What to Know About Fluoxetine

Antidepressant That Is a Generic Version of Prozac

Taking a prescription such as fluoxetine can alleviate symptoms of depression

SDI Productions / Getty Images

In This Article

Fluoxetine is a prescription antidepressant that is also used for treating several other psychiatric conditions in children and adults. This medication is taken by mouth and it is available in generic (fluoxetine) and brand (Prozac, Sarafem, Prozac Weekly) formulations.

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) that prolongs the action of the neurotransmitter serotonin. This drug can be highly effective, but it is also associated with several serious adverse effects, such as suicidal thoughts, heart rhythm abnormalities, mania, serotonin syndrome, and more.

Uses

Fluoxetine is prescribed for the treatment of several psychiatric conditions. Generally, when this medication is prescribed, the treatment plan includes other methods of managing the diagnosed conditions, such as counseling and lifestyle modification. 

Fluoxetine is approved for treating:

These conditions are associated with low serotonin levels or altered serotonin metabolism. Serotonin is a neurotransmitter that affects mood. Normally a serotonin transporter (SERT) removes serotonin from nerve endings to modulate serotonin’s effects.

Fluoxetine keeps serotonin active by inhibiting the reuptake of this neurotransmitter by SERT.

The medication may also have other actions that play a role in its therapeutic effect. 

Off-Label Uses

Fluoxetine is not commonly prescribed for other problems besides those that it is approved for.

Preliminary research into the use of fluoxetine for the management of borderline personality disorder has been emerging. Fluoxetine has also been investigated as a potential part of the treatment plan for autism in the research setting.

Before Taking

Fluoxetine must be taken with caution and there are several contraindications. If you are pregnant or breastfeeding, you and your doctor need to consider the risks and benefits of taking this medication. And fluoxetine has not been established as safe for children under age 8 who have depression or for children under age 7 who have OCD.

You should not take fluoxetine if fluoxetine or another SSRI has ever caused you to have an allergic reaction, such as a rash or breathing difficulties.

Precautions and Contraindications 

There are several conditions that can increase your risk of having an adverse effect of fluoxetine.

Conditions that can be associated with adverse effects of fluoxetine include:

  • Serotonin syndrome: If you have had serotonin syndrome in response to any medication in the past, it’s important to know that fluoxetine can trigger this condition. Symptoms of serotonin syndrome include agitation, confusion, diarrhea, and muscle rigidity.
  • Suicidal ideation: If you have had a history of suicidal ideation or have attempted suicide in the past, you should know that there is an increased risk of suicidal ideation associated with fluoxetine.
  • Cardiac arrhythmia: Fluoxetine can lead to irregular heart rhythms, and this is an especially high risk if you already have a predisposition to cardiac arrhythmias. This medication is specifically associated with long QT syndrome, a condition that can cause loss of consciousness or even death.
  • Glaucoma: This medication can exacerbate glaucoma, especially if your glaucoma is untreated. 

Other SSRIs

Fluoxetine is a generic medication. Prozac is a commonly prescribed brand of fluoxetine. Fluoxetine is available as a tablet, and Prozac is available as a tablet, an extended-release tablet, and as an oral solution.

Other SSRIs include Zoloft (sertraline), Paxil (paroxetine), Lexapro (escitalopram), Celexa (citalopram), and others.

Dosage

Fluoxetine comes in 60-milligram (mg) tablets that are scored to be cut in half. The recommended starting dose and target dose is different for each condition and age. You should not increase your dose unless directed to do so by your doctor.

Starting Doses and Manufacturer-Recommended Target Doses for Fluoxetine
Indication Dose
Depression in adults start at 20 mg per day and stay at this target dose (can increase to a maximum of to 80 mg per day)
Depression in children start at 10 mg per day and can increase up to 20 mg per day
OCD in adults start at 20 mg per day and can increase up to 60 mg per day
OCD in children start at 10 mg per day and can increase up to 60 mg per day
Bulimia nervosa 60 mg per day in the morning
Panic disorder start at 10 mg per day with a target dose of 20 mg per day (maximum 60 mg per day)

The manufacturer of generic fluoxetine recommends using another fluoxetine product for initial doses of 10 to 20 mg per day or for doses other than 30 mg or 60 mg.

Prozac, for example, is available in 10 mg, 20 mg, and 40 mg tablets or as an oral solution that contains 20 mg per 5 milliliters (mL) of fluoxetine, which can give more options for adjusting the dose.

