Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PAXIL vs LUVOX
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Paroxetine is a selective serotonin reuptake inhibitor (SSRI) that potentiates serotonergic activity in the central nervous system by inhibiting the reuptake of serotonin (5-HT) from the synaptic cleft, leading to increased serotonin levels.
Selective serotonin reuptake inhibitor (SSRI); increases serotonergic activity by blocking reuptake of serotonin into presynaptic neurons.
Major depressive disorder,Obsessive-compulsive disorder,Panic disorder,Social anxiety disorder,Generalized anxiety disorder,Post-traumatic stress disorder,Premenstrual dysphoric disorder (off-label),Vasomotor symptoms of menopause (off-label)
Obsessive-compulsive disorder (OCD),Social anxiety disorder,Panic disorder,Premenstrual dysphoric disorder (PMDD),Bulimia nervosa,Post-traumatic stress disorder (PTSD)
20 mg orally once daily, typically in the morning; may be increased in 10 mg/day increments at intervals of at least 1 week to a maximum of 50 mg/day.
Initial dose 50 mg orally once daily at bedtime, titrated by 50 mg increments every 4-7 days to effective dose; usual therapeutic range 100-300 mg/day divided once daily (at bedtime) or twice daily if tolerated. Maximum dose 300 mg/day.
Mean terminal half-life 21 hours (range 3–65 hours); steady-state achieved within 7–14 days; nonlinear kinetics with dose increase leading to disproportionate increases in half-life due to saturable hepatic metabolism (CYP2D6).
The terminal elimination half-life is approximately 15-20 hours but may be prolonged in patients with hepatic impairment or with advanced age. Steady-state is typically achieved within 7-10 days of chronic dosing.
Extensively metabolized primarily via cytochrome P450 (CYP) 2D6, with minor contributions from CYP3A4 and CYP1A2. The parent drug accounts for <1% of excretion. Metabolites include paroxetine catechol and paroxetine glucuronide conjugates.
Primarily hepatic via CYP1A2; minor pathways via CYP2D6; active metabolites minimal.
Renal: 64% (2% unchanged, 62% as metabolites); Fecal: 36% via bile; urinary excretion of unchanged paroxetine <2%.
Approximately 94% of a dose is excreted in urine, mostly as conjugated and oxidized metabolites, with 2% as unchanged drug. Fecal excretion accounts for less than 4%.
93–95% bound to plasma proteins (primarily alpha-1-acid glycoprotein and albumin).
Approximately 80% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
11 L/kg (range 3–28 L/kg); extensive tissue distribution with concentrations in CNS exceeding plasma.
The apparent volume of distribution is about 4.7 L/kg, indicating extensive extravascular distribution and tissue binding, which contributes to its long half-life.
Oral: 50% (range 30–60%; limited by first-pass metabolism); food does not significantly affect extent of absorption, but may slightly delay Tmax.
Oral bioavailability is approximately 53% after a single dose, with no significant food effect. Bioavailability may be higher under steady-state conditions due to saturation of first-pass metabolism.
For GFR <30 m L/min: initial dose 10 mg/day; maximum 40 mg/day. Hemodialysis: no supplemental dose needed.
No dose adjustment required for mild to moderate renal impairment (Cr Cl ≥20 m L/min). Avoid use in severe renal impairment (Cr Cl <20 m L/min) due to lack of data.
Child-Pugh Class A or B: initial dose 10 mg/day; maximum 40 mg/day. Child-Pugh Class C: not recommended.
Child-Pugh Class A: no dose adjustment; Child-Pugh Class B: reduce dose by 50% (start 25 mg/day, titrate cautiously); Child-Pugh Class C: contraindicated.
Not approved for patients <18 years; off-label use for OCD in children 7–17 years: starting 10 mg/day, titrate by 10 mg/week to target 20–50 mg/day (max 60 mg/day).
Children (8-17 years): start 25 mg orally once daily at bedtime; increase by 25 mg increments every 4-7 days to target dose; for OCD: 25-200 mg/day; maximum 200 mg/day. Weight not routinely used; dosing based on age and response.
Initial dose 10 mg/day; maximum 40 mg/day. Increase in 10 mg increments at intervals of at least 1 week.
Start 25 mg orally once daily at bedtime; titrate slowly (increases of 25 mg every 1-2 weeks); usual maximum 200 mg/day due to increased sensitivity and risk of hyponatremia.
Antidepressants increased the risk of suicidal thinking and behavior (suicidality) in short-term studies in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders. Monitor closely for clinical worsening, suicidality, or unusual changes in behavior. Paroxetine is not approved for use in pediatric patients.
Increased risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.
Suicidality risk in children, adolescents, and young adults,Serotonin syndrome (potentially life-threatening) when co-administered with other serotonergic drugs,MAOI interaction (at least 14-day washout period),Discontinuation syndrome (dizziness, sensory disturbances, anxiety, etc.) upon abrupt withdrawal,Increased risk of bleeding (especially with NSAIDs, aspirin, or anticoagulants),Activation of mania/hypomania in patients with bipolar disorder,Seizure risk (use caution in patients with seizure disorders),Angle-closure glaucoma (pupillary dilation risk),Hyponatremia (elderly, volume-depleted patients),Bone fracture risk (epidemiological studies),Fetal harm (epidemiological data suggest increased risk of cardiovascular malformations, particularly ventricular outflow obstructions, with first-trimester exposure; consider risk/benefit)
Suicidality risk in young patients,Serotonin syndrome,Activation of mania/hypomania,Seizure risk,Abnormal bleeding,Angle-closure glaucoma,Hyponatremia,QT prolongation,Sexual dysfunction,Discontinuation syndrome
Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing an MAOI,Concurrent use of pimozide or thioridazine (QT prolongation and pharmacokinetic interaction),Hypersensitivity to paroxetine or any component of the formulation
Concomitant use with MAOIs,Concomitant use with triptans,Hypersensitivity to fluvoxamine or any excipient,Pregnancy (relative)
No significant food interactions; may be taken with or without food. Grapefruit juice does not interact. Avoid excessive alcohol.
Avoid grapefruit juice as it inhibits CYP1A2 and can increase fluvoxamine serum concentrations, leading to toxicity. No other significant food interactions; however, taking with food may reduce GI upset.
First trimester: Risk of congenital cardiac defects (primarily ventricular and atrial septal defects) with relative risk ~1.5-1.7; persistent pulmonary hypertension of the newborn (PPHN) risk increased ~2-fold; overall absolute risk <.5% for major malformations. Second/third trimester: Risk of preterm delivery, low birth weight, neonatal serotonin discontinuation syndrome (irritability, feeding difficulties, respiratory distress, tremors).
First trimester: Increased risk of congenital malformations, particularly cardiac defects (RR ~1.5-2) based on observational studies; also associated with persistent pulmonary hypertension of the newborn (PPHN) (OR 2.1). Second/third trimester: Late pregnancy exposure may increase risk of preterm birth, low birth weight, and neonatal adaptation syndrome (e.g., respiratory distress, feeding difficulties, irritability).
Paroxetine is excreted into breast milk with an estimated infant dose of ~1% of maternal weight-adjusted dose; M/P ratio is approximately 0.56. Cases of irritability, poor feeding, and drowsiness in breastfed infants have been reported; cautious use recommended, with monitoring for adverse effects.
Fluvoxamine is excreted into breast milk; M/P ratio ranges from 0.29 to 0.59. Relative infant dose is approximately 1.7% of maternal weight-adjusted dose. Low risk of adverse effects in breastfed infants; monitor for drowsiness, poor feeding, and weight gain. AAP classifies as compatible with breastfeeding.
Increased plasma volume and hepatic metabolism in pregnancy may reduce paroxetine levels; consider upward dose titration (20-40% increase) in second and third trimesters based on clinical response; monitor for worsening depression; taper gradually postpartum to avoid discontinuation syndrome.
Plasma levels of fluvoxamine may decrease during pregnancy due to increased volume of distribution and enhanced hepatic metabolism. Dose adjustment may be necessary; consider therapeutic drug monitoring to maintain efficacy. Usually, dose can be increased by 50-100% in third trimester, with gradual reduction postpartum to pre-pregnancy levels.
Paroxetine has a short half-life and is associated with significant withdrawal syndrome upon abrupt discontinuation; taper slowly. It is the most anticholinergic SSRI, causing more constipation, dry mouth, and sedation. Use with caution in elderly due to hyponatremia risk. It is also a weak inhibitor of CYP2D6, potentially increasing levels of co-administered drugs like tamoxifen or metoprolol.
