Fluoxetine Uses, Dosage, Side Effects, Food Interaction and all others data.

Fluoxetine Hydrochloride is a phenylpropylamine derivative antidepressant for oral administration, it is chemically unrelated to tricyclic, tetracycline or other available antidepressants.

Fluoxetine has been shown to selectively inhibit the reuptake of serotonin (5-HT) at the presynaptic neuronal membrane which causes increased synaptic concentration of serotonin in the CNS. This results in numerous functional changes associated with enhanced serotonergic neurotransmission.

Fluoxetine appears to have no effect on the reuptake of norepinephrine and dopamine and does not exhibit antihistaminic or alpha1 adrenergic blocking activity at usual therapeutic doses.

Fluoxetine blocks the serotonin reuptake transporter in the presynaptic terminal, which ultimately results in sustained levels of 5-hydroxytryptamine (5-HT) in certain brain areas. However, fluoxetine binds with relatively poor affinity to 5-HT, dopaminergic, adrenergic, cholinergic, muscarinic, and histamine receptors which explains why it has a far more desirable adverse effect profile compared to earlier developed classes of antidepressants such as tricyclic antidepressants.

Trade Name Fluoxetine
Availability Prescription only
Generic Fluoxetine
Fluoxetine Other Names Fluoxetin, Fluoxetina, Fluoxétine, Fluoxetine, Fluoxetinum
Related Drugs Rexulti, sertraline, trazodone, alprazolam, clonazepam, Lexapro, amitriptyline, venlafaxine, Zoloft, citalopram
Weight 20mg,
Type Capsule
Formula C17H18F3NO
Weight Average: 309.3261
Monoisotopic: 309.134048818
Protein binding

Approximately 94% of fluoxetine is plasma protein bound.

Groups Approved, Vet approved
Therapeutic Class Phenothiazine related drugs
Manufacturer Albion Pharmaceuticals Ltd, Endo Ventures Limited, Mersifarma Tirmaku Mercusana
Available Country Bangladesh, United Kingdom, United States, Netherlands, Indonesia
Last Updated: September 19, 2023 at 7:00 am


Fluoxetine is used for-

  • Depressive illness
  • Bulimia nervosa and anorexia nervosa
  • Obsessive compulsive disorders
  • Pre-menstrual syndrome

Fluoxetine is also used to associated treatment for these conditions: Alcohol Dependency, Anorexia Nervosa (AN), BMI >30 kg/m2, Bulimia Nervosa, Cataplexy, Depression, Bipolar, Major Depressive Disorder (MDD), Myoclonus, Obsessive Compulsive Disorder (OCD), Panic Disorder (With or Without Agoraphobia), Premature Ejaculation, Premenstrual Dysphoric Disorder, Treatment Resistant Depression (TRD)

How Fluoxetine works

The monoaminergic hypothesis of depression emerged in 1965 and linked depression with dysfunction of neurotransmitters such as noradrenaline and serotonin. Indeed, low levels of serotonin have been observed in the cerebrospinal fluid of patients diagnosed with depression. As a result of this hypothesis, drugs that modulate levels of serotonin such as fluoxetine were developed.

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) and as the name suggests, it exerts it's therapeutic effect by inhibiting the presynaptic reuptake of the neurotransmitter serotonin. As a result, levels of 5-hydroxytryptamine (5-HT) are increased in various parts of the brain. Further, fluoxetine has high affinity for 5-HT transporters, weak affinity for noradrenaline transporters and no affinity for dopamine transporters indicating that it is 5-HT selective.

Fluoxetine interacts to a degree with the 5-HT2C receptor and it has been suggested that through this mechanism, it is able to increase noradrenaline and dopamine levels in the prefrontal cortex.


Fluoxetine dosage

Initial treatment: Recent studies suggest that 20 mg/day of Fluoxetine may be sufficient to obtain satisfactory antidepressant response. Consequently, a dose of 20 mg/day administered in the morning is recommended as the initial dose.

A dose increase may be considered after several weeks if no clinical improvement is observed. Dosage above 20 mg/day, should be administered on a bid schedule (i.e. morning and noon) and should not exceed a maximum dose of 80 mg/day. As with other antidepressants, the full antidepressant effect may be delayed until 4 weeks of treatment or longer. As with many other medications, a lower or less frequent dosage should be used in patients with renal and/or hepatic impairment.

A lower or less frequent dosage should also be considered for patients, such as elderly, with concurrent disease or on multiple medication. A recommended maximum dose for elderly patients is 60 mg per day.

Maintenance treatment: It is generally agreed among expert psychopharmacologists that acute episode of depression requires several months or longer sustained pharmacologic therapy. Fluoxetine is also used in dosage of 60 mg daily for the management of bulimia nervosa.

Side Effects

Gastrointestinal: Nausea, vomiting, dyspepsia, dry mouth, and diarrhoea.

Neurological: Anxiety, nervousness, insomnia/ drowsiness and fatigue.

Others: Excessive sweating, pruritus, skin rashes associated with liver, kidney and lung involvement. It has therefore been advised that Fluoxetine therapy should be discontinued in any patient who develops a skin rash.


In a report that included 234 fluoxetine overdose cases, it was concluded that symptoms resulting from fluoxetine overdose were generally minor and short in duration. The most common overdose adverse effects included drowsiness, tremor, tachycardia, nausea and vomiting, and providing the patient with aggressive supportive care was the recommended intervention.

Despite this evidence, more severe adverse effects have been linked to fluoxetine ingestion although most of these reports involved co-ingestion with other substances or drugs as well as other factors. For example, there is a case report that details a patient who ingested 1400 mg of fluoxetine in a suicide attempt and as a result, experienced a generalized seizure three hours later. In a separate case, a 14 year old patient ingested 1.2 g of fluoxetine and subsequently experienced tonic/clonic seizures, symptoms consistent with serotonin syndrome, and rhabdomyolysis, although the patient did not experience sustained renal injury.


As Fluoxetine undergoes hepatic metabolism and renal excretion, it should be used with caution and in reduced doses in patients with impaired hepatic or renal function. Because of its epileptogenic effect, it should be used with caution in patients with epilepsy or a history of such disorders. Fluoxetine may alter glycaemic control and therefore caution is also warranted in diabetic subjects. Depressed patients with suicidal tendencies should be carefully supervised during treatment. Fluoxetine is not usually considered a suitable form of therapy for the depressive component of bipolar (manic depressive) illness as mania may be precipitated.


May lead to serotonin syndrome with serotonergic drugs (e.g. triptans, TCAs, fentanyl, tramadol, lithium, buspirone, tryptophan). May increase risk of bleeding with aspirin, NSAIDs, warfarin and other anticoagulants. May increase plasma levels of phenytoin.

Potentially Fatal: May increase risk of serotonin syndrome with concomitant admin or within 14 days of MAOIs withdrawal. May increase the QTc prolonging effect of pimozide and thioridazine.

Food Interaction

  • Avoid alcohol.
  • Take with or without food.

[Moderate] GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents.

Use in combination may result in additive central nervous system depression and
MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol.

Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

Volume of Distribution

The volume of distribution of fluoxetine and it's metabolite varies between 20 to 42 L/kg.

Elimination Route

The oral bioavailability of fluoxetine is 13

In a bioequivalence study, the Cmax of fluoxetine 20 mg for the established reference formulation was 11.754 ng/mL while the Cmax for the proposed generic formulation was 11.786 ng/ml.

Fluoxetine is very lipophilic and highly plasma protein bound, allowing the drug and it's active metabolite, norfluoxetine, to be distributed to the brain.

Half Life

The half life of fluoxetine is significant with the elimination half-life of the parent drug averaging 1-3 days after acute administration, and 4-6 days after chronic administration. Further, the elimination half life of it's active metabolite, norfluoxetine, ranges from 4-16 days after both acute and chronic administration. The half-life of fluoxetine should be considered when switching patients from fluoxetine to another antidepressant since marked accumulation occurs after chronic use. Fluoxetine's long half-life may even be beneficial when discontinuing the drug since the risk of withdrawal is minimized.


The clearance value of fluoxetine in healthy patients is reported to be 9.6 ml/min/kg.

Elimination Route

Fluoxetine is primarily eliminated in the urine.

Pregnancy & Breastfeeding use

Pregnancy: In animal studies, no teratogenicity or harmful effect was found. Because animal reproductive studies are not always predictive of human responses, Fluoxetine should be used in pregnancy only if clearly needed.

Lactation: As Fluoxetine is excreted in human milk, caution should be exercised when Fluoxetine is administered to nursing women.


Fluoxetine Hydrochloride is contraindicated in patients known to be hypersensitive to it.

Monoamine oxidase inhibitors: There have been reports of serious, sometimes fatal reactions (including hyperthermia, rigidity, myoclonus, autonomic instability with possible rapid fluctuations of vital signs and changes of mental status that include extreme agitation progressing to delirium and coma) in patients receiving Fluoxetine in combination with monoamine oxidase inhibitors (MAOIs), and in patients who have recently discontinued Fluoxetine and are then started on MAOIs. Some cases presented with features resembling neuroleptic malignant syndrome. Therefore, Fluoxetine should not be used in combination with MAOI, or within 14 days of discontinuing therapy with MAOI. Since Fluoxetine and its major metabolites have very long elimination half-lives, at least 5 weeks should be allowed after stopping Fluoxetine and before starting MAOI.

Special Warning

Use in children: The use of Fluoxetine in children is not recommended as safety and efficacy have not been established.

Acute Overdose

Symptoms: Nausea, vomiting, seizure, CV dysfunction ranging from asymptomatic arrhythmias to cardiac arrest (including ventricular arrhythmias and nodal rhythm) or ECG changes indicative of QTc prolongation to cardiac arrest, pulmonary dysfunction, signs of altered CNS status ranging from excitation to coma.

Management: Symptomatic and supportive treatment. May admin activated charcoal w/ sorbitol.

Storage Condition

Store between 20-25° C. Protect from light.

Innovators Monograph

You find simplified version here Fluoxetine

Fluoxetine contains Fluoxetine see full prescribing information from innovator Fluoxetine Monograph, Fluoxetine MSDS, Fluoxetine FDA label


What is Fluoxetine used for?

Fluoxetine is a type of antidepressant known as an SSRI (selective serotonin reuptake inhibitor). It is often used to treat depression, and also sometimes obsessive compulsive disorder and bulimia. It is used for the treatment of major depressive disorder, obsessive–compulsive disorder, bulimia nervosa, panic disorder, and premenstrual dysphoric disorder. brans also often prescribe Prozac to treat other types of anxiety as well.

How safe is Fluoxetine?

It is considered safe and effective in treating depression, anxiety, and obsessive compulsive disorder, and bulimia. Adverse effects include an increased risk of suicidal thoughts in some younger people.

How does Fluoxetine work?

Fluoxetine works by blocking the absorption of the neurotransmitter serotonin in the brain.

What are the common side effects of Fluoxetine?

Common side effects of Fluoxetine are include:

  • nervousness
  • anxiety
  • difficulty falling asleep or staying asleep
  • nausea
  • diarrhea
  • dry mouth
  • heartburn
  • yawning
  • weakness
  • uncontrollable shaking of a part of the body
  • loss of appetite
  • weight loss
  • changes in sex drive or ability
  • excessive sweating
  • headache, confusion, weakness, difficulty concentrating, or memory problems

Is Fluoxetine safe during pregnancy?

Fluoxetine is one of the safest antidepressants you can take during pregnancy .

Is Fluoxetine safe during breastfeeding?

A safety scoring system finds Fluoxetine use to be possible during breastfeeding, although others do not recommend its use. If the mother was taking Fluoxetine during pregnancy or if other antidepressants have been ineffective, most experts recommend against changing medications during breastfeeding.

Can I drink alcohol with Fluoxetine?

Alcohol can increase the nervous system side effects of Fluoxetine such as dizziness, drowsiness, and difficulty concentrating. You should avoid or limit the use of alcohol while being treated with Fluoxetine.

Can I drive after taking Fluoxetine?

Fluoxetine might be best to stop driving and cycling for the first few days of treatment until you know how this medicine makes you feel.

When should be taken of Fluoxetine?

Fluoxetine comes as a capsule to take by mouth. Fluoxetine capsules, tablets, and liquid are usually taken once a day in the morning or twice a day in the morning and at noon. Fluoxetine delayed-released capsules are usually taken once a week.

Can I take Fluoxetine on an empty stomach?

Take Fluoxetine once a day. You can take it with or without food. You can take Fluoxetine at any time, as long as you stick to the same time every day. If you have trouble sleeping, it's best to take it in the morning.

How long does Fluoxetine take to work?

It usually takes 4 to 6 weeks for Fluoxetine to work.

How long does Fluoxetine stay in my system?

Fluoxetine stays in the body for 25 days after you stop taking it. Even then, the prescription is only 99 percent out of your system.

Can I take Fluoxetine for a long time?

Fluoxetine is safe to take for a long time. A few people may get sexual side effects, such as problems getting an erection or a lower sex drive. In some cases these can continue even after stopping the medicine. Speak to your doctor if you are worried.

Who should not take Fluoxetine ?

You should not use Fluoxetine if you are allergic to Fluoxetine, if you also take Fluoxetine. Do not use Fluoxetine if you have used an MAO inhibitor in the past 14 days.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.If you miss a dose of Fluoxetine Weekly, take the missed dose as soon as you remember and take the next dose 7 days later. However, if it is almost time for the next regularly scheduled weekly dose, skip the missed dose and take the next one as directed. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention.

Is Fluoxetine safe for heart patients?

Fluoxetine are considered lower risk antidepressants with minimal effects on the cardiovascular system.

When is Fluoxetine contraindicated?

Fluoxetine is contraindicated in those patients with Fluoxetine hypersensitivity or hypersensitivity to any of the formulation components. Avoid abrupt discontinuation of any SSRI if possible.

Does Fluoxetine make me sleep?

Fluoxetine taken for depression or anxiety, can make you feel sleepy.

Can Fluoxetine cause weight gain?

Fluoxetine make gaining weight more likely.

Does Fluoxetine cause hair loss?

Fluoxetine can cause hair loss in a very small minority of patients.

Do Fluoxetine damage my brain?

Fluoxetine seem to cause permanent brain damage.

Can Fluoxetine affect my fertility?

No, there isn't any data to suggest that anti-depressants affect female fertility.

Can Fluoxetine affect my heart?

Fluoxetine induced a statistically significant 6% decrease in heart rate, a 2% increase in supine systolic pressure, and a 7% increase in ejection fraction.

Is Fluoxetine bad for my liver?

Fluoxetine therapy can be associated with transient asymptomatic elevations in serum aminotransferase levels and has been linked to rare instances of clinically apparent acute liver injury.

*** Taking medicines without doctor's advice can cause long-term problems.