Fluvoxin 100 mg (Fluvoxamine)

Fluvoxin 100mg (Fluvoxamine): Complete Medical Guide — Uses, Dosage, Side Effects & Precautions 

Medically reviewed by Dr. Emily Brown, PharmD, PhD — Pharmaceutical Scientist & Drug Information Specialist. Content verified against current FDA-approved product monographs, DailyMed prescribing labels, and peer-reviewed pharmacological literature. 

BOXED WARNING — Suicidal Thoughts and Behaviors: Antidepressants including fluvoxamine increase the risk of suicidal thinking and behaviour in children, adolescents, and young adults up to age 24 with major depressive disorder and other psychiatric disorders. Patients of all ages started on fluvoxamine should be monitored closely for clinical worsening, suicidality, or unusual changes in behaviour — particularly during the first few months of treatment and following dose changes. Families and caregivers should be advised of the need for close observation and direct communication with the prescriber. This boxed warning is absent from the source content reviewed for this guide. 

Regulatory Note: Fluvoxin 100mg contains Fluvoxamine Maleate 100mg. The originator branded immediate-release product, Luvox, was FDA-approved in 1994 for obsessive-compulsive disorder (OCD). A separate extended-release formulation (Luvox CR) received later FDA approval for both OCD and generalized social anxiety disorder (GSAD), based on distinct clinical trial data. This distinction — between the immediate-release tablet and the extended-release capsule — is critical and is conflated in the source content reviewed, which lists social anxiety disorder as a general indication without specifying which formulation supports it. 

Fluvoxin 100mg is a prescription antidepressant tablet containing Fluvoxamine Maleate 100mg, a selective serotonin reuptake inhibitor (SSRI). At 100mg, this represents either a standard titration step during OCD treatment (following an initial 50mg dose) or, in some prescribing approaches, an alternative starting dose for adult patients — both patterns are reflected in current dosing guidance and are detailed in the Dosage section below. 

A significant accuracy problem in the reviewed source content: It lists OCD, depression, social anxiety disorder, panic disorder, and PTSD as roughly equivalent indications for Fluvoxin 100mg, with no distinction between what is FDA-approved and what is not. This is a meaningful inaccuracy that could lead readers to believe fluvoxamine has broader regulatory backing than it does. The table below sets out the actual approval status of each condition mentioned. 

What Is Fluvoxin 100mg Actually Approved to Treat? — A Reality Check 

Condition	FDA-Approved?	Notes
Obsessive-Compulsive Disorder (OCD)	YES — both formulations	Original 1994 approval (immediate-release); confirmed in extended-release trials
Generalized Social Anxiety Disorder (GSAD)	YES — extended-release (Luvox CR) only	Approved based on 2 positive randomized controlled trials; NOT approved for immediate-release tablets
Major Depressive Disorder	NO in the US (YES in the UK)	Off-label use in the US; approved indication in the United Kingdom
Panic Disorder	NO	Not an FDA-approved indication; off-label use only
Post-Traumatic Stress Disorder (PTSD)	NO	Not an FDA-approved indication anywhere; not supported by the label
COVID-19 (investigational)	NO — investigational only	Studied for anti-inflammatory sigma-1 receptor activity in the ACTIV-6 trial; not an approved use

As the table shows, only OCD is approved across both formulations. Social anxiety disorder approval applies specifically to the extended-release capsule (Luvox CR), based on two positive randomized, double-blind, placebo-controlled trials — one of which enrolled 300 subjects with generalized social anxiety disorder (GSAD) and demonstrated a statistically significant improvement in Liebowitz Social Anxiety Scale (LSAS) scores (P=0.02) compared to placebo over 12 weeks. Depression is approved in the United Kingdom but not in the United States — an important jurisdictional distinction. Panic disorder and PTSD are not FDA-approved indications for fluvoxamine at all, in any formulation, and should be understood as off-label uses at most, requiring individual clinical judgement by a prescriber. 

What is Fluvoxin 100mg? 