Luvox (fluvoxamine) is a selective serotonin reuptake inhibitor (SSRI) approved for obsessive-compulsive disorder (OCD) and social anxiety disorder. It has a short half-life (15-22 hours) and no active metabolites, making it suitable for patients with hepatic impairment. Monitor for serotonin syndrome, especially when co-prescribed with other serotonergic agents. Luvox is a potent inhibitor of CYP1A2, affecting metabolism of drugs like clozapine, olanzapine, theophylline, and tizanidine. Titrate slowly; start at 50 mg nightly and increase by 50 mg every 4-7 days to a max of 300 mg daily (divided for doses >100 mg). Discontinuation syndrome is common; taper gradually.
Take exactly as prescribed; do not stop suddenly or change dose without consulting doctor.,May cause drowsiness; avoid driving until you know how you react.,Avoid alcohol while taking this medication.,Notify doctor if you experience serotonin syndrome symptoms: agitation, hallucinations, fast heartbeat, fever, muscle stiffness, nausea, diarrhea.,Inform all healthcare providers you are taking paroxetine, especially before surgery or any new medication.,Do not take with MAOIs or within 14 days of stopping MAOIs.
Take Luvox exactly as prescribed, usually once daily at bedtime to minimize daytime drowsiness.,It may take several weeks to feel the full effect; do not stop abruptly without consulting your doctor.,Avoid grapefruit juice, which can increase Luvox levels and side effects.,Report any signs of serotonin syndrome (hallucinations, agitation, rapid heart rate, fever, muscle stiffness) immediately.,Do not drive or operate heavy machinery until you know how Luvox affects you, as it can cause drowsiness or dizziness.,Limit alcohol consumption; alcohol can worsen sedation and increase risk of side effects.,Store at room temperature, away from moisture and heat.
No interactions on record
"Tetracycline may inhibit the metabolism of Fluvoxamine via cytochrome P450 enzyme interference, leading to increased Fluvoxamine plasma concentrations. This elevation potentiates serotonergic effects and may precipitate serotonin syndrome, characterized by hyperthermia, autonomic instability, and neuromuscular abnormalities. Concurrent use requires careful monitoring for signs of toxicity such as agitation, confusion, and tachycardia."
"Dexlansoprazole, a proton pump inhibitor (PPI), may inhibit CYP1A2, the primary enzyme responsible for metabolizing fluvoxamine, a selective serotonin reuptake inhibitor (SSRI). This interaction can lead to increased plasma concentrations of fluvoxamine, potentiating its serotonergic effects and risk of dose-dependent adverse events such as nausea, somnolence, and serotonin syndrome. Clinicians should monitor for signs of fluvoxamine toxicity and consider dose adjustment when initiating or discontinuing dexlansoprazole."
"Afatinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, and fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), both undergo metabolism via CYP450 enzymes. Afatinib is a moderate inhibitor of CYP2D6 and may also inhibit CYP1A2 and CYP3A4, while fluvoxamine is a known inhibitor of CYP1A2 and CYP2C19. Coadministration can lead to increased fluvoxamine concentrations due to inhibition of its metabolism, potentially resulting in enhanced serotonergic effects such as serotonin syndrome, as well as increased adverse effects like nausea, dizziness, or QT prolongation."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about PAXIL vs LUVOX, answered by our medical review team.
PAXIL is a SSRI Antidepressant that works by Paroxetine is a selective serotonin reuptake inhibitor (SSRI) that potentiates serotonergic activity in the central nervous system by inhibiting the reuptake of serotonin (5-HT) from the synaptic cleft, leading to increased serotonin levels.. LUVOX is a SSRI Antidepressant that works by Selective serotonin reuptake inhibitor (SSRI); increases serotonergic activity by blocking reuptake of serotonin into presynaptic neurons.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between PAXIL and LUVOX depend on the specific clinical indication. These are both SSRI Antidepressant agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of PAXIL is: 20 mg orally once daily, typically in the morning; may be increased in 10 mg/day increments at intervals of at least 1 week to a maximum of 50 mg/day.. The standard adult dose of LUVOX is: Initial dose 50 mg orally once daily at bedtime, titrated by 50 mg increments every 4-7 days to effective dose; usual therapeutic range 100-300 mg/day divided once daily (at bedtime) or twice daily if tolerated. Maximum dose 300 mg/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between PAXIL and LUVOX in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. PAXIL is classified as Category C. First trimester: Risk of congenital cardiac defects (primarily ventricular and atrial septal defects) with relative risk ~1.5-1.7; persistent pulmonary hypertension of the newborn . LUVOX is classified as Category C. First trimester: Increased risk of congenital malformations, particularly cardiac defects (RR ~1.5-2) based on observational studies; also associated with persistent pulmonary hype. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.