +100 best)How was it? (-100 worst, +100 best)
Pharmacokinetics
Absorption
70–90%[3] oral bioavailability.Distribution
Fluoxetine has plasma protein binding of approximately 94.5%, bound to albumin and alpha-1 glycoprotein. Fluoxetine readily crosses the blood–brain barrier, with a brain-to-plasma ratio of 2.6:1 in humans. The volume of distribution (Vd) of fluoxetine and its metabolite ranges between 20 to 42 L/kg. Some studies report that fluoxetine has the maximum volume of distribution (Vd) of any SSRI (between 14 and 100 L/kg).[3]Metabolism
Fluoxetine's active metabolite is norfluoxetine, produced when the cytochrome P450 enzyme (CYP2D6) acts on it. Prescribers must remember that fluoxetine has several med-med interactions due to its metabolism through the CYP2D6 isoenzyme. Additionally, norfluoxetine can have an inhibitory effect on CYP3A4. Fluoxetine has a half-life of 2 to 4 days, and its active metabolite norfluoxetine has a half-life of 7 to 9 days. Approximately 7% of individuals definitively exhibit poor metabolism of fluoxetine due to reduced activity of CYP2D6.[3]Monitoring
Relevant anecdote
⚕️ Provider 0
Fluoxetine is great for getting off other SxRIs! Especially venlafaxine and duloxetine.
Relevant Literature
No literature entries yet.
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See also
References
Summary
Classes
SSRI, Anxiolytic, Antidepressant
Common uses
- Premature ejaculation2.1n=2
- Anxiety disorders broadly1.5n=2
- Panic disorder1.5n=2
- Depressive disorders1.1n=1
- Embarrassment0.5n=3
Pharmacy
Starting dose
10 mg
Preparations
10 mg, 20 mg, 40 mg caps
US FDA Max
40 mg/d
Pill ID
- 10 mg: green/cream capsule, "PLIVA 647"
- 20 mg: green/cream capsule, "PROZAC 20"
- 40 mg: olive/cream capsule, "DISTA 3107"
- Oral solution: 20 mg / 5 mL, clear