Modifications 

If you have liver disease, your doctor may prescribe a lower dose of fluoxetine for you than the standard recommended dose for your age and condition. A lower fluoxetine dose is also suggested if you are elderly or if you have multiple medical illnesses. 

How to Take and Store 

Fluoxetine tablets should be stored at a temperature between 68 degrees F to 77 degrees F and kept away from light. It can be taken with or without food.

If you miss a dose, take it as soon as you remember. But if it is nearly time for your next dose, skip the missed dose and only take your next dose at its scheduled time. Never take two doses at the same time.

Side Effects

Fluoxetine is generally a safe medication, but it may cause side effects, some of which can be dangerous or life-threatening. 

Common 

Be sure to call your doctor if you experience side effects of fluoxetine. According to the manufacturer, the most common side effects of fluoxetine are:

  • Abnormal dreams or insomnia 
  • Anorexia (decreased appetite or reduced eating) or nausea 
  • Nervousness or anxiety
  • Dry mouth 
  • A rash 
  • Tiredness or yawning 
  • Sweating 
  • A tremor 
  • General weakness 
  • Diarrhea 
  • Indigestion or heartburn 
  • Flu syndrome, sinusitis, or a sore throat 
  • Abnormal ejaculation or impotence
  • Diminished libido
  • Low blood pressure 

Severe 

Some side effects of fluoxetine are dangerous for your health. You should not abruptly stop taking the medication if you develop severe side effects, but you should get urgent medical attention. 

Serious side effects of fluoxetine include:

  • Suicidal thoughts 
  • Serotonin syndrome 
  • Seizures 
  • Mania 
  • Bleeding 
  • Angle closure glaucoma
  • Long QT syndrome
  • Hyponatremia
  • Severe weight loss 

Warnings and Interactions

It is best not to stop taking fluoxetine abruptly. You should talk to your doctor about a schedule for discontinuing fluoxetine if you plan to stop taking it. You can experience dizziness, balance problems, or mood disruption when you stop taking fluoxetine.

Black Box Warning

Fluoxetine has a black box warning for suicidal thoughts and behaviors in children, adolescents, and young adults. They should be monitored for the emergence or worsening suicidal thoughts and behaviors.

Drug interactions include:

  • Other serotonergic drugs: Fluoxetine can interfere with the action of other medications that interact with serotonin, and the combination can lead to an increased risk of serotonin syndrome. 
  • Pimozide and thioridazine: Fluoxetine can increase the levels of pimozide and thioridazine. Also, if fluoxetine is taken with either of these medications, the combination can increase the risk of a prolonged QT interval.
  • Haloperidol and clozapine: Fluoxetine can raise the levels of these antipsychotic medications.
  • Phenytoin and carbamazepine: Fluoxetine can raise the levels of these anti-seizure medications.
  • Monoamine oxidase inhibitors (MAOIs): MAOIs antidepressants work differently from SSRIs. If you are switching between an MAOI and fluoxetine, you will need a break of about two weeks between stopping one medication and starting the other. Having both in your system can increase the risk of serotonin syndrome.
  • Tricyclic antidepressants (TCAs): These antidepressant levels can be altered when they are taken together or when one is started within a few weeks of stopping the other. 
  • Diazepam and alprazolam: These antianxiety medications can interact with fluoxetine, and the combination may cause psychiatric symptoms.
Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Fluoxetine label. Updated January 2017.

  2. Lazarevic V, Mantas I, Flais I, Svenningsson P. Fluoxetine suppresses glutamate- and GABA-mediated neurotransmission by altering SNARE complex. Int J Mol Sci. 2019;20(17):4247. doi:10.3390/ijms20174247

  3. Stoffers J, Völlm BA, Rücker G, Timmer A, Huband N, Lieb K. Pharmacological interventions for borderline personality disorder. Cochrane Database Syst Rev. 2010;(6):CD005653. doi:10.1002/14651858.CD005653.pub2

  4. Mouti A, Reddihough D, Marraffa C, et al. Fluoxetine for Autistic Behaviors (FAB trial): study protocol for a randomized controlled trial in children and adolescents with autism. Trials. 2014;15:230. doi:10.1186/1745-6215-15-230

  5. Food and Drug Administration. Prozac label.

  6. Al Zaabi MSR, Sridhar SB, Tadross TM. Assessment of incidence, causