Fluoxetine 20mg Tablets
WARNING: Drugs like this one have raised the chance of suicidal thoughts or actions in children and young adults. The risk may be greater in people who have had these thoughts or actions in the past. All people who take this drug need to be watched closely. Call the doctor right away if signs like depression, nervousness, restlessness, grouchiness, panic attacks, or changes in mood or actions are new or worse. Call the doctor right away if any thoughts or actions of suicide occur.This drug is not approved for use in all children. Talk with the doctor to be sure that this drug is right for your child. @ COMMON USES: It is used to treat depression.It is used to treat obsessive-compulsive problems.It is used to treat eating problems.It is used to treat panic attacks.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antidepressant
Pharmacologic Class
Selective Serotonin Reuptake Inhibitor (SSRI)
Pregnancy Category
Category C
FDA Approved
Dec 1987
DEA Schedule
Not Controlled
Overview
What is this medicine?
Fluoxetine is a medication used to treat depression, obsessive-compulsive disorder (OCD), panic attacks, bulimia nervosa, and premenstrual dysphoric disorder (PMDD). It works by helping to restore the balance of a natural substance in the brain called serotonin, which can improve mood, sleep, appetite, and energy levels.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food, and continue taking it even if you feel well. It's essential to adhere to your doctor's or healthcare provider's advice to ensure the best possible outcome.
Storing and Disposing of Your Medication
To maintain the quality and safety of your medication, store it at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep the lid tightly closed and store all medications in a secure location, out of the reach of children and pets.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food, and continue taking it even if you feel well. It's essential to adhere to your doctor's or healthcare provider's advice to ensure the best possible outcome.
Storing and Disposing of Your Medication
To maintain the quality and safety of your medication, store it at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep the lid tightly closed and store all medications in a secure location, out of the reach of children and pets.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take fluoxetine exactly as prescribed, usually once daily in the morning. Do not stop taking it suddenly without talking to your doctor, as this can cause withdrawal symptoms.
- It may take several weeks (4-6 weeks or longer) to feel the full benefits of this medication. Continue taking it even if you don't feel better right away.
- Avoid alcohol while taking fluoxetine, as it can worsen side effects like drowsiness and dizziness.
- Be cautious when driving or operating machinery until you know how this medication affects you, as it may cause dizziness or drowsiness.
- Inform your doctor about all other medications, supplements, and herbal products you are taking, especially St. John's Wort, as serious interactions can occur.
- Report any new or worsening symptoms, especially changes in mood, behavior, or thoughts of self-harm, to your doctor immediately.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
20 mg orally once daily in the morning for Major Depressive Disorder (MDD)
Dose Range:
10 - 80 mg
Condition-Specific Dosing:
Major Depressive Disorder (MDD):
Initial: 20 mg/day, may increase after several weeks to 40 mg/day. Max: 80 mg/day.
Obsessive-Compulsive Disorder (OCD):
Initial: 20 mg/day, may increase to 20-60 mg/day. Max: 80 mg/day.
Bulimia Nervosa:
60 mg/day in the morning.
Panic Disorder:
Initial: 10 mg/day, may increase to 20-60 mg/day. Max: 60 mg/day.
Premenstrual Dysphoric Disorder (PMDD):
Continuous: 20 mg/day. Intermittent: 20 mg/day starting 14 days prior to menstruation through first full day of menses.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
MDD (8-17 years): Initial 10-20 mg/day. OCD (7-17 years): Initial 10 mg/day, may increase to 20 mg/day after 2 weeks, then up to 60 mg/day.
Adolescent:
MDD (8-17 years): Initial 10-20 mg/day. OCD (7-17 years): Initial 10 mg/day, may increase to 20 mg/day after 2 weeks, then up to 60 mg/day.
Dose Adjustments
Renal Impairment:
Mild:
No dose adjustment typically needed.
Moderate:
No dose adjustment typically needed.
Severe:
Use with caution; consider lower doses or less frequent dosing due to potential accumulation of parent drug and metabolites.
Dialysis:
Not well studied; caution advised. Fluoxetine and norfluoxetine are highly protein bound and unlikely to be removed by dialysis.
Hepatic Impairment:
Mild:
Consider lower doses or less frequent dosing (e.g., 10 mg/day or 20 mg every other day).
Moderate:
Consider lower doses or less frequent dosing (e.g., 10 mg/day or 20 mg every other day).
Severe:
Reduce dose by 50% or administer every other day (e.g., 10 mg/day or 20 mg every other day).
Pharmacology
Mechanism of Action
Fluoxetine selectively inhibits the reuptake of serotonin (5-HT) into presynaptic neurons in the central nervous system (CNS), leading to an potentiation of serotonergic neurotransmission. It has minimal affinity for other neurotransmitter receptors (e.g., alpha-adrenergic, beta-adrenergic, dopaminergic, histaminergic, muscarinic, GABAergic).
Pharmacokinetics
Absorption:
Bioavailability:
Not precisely determined, but well absorbed orally.
Tmax:
6-8 hours for fluoxetine; 6-10 hours for norfluoxetine.
FoodEffect:
Food does not significantly affect the extent of absorption, but may delay the rate of absorption slightly.
Distribution:
Vd:
20-45 L/kg (extensive tissue distribution).
ProteinBinding:
Approximately 94.5% (primarily to albumin and alpha-1-glycoprotein).
CnssPenetration:
Yes (readily crosses the blood-brain barrier).
Elimination:
HalfLife:
Fluoxetine: 4-6 days; Norfluoxetine: 4-16 days (due to enterohepatic recirculation).
Clearance:
Highly variable due to extensive metabolism and long half-life.
ExcretionRoute:
Renal (approximately 60% as metabolites), Fecal (approximately 15% as metabolites).
Unchanged:
<10% (fluoxetine); <5% (norfluoxetine) in urine.
Pharmacodynamics
OnsetOfAction:
Initial antidepressant effects may be seen within 1-2 weeks; full therapeutic effects may take 4-6 weeks or longer.
PeakEffect:
Clinical peak effect typically observed after 4-6 weeks of consistent dosing.
DurationOfAction:
Due to long half-lives of fluoxetine and norfluoxetine, effects persist for several weeks after discontinuation.
Safety & Warnings
BLACK BOX WARNING
Antidepressants increased the risk compared to placebo of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults in short-term studies of Major Depressive Disorder (MDD) and other psychiatric disorders. Anyone considering the use of fluoxetine or any other antidepressant in a child, adolescent, or young adult must balance this risk with the clinical need. Short-term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24; there was a reduction in risk with antidepressants compared to placebo in adults aged 65 and older. Depression and certain other psychiatric disorders are themselves associated with increases in the risk of suicide. Patients of all ages who are started on antidepressant therapy should be monitored appropriately and observed closely for clinical worsening, suicidality, or unusual changes in behavior. Families and caregivers should be advised of the need for close observation and communication with the prescriber.
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of low sodium levels, including:
+ Headache
+ Trouble focusing
+ Memory problems
+ Feeling confused
+ Weakness
+ Seizures
+ Changes in balance
Sudden and significant weight gain or loss
Seizures
Dizziness
Slow heartbeat
Unexplained bruising or bleeding
Anxiety
Unusual thirst
Changes in menstrual periods
Increased urination
Trouble controlling body movements
Joint pain
Swollen glands
Painful erection (hard penis) or an erection lasting longer than 4 hours
Sex problems, such as:
+ Decreased interest in sex
+ Trouble having an orgasm
+ Ejaculation problems
+ Difficulty getting or maintaining an erection
If you have any questions or concerns, discuss them with your doctor.
Serious and Potentially Life-Threatening Conditions
A rare but serious condition called serotonin syndrome may occur, especially if you are taking certain other medications. Seek immediate medical attention if you experience:
Agitation
Changes in balance
Confusion
Hallucinations
Fever
Fast or abnormal heartbeat
Flushing
Muscle twitching or stiffness
Seizures
Shivering or shaking
Excessive sweating
Severe diarrhea, stomach upset, or vomiting
Severe headache
Additionally, this medication may cause a type of abnormal heartbeat (prolonged QT interval), which can lead to another type of unsafe abnormal heartbeat (torsades de pointes). Seek immediate medical attention if you experience:
Fast or abnormal heartbeat
Fainting
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it is essential to report any concerns to your doctor. Common side effects include:
Constipation
Diarrhea
Upset stomach
Vomiting
Decreased appetite
Dry mouth
Drowsiness
Strange or vivid dreams
Sleep disturbances
Fatigue or weakness
Flu-like symptoms
Yawning
Hot flashes
Feeling nervous or excitable
Shakiness
Excessive sweating
Headache
* Nose or throat irritation
If you experience any of these side effects or any other concerns, contact your doctor for advice. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of low sodium levels, including:
+ Headache
+ Trouble focusing
+ Memory problems
+ Feeling confused
+ Weakness
+ Seizures
+ Changes in balance
Sudden and significant weight gain or loss
Seizures
Dizziness
Slow heartbeat
Unexplained bruising or bleeding
Anxiety
Unusual thirst
Changes in menstrual periods
Increased urination
Trouble controlling body movements
Joint pain
Swollen glands
Painful erection (hard penis) or an erection lasting longer than 4 hours
Sex problems, such as:
+ Decreased interest in sex
+ Trouble having an orgasm
+ Ejaculation problems
+ Difficulty getting or maintaining an erection
If you have any questions or concerns, discuss them with your doctor.
Serious and Potentially Life-Threatening Conditions
A rare but serious condition called serotonin syndrome may occur, especially if you are taking certain other medications. Seek immediate medical attention if you experience:
Agitation
Changes in balance
Confusion
Hallucinations
Fever
Fast or abnormal heartbeat
Flushing
Muscle twitching or stiffness
Seizures
Shivering or shaking
Excessive sweating
Severe diarrhea, stomach upset, or vomiting
Severe headache
Additionally, this medication may cause a type of abnormal heartbeat (prolonged QT interval), which can lead to another type of unsafe abnormal heartbeat (torsades de pointes). Seek immediate medical attention if you experience:
Fast or abnormal heartbeat
Fainting
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it is essential to report any concerns to your doctor. Common side effects include:
Constipation
Diarrhea
Upset stomach
Vomiting
Decreased appetite
Dry mouth
Drowsiness
Strange or vivid dreams
Sleep disturbances
Fatigue or weakness
Flu-like symptoms
Yawning
Hot flashes
Feeling nervous or excitable
Shakiness
Excessive sweating
Headache
* Nose or throat irritation
If you experience any of these side effects or any other concerns, contact your doctor for advice. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Signs of Serotonin Syndrome: agitation, hallucinations, confusion, fast heartbeat, fever, sweating, shivering, muscle stiffness or twitching, loss of coordination, nausea, vomiting, diarrhea.
- Allergic reaction: rash, hives, swelling of face/lips/tongue/throat, difficulty breathing.
- New or worsening suicidal thoughts or behavior, especially in children, adolescents, and young adults.
- Unusual bleeding or bruising.
- Symptoms of hyponatremia (low sodium): headache, confusion, weakness, unsteadiness, memory problems.
- Symptoms of mania/hypomania: increased energy, racing thoughts, decreased need for sleep, reckless behavior.
- Seizures.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced.
If you are currently taking or have recently taken certain medications, such as:
+ Linezolid, methylene blue, pimozide, or thioridazine
+ Medications for depression or Parkinson's disease, including isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline, within the last 14 days, as this may increase the risk of very high blood pressure
If you are taking any medications that can cause abnormal heart rhythms (prolonged QT interval). There are many medications that can have this effect, so it is crucial to consult with your doctor or pharmacist if you are unsure.
To ensure your safety, it is vital to provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter medications you are taking
Any natural products or vitamins you are using
Your medical history, including any health problems you have
Do not start, stop, or change the dosage of any medication without first consulting your doctor to confirm that it is safe to do so in conjunction with this medication.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction you experienced.
If you are currently taking or have recently taken certain medications, such as:
+ Linezolid, methylene blue, pimozide, or thioridazine
+ Medications for depression or Parkinson's disease, including isocarboxazid, phenelzine, tranylcypromine, selegiline, or rasagiline, within the last 14 days, as this may increase the risk of very high blood pressure
If you are taking any medications that can cause abnormal heart rhythms (prolonged QT interval). There are many medications that can have this effect, so it is crucial to consult with your doctor or pharmacist if you are unsure.
To ensure your safety, it is vital to provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter medications you are taking
Any natural products or vitamins you are using
Your medical history, including any health problems you have
Do not start, stop, or change the dosage of any medication without first consulting your doctor to confirm that it is safe to do so in conjunction with this medication.
Precautions & Cautions
Important Warnings and Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
Caution with Daily Activities
Until you know how this medication affects you, avoid driving and other activities that require alertness.
Stopping the Medication
Do not stop taking this medication abruptly without consulting your doctor, as this may increase your risk of side effects. If you need to stop taking this medication, your doctor will instruct you on how to gradually discontinue it to minimize potential risks.
Interactions with Other Substances
Avoid consuming alcohol while taking this medication. Additionally, consult your doctor before using marijuana, cannabis, or prescription or over-the-counter medications that may cause drowsiness or impair your reactions.
Monitoring Blood Sugar Levels
If you have diabetes, closely monitor your blood sugar levels, as this medication may affect them.
Delayed Onset of Effects
It may take several weeks to experience the full effects of this medication.
Bleeding Risks
This medication may increase the risk of bleeding, which can be life-threatening in some cases. Discuss this risk with your doctor.
Severe Reactions
Rarely, severe and potentially life-threatening reactions, including lung, kidney, or liver problems, have occurred with this medication. Seek immediate medical attention if you experience any of the following symptoms:
- Changes in urine output
- Dark urine
- Decreased appetite
- Upset stomach or stomach pain
- Light-colored stools
- Vomiting
- Yellow skin or eyes
- Shortness of breath
Eye Problems
Some individuals may be at a higher risk of developing eye problems while taking this medication. Your doctor may recommend an eye exam to assess your risk. If you experience any of the following symptoms, contact your doctor promptly:
- Eye pain
- Changes in vision
- Swelling or redness in or around the eye
Low Sodium Levels
This medication can cause low sodium levels, which can be life-threatening and lead to seizures, loss of consciousness, breathing difficulties, or death.
Effects on Growth in Children and Teens
In some cases, this medication may affect growth in children and adolescents. Regular growth checks may be necessary. Discuss this risk with your doctor.
Special Considerations for Older Adults
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
If you are pregnant, plan to become pregnant, or are breastfeeding, inform your doctor. Taking this medication in the third trimester of pregnancy may increase the risk of bleeding after delivery and potentially cause health problems in the newborn. Your doctor will discuss the benefits and risks of taking this medication during pregnancy and breastfeeding.
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
Caution with Daily Activities
Until you know how this medication affects you, avoid driving and other activities that require alertness.
Stopping the Medication
Do not stop taking this medication abruptly without consulting your doctor, as this may increase your risk of side effects. If you need to stop taking this medication, your doctor will instruct you on how to gradually discontinue it to minimize potential risks.
Interactions with Other Substances
Avoid consuming alcohol while taking this medication. Additionally, consult your doctor before using marijuana, cannabis, or prescription or over-the-counter medications that may cause drowsiness or impair your reactions.
Monitoring Blood Sugar Levels
If you have diabetes, closely monitor your blood sugar levels, as this medication may affect them.
Delayed Onset of Effects
It may take several weeks to experience the full effects of this medication.
Bleeding Risks
This medication may increase the risk of bleeding, which can be life-threatening in some cases. Discuss this risk with your doctor.
Severe Reactions
Rarely, severe and potentially life-threatening reactions, including lung, kidney, or liver problems, have occurred with this medication. Seek immediate medical attention if you experience any of the following symptoms:
- Changes in urine output
- Dark urine
- Decreased appetite
- Upset stomach or stomach pain
- Light-colored stools
- Vomiting
- Yellow skin or eyes
- Shortness of breath
Eye Problems
Some individuals may be at a higher risk of developing eye problems while taking this medication. Your doctor may recommend an eye exam to assess your risk. If you experience any of the following symptoms, contact your doctor promptly:
- Eye pain
- Changes in vision
- Swelling or redness in or around the eye
Low Sodium Levels
This medication can cause low sodium levels, which can be life-threatening and lead to seizures, loss of consciousness, breathing difficulties, or death.
Effects on Growth in Children and Teens
In some cases, this medication may affect growth in children and adolescents. Regular growth checks may be necessary. Discuss this risk with your doctor.
Special Considerations for Older Adults
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
If you are pregnant, plan to become pregnant, or are breastfeeding, inform your doctor. Taking this medication in the third trimester of pregnancy may increase the risk of bleeding after delivery and potentially cause health problems in the newborn. Your doctor will discuss the benefits and risks of taking this medication during pregnancy and breastfeeding.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Seizures
- Tachycardia (fast heart rate)
- ECG changes (e.g., QT prolongation)
- Somnolence (drowsiness)
- Coma
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is generally supportive, including maintaining an open airway, monitoring cardiac and vital signs, and managing symptoms. Activated charcoal may be considered if ingested recently.
Drug Interactions
Contraindicated Interactions
- Monoamine Oxidase Inhibitors (MAOIs) (risk of serotonin syndrome)
- Thioridazine (risk of QT prolongation and sudden death)
- Pimozide (risk of QT prolongation and sudden death)
Major Interactions
- Other serotonergic drugs (e.g., triptans, tricyclic antidepressants, fentanyl, lithium, tramadol, buspirone, St. John's Wort) (increased risk of serotonin syndrome)
- Drugs that prolong the QT interval (e.g., Class IA and III antiarrhythmics, antipsychotics, macrolide antibiotics) (additive QT prolongation risk)
- Warfarin and other oral anticoagulants, NSAIDs, aspirin, antiplatelet agents (increased risk of bleeding)
- Drugs metabolized by CYP2D6 (e.g., tricyclic antidepressants, atomoxetine, risperidone, metoprolol, flecainide, propafenone) (fluoxetine is a potent CYP2D6 inhibitor, increasing exposure of these drugs)
- Phenytoin (increased phenytoin levels and toxicity)
- Carbamazepine (increased carbamazepine levels and toxicity)
Moderate Interactions
- Benzodiazepines (e.g., alprazolam, diazepam) (potential for increased benzodiazepine levels)
- Clozapine (increased clozapine levels and adverse effects)
- Metoprolol (increased metoprolol levels)
- Trazodone (increased risk of serotonin syndrome)
- Alcohol (additive CNS depression)
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Psychiatric evaluation (mood, anxiety, suicidal ideation)
Rationale: To establish baseline severity of symptoms and assess risk factors for suicidality.
Timing: Prior to initiation of therapy.
Complete Blood Count (CBC)
Rationale: To assess for any pre-existing hematologic abnormalities, though not routinely affected by fluoxetine.
Timing: Prior to initiation (optional, but good practice).
Liver function tests (LFTs)
Rationale: To assess baseline hepatic function, especially important for dose adjustments in hepatic impairment.
Timing: Prior to initiation.
Renal function tests (creatinine, BUN)
Rationale: To assess baseline renal function, though less critical for dose adjustment than hepatic function.
Timing: Prior to initiation.
Electrolytes (Sodium)
Rationale: To establish baseline, especially in elderly or those on diuretics, due to risk of hyponatremia.
Timing: Prior to initiation.
Weight and Height (pediatric patients)
Rationale: To monitor for potential growth suppression.
Timing: Prior to initiation.
Routine Monitoring
Clinical response and symptom severity (e.g., HAM-D, Y-BOCS scores)
Frequency: Weekly for first 4-6 weeks, then monthly or as clinically indicated.
Target: Reduction in symptom scores, improved mood/function.
Action Threshold: Lack of improvement after adequate trial, worsening symptoms.
Emergence or worsening of suicidal ideation/behavior
Frequency: Weekly for first 4 weeks, then every 2 weeks for next 4 weeks, then monthly for 4 months, then periodically.
Target: Absence of suicidal thoughts or plans.
Action Threshold: Any new or worsening suicidal ideation, agitation, or unusual changes in behavior.
Adverse effects (e.g., GI upset, insomnia, sexual dysfunction, anxiety, agitation)
Frequency: Weekly for first 4-6 weeks, then monthly or as clinically indicated.
Target: Tolerable side effect profile.
Action Threshold: Intolerable side effects, requiring dose adjustment or discontinuation.
Weight (all patients), Height (pediatric patients)
Frequency: Every 3-6 months (weight), annually (height in peds).
Target: Stable weight, normal growth trajectory.
Action Threshold: Significant weight changes, growth suppression in children.
Electrolytes (Sodium)
Frequency: Periodically, especially in elderly or those on diuretics, or if symptoms of hyponatremia develop.
Target: 135-145 mEq/L.
Action Threshold: Sodium < 135 mEq/L or symptomatic hyponatremia.
Symptom Monitoring
- Serotonin Syndrome (agitation, hallucinations, delirium, tachycardia, labile blood pressure, hyperthermia, hyperreflexia, incoordination, nausea, vomiting, diarrhea)
- Neuroleptic Malignant Syndrome (NMS)-like reactions (fever, muscle rigidity, altered mental status, autonomic instability)
- Suicidal ideation or worsening depression/anxiety
- Activation syndrome (insomnia, anxiety, agitation, restlessness)
- Abnormal bleeding or bruising
- Hyponatremia (headache, difficulty concentrating, memory impairment, confusion, weakness, unsteadiness, falls, severe: hallucinations, syncope, seizures, coma)
- Mania/Hypomania (elevated mood, increased energy, decreased need for sleep, racing thoughts, grandiosity)
Special Patient Groups
Pregnancy
Fluoxetine is classified as Pregnancy Category C. Studies in animals have shown adverse effects, and there are no adequate and well-controlled studies in pregnant women. However, human data suggest that exposure to SSRIs, including fluoxetine, during late pregnancy may be associated with an increased risk of persistent pulmonary hypertension of the newborn (PPHN) and neonatal withdrawal symptoms (e.g., respiratory distress, feeding difficulties, irritability, tremor). The decision to use fluoxetine during pregnancy should weigh the potential risks to the fetus against the benefits of treating maternal depression.
Trimester-Specific Risks:
First Trimester:
Limited data, but generally not associated with major congenital malformations. Some studies suggest a small increased risk of cardiac defects, but findings are inconsistent.
Second Trimester:
Generally considered safer than first or third trimester exposure regarding major malformations.
Third Trimester:
Increased risk of persistent pulmonary hypertension of the newborn (PPHN) and neonatal withdrawal syndrome (poor feeding, irritability, tremor, respiratory distress) if exposed late in the third trimester. Monitor neonates for these symptoms.
Lactation
Fluoxetine and its active metabolite, norfluoxetine, are excreted into breast milk. The American Academy of Pediatrics considers fluoxetine to be a drug for which the effect on a nursing infant is unknown but may be of concern. Monitor breastfed infants for irritability, poor feeding, drowsiness, and poor weight gain. Consider alternative antidepressants with lower milk levels or shorter half-lives if possible, or use the lowest effective dose.
Infant Risk:
L3 (Moderate risk) - Monitor infant for adverse effects.
Pediatric Use
Fluoxetine is FDA-approved for MDD in children 8 years and older and OCD in children 7 years and older. A Black Box Warning exists regarding increased risk of suicidal thoughts and behavior in children, adolescents, and young adults. Monitor growth and weight, as SSRIs may be associated with slight growth attenuation. Closely monitor for activation syndrome (anxiety, agitation, insomnia) and emergence of mania/hypomania.
Geriatric Use
Use with caution in elderly patients. Start with lower doses (e.g., 10 mg/day) and titrate slowly. Elderly patients may be more sensitive to the effects of fluoxetine and its long half-life. Increased risk of hyponatremia (low sodium) and falls. Monitor for adverse effects and drug interactions more closely.
Clinical Information
Clinical Pearls
- Fluoxetine has a very long half-life (4-6 days for parent drug, 4-16 days for active metabolite norfluoxetine), which means it takes a long time to reach steady state and to be eliminated from the body. This can be beneficial for adherence (less severe withdrawal if a dose is missed) but requires a long washout period (at least 5 weeks, sometimes longer) before starting MAOIs or other serotonergic drugs.
- It is generally considered a 'more activating' SSRI, which can be helpful for patients with significant fatigue or psychomotor retardation, but may worsen anxiety or insomnia in some individuals, especially at initiation.
- Fluoxetine is a potent inhibitor of CYP2D6, which can lead to significant drug interactions with medications metabolized by this enzyme.
- The 60 mg dose is specifically approved for bulimia nervosa and is often higher than doses used for other indications.
- Prozac Weekly (90 mg delayed-release capsules) is available for once-weekly dosing after patients have been stabilized on daily fluoxetine.
- Monitor for weight changes, as fluoxetine can cause both weight gain and weight loss, though often less associated with significant weight gain compared to some other antidepressants.
Alternative Therapies
- Other Selective Serotonin Reuptake Inhibitors (SSRIs): Sertraline, Escitalopram, Citalopram, Paroxetine, Fluvoxamine
- Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs): Venlafaxine, Duloxetine, Desvenlafaxine
- Atypical Antidepressants: Bupropion, Mirtazapine, Vortioxetine, Vilazodone
- Tricyclic Antidepressants (TCAs): Amitriptyline, Nortriptyline, Imipramine
- Monoamine Oxidase Inhibitors (MAOIs): Phenelzine, Tranylcypromine (reserved for refractory cases)
- Psychotherapy (e.g., Cognitive Behavioral Therapy - CBT)
- Electroconvulsive Therapy (ECT) for severe or refractory depression
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (generic 20mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (for generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure safe use, never share your medication with others or take someone else's medication. This medication is accompanied by a Medication Guide, which provides crucial information for patients. Please read this guide carefully and review it again whenever you receive a refill of this medication. If you have any questions or concerns about this medication, consult with your doctor, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. Be prepared to provide details about the overdose, including the substance taken, the amount, and the time it occurred.