Fluvoxin 100mg is a tablet formulation of Fluvoxamine Maleate, belonging to the SSRI class of antidepressants and to a specific chemical series known as 2-aminoethyl oxime ethers of aralkylketones. Following oral administration, fluvoxamine is rapidly and almost completely absorbed from the gastrointestinal tract, though extensive hepatic first-pass metabolism reduces its absolute bioavailability to approximately 53%. Steady-state plasma concentrations are reached after 10–14 days of continuous dosing, and the drug has an elimination half-life of approximately 16 hours 

Beyond its primary serotonin reuptake inhibition, fluvoxamine also has notable affinity for the sigma-1 receptor — a property that has generated research interest, including its investigational (not approved) use during the COVID-19 pandemic for a proposed anti-inflammatory effect via this receptor, studied in the NIH-funded ACTIV-6 trial. This sigma-1 activity has also been proposed as a contributing mechanism in fluvoxamine’s effects on symptoms of psychotic depression, though this remains an area of ongoing research rather than an established, approved use. 

How Does Fluvoxin 100mg Work? 

Mechanism of Action 

Fluvoxamine works by selectively inhibiting the reuptake of serotonin (5-HT) at the presynaptic neuronal membrane, increasing the amount of serotonin available to signal at postsynaptic receptors. Correcting an oversimplification common in consumer content, including the source document: describing this as simply “increasing serotonin levels in the brain” or “reestablishing serotonin balance” glosses over the actual mechanism. Fluvoxamine does not add serotonin to the brain — it blocks the serotonin transporter (SERT) that normally clears serotonin from the synapse after release, prolonging and enhancing the signal of serotonin that is already being naturally released by neurons. 

This is also why fluvoxamine is one of the most potent CYP1A2 enzyme inhibitors among commonly prescribed medications, with meaningful inhibition of CYP2C19, CYP3A4, and CYP2C9 as well. This pharmacological property — entirely absent from the reviewed source content — underlies several serious, FDA-listed drug contraindications discussed below. 

Dosage and Administration of Fluvoxin 100mg 

Dosing for fluvoxamine follows a structured titration protocol based on the original OCD clinical trials, which established efficacy within a 100 to 300 mg/day range: 

Population / Formulation	FDA-Referenced Dosing
Adults — starting dose (immediate-release)	50 mg once daily at bedtime
Adults — alternative starting point at 100mg	100 mg once daily at bedtime; titrate by 50 mg increments every 4–7 days as tolerated
Adults — target/maintenance dose	100–300 mg/day (established efficacy range from OCD trials)
Adults — maximum dose	300 mg/day; doses >100 mg/day given in two divided doses (larger dose at bedtime)
Children/adolescents (8–17 years) — starting dose	25 mg once daily at bedtime
Children/adolescents — titrated range	50–200 mg/day (divided doses if >50 mg/day)
Extended-release (Luvox CR) — starting dose	100 mg once daily at night; titrate 50 mg/week to max 300 mg/day
Elderly / hepatic impairment	Lower starting dose; slower titration

How to Take Fluvoxin 100mg 

• Swallow the tablet whole with a glass of water. Do not crush, chew, or break it 
• Total daily doses above 100mg should be given in two divided doses — if the two doses are unequal, the larger dose should be taken at bedtime 
• May be taken with or without food 
• Take at a fixed time each day for consistency 
• Do not abruptly stop the medication — see Discontinuation Syndrome below 
• Dose increases, when needed, should generally occur no more than every 4 to 7 days, in 50mg increments, until maximum therapeutic benefit is achieved 

Missed Dose 

If a dose is missed, skip it and take the next dose at the usual time. Do not double the dose to compensate. 

Overdose 

Symptoms of fluvoxamine overdose may include drowsiness, nausea, vomiting, dizziness, and — in severe cases — cardiac conduction abnormalities, hypotension, and seizures. Overdose risk is significantly increased when combined with alcohol or other central nervous system depressants. Seek emergency medical attention or contact a poison control centre immediately if an overdose is suspected. 

Discontinuation Syndrome — Why Tapering Matters 

The source content correctly advises against stopping without medical guidance but does not explain the underlying reason. The FDA prescribing label documents that discontinuation-related symptoms have been reported with fluvoxamine and advises against abrupt cessation. These symptoms can include dizziness, sensory disturbances (including electric shock-like sensations), sleep disturbance, agitation, anxiety, nausea, and irritability. Elderly patients may be at increased risk. A gradual dose taper, planned with the prescribing physician, is the recommended approach when discontinuing Fluvoxin 100mg. 

Side Effects of Fluvoxin 100mg 

Common Side Effects 

• Nausea, vomiting, or diarrhoea 
• Headache — often diminishes with continued use 
• Insomnia or drowsiness 
• Sexual dysfunction — decreased libido, anorgasmia, delayed ejaculation 
• Changes in appetite or weight 
• Dry mouth 
• Rhinitis (runny/stuffy nose) 
• Taste perversion (altered taste) 
• Urinary frequency 

In paediatric OCD trials specifically, additional reported effects included agitation, dysmenorrhoea, flatulence, hyperkinesia (increased motor activity), and rash — details specific to the paediatric population that the source content does not address. 

Serious Side Effects — Seek Immediate Medical Attention 

• Suicidal thoughts or behaviour: Particularly relevant in patients under 25 and during the early treatment period or after dose adjustments (see Boxed Warning above). 
• Serotonin syndrome: A potentially life-threatening reaction, especially when fluvoxamine is combined with other serotonergic drugs. Symptoms include agitation, hallucinations, rapid heart rate, fever, muscle rigidity, loss of coordination, and severe gastrointestinal symptoms. Seek emergency care immediately. 
• Abnormal bleeding: SSRIs including fluvoxamine can impair platelet aggregation, increasing bleeding risk, particularly when combined with NSAIDs, aspirin, or anticoagulants. 
• Activation of mania/hypomania: Screening for undiagnosed bipolar disorder is recommended before starting fluvoxamine, as antidepressant monotherapy can precipitate a manic episode. 
• Hyponatraemia: Particularly in elderly patients or those on diuretics; symptoms include headache, confusion, and weakness. 

Drug Interactions — Absolute Contraindications the Source Content Omits 

The source content mentions only that fluvoxamine “may affect” MAOIs and blood thinners, in a single general sentence. This substantially understates a serious and well-documented interaction profile. Fluvoxamine’s potent CYP1A2, CYP2C19, CYP3A4, and CYP2C9 inhibition underlies four absolute drug contraindications specified in the FDA label: 

• Tizanidine — CONTRAINDICATED: Fluvoxamine increases tizanidine’s peak concentration by approximately 12-fold and overall exposure (AUC) by up to 33-fold, causing severe hypotension (blood pressure drops averaging 35 mmHg systolic) and profound sedation. 
• Thioridazine — CONTRAINDICATED: Fluvoxamine raises thioridazine levels, prolonging the QTc interval and increasing the risk of torsades de pointes, a potentially fatal heart rhythm disturbance. 
• Alosetron — CONTRAINDICATED: Fluvoxamine increases alosetron exposure approximately 6-fold and extends its half-life roughly 3-fold. 
• Pimozide — CONTRAINDICATED: Increased pimozide levels raise the risk of QT prolongation and arrhythmia. 
• MAOIs (including linezolid and IV methylene blue) — CONTRAINDICATED: A strict 14-day washout period is required in both directions — do not start fluvoxamine within 14 days of stopping an MAOI, and do not start an MAOI within 14 days of stopping fluvoxamine — due to the risk of serious, sometimes fatal serotonin syndrome. 

Additional clinically significant (though not absolutely contraindicated) interactions  include warfarin (increased plasma concentration and prolonged prothrombin time — requires INR monitoring), theophylline (reduce dose by one-third due to decreased clearance), carbamazepine (elevated levels with toxicity risk), clozapine (significantly raised plasma concentration via CYP1A2 inhibition), and benzodiazepines metabolised by oxidation such as alprazolam, midazolam, and triazolam (reduced clearance — use with caution). 

Precautions and Warnings 

Allergy 

Do not take Fluvoxin 100mg if you have a known hypersensitivity to fluvoxamine or any other SSRI. 

Bipolar Disorder Screening 

Disclose any personal or family history of bipolar disorder, mania, or hypomania before starting treatment. 

Pregnancy — Specific Neonatal Risk Data 

The source content advises a general conversation with your doctor about pregnancy but omits specific documented risk. Infants exposed to immediate-release fluvoxamine late in pregnancy have developed serious adverse reactions including respiratory distress, cyanosis, apnoea, and seizures following delivery, per FDA-referenced clinical data on the extended-release formulation’s labelling. Fluvoxamine (extended-release) has historically been classified as FDA Pregnancy Category C. The decision to continue treatment during pregnancy should weigh the risk of untreated OCD or other psychiatric symptoms against this documented neonatal risk, individualised with your physician. 

Breastfeeding 

Fluvoxamine is secreted in breast milk. It is not absolutely contraindicated in lactating mothers, but the benefits and risks of continuing therapy while breastfeeding should be discussed directly with your healthcare provider. 

Liver Disease and Elderly Patients 

A lower starting dose and slower titration are recommended in patients with hepatic impairment and in elderly patients, given fluvoxamine’s extensive hepatic metabolism. Elderly patients may also be at increased risk of discontinuation symptoms. 

Seizure History and Glaucoma 

Disclose any personal history of seizures or glaucoma (particularly narrow-angle or angle-closure glaucoma) to your prescriber before starting treatment. 

Alcohol 

Avoid or significantly limit alcohol while taking Fluvoxin 100mg, as it can intensify drowsiness, dizziness, and impaired concentration. 

Driving and Operating Machinery 

Fluvoxin 100mg can cause drowsiness, particularly early in treatment. Exercise caution when driving or operating machinery until you know how the medication affects you. 

 Storage Instructions 

• Store in a cool, dry place away from direct sunlight 
• Keep out of reach of children and pets 
• Check the expiry date before use 

Frequently Asked Questions (FAQs) 

What is Fluvoxin 100mg actually approved to treat? 

Fluvoxin 100mg (immediate-release fluvoxamine) is FDA-approved only for obsessive-compulsive disorder (OCD) in adults and children aged 8 and older. Social anxiety disorder approval applies to a different, extended-release formulation (Luvox CR) based on separate clinical trials. Depression, panic disorder, and PTSD are not FDA-approved indications for fluvoxamine in the United States — see the indications table above for full detail. 

How long does it take for Fluvoxin 100mg to work? 

Some improvement may be noticed within 2–4 weeks, but full therapeutic benefit — particularly for OCD — often takes several weeks to a few months of consistent use, alongside gradual dose titration. 

Is Fluvoxin 100mg addictive? 

No, it is not addictive in the sense of substance dependence. However, it should never be stopped abruptly, as this can cause a discontinuation syndrome with symptoms including dizziness, sensory disturbances, and irritability. Always taper under medical guidance. 

Can I take Fluvoxin 100mg with tizanidine or other muscle relaxants? 

No — combining fluvoxamine with tizanidine is absolutely contraindicated due to the risk of severe blood pressure drops and profound sedation. Always give your prescriber and pharmacist a complete list of your current medications. 

Does Fluvoxin 100mg increase suicide risk? 

Like all antidepressants, fluvoxamine carries an FDA boxed warning for increased risk of suicidal thoughts and behaviour in patients under 25, especially during early treatment or after dose changes. Close monitoring by family, caregivers, and the prescriber is essential during this period. 

Is Fluvoxin 100mg safe during pregnancy? 

This requires individualised medical judgement. Documented risks include neonatal complications (respiratory distress, cyanosis, apnoea, seizures) when exposure occurs late in pregnancy. Discuss your specific situation, including the risks of untreated psychiatric symptoms, with your physician. 

Medical Disclaimer 

All information in this guide is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Fluvoxin 100mg is a prescription-only medication and should only be used under the supervision of a licensed healthcare provider. Never self-medicate, adjust your dose, or discontinue this medication without medical guidance. If you or someone you know is experiencing suicidal thoughts, seek immediate help — in the US, call or text 988 (Suicide & Crisis Lifeline) or go to the nearest emergency room. Report suspected adverse effects to the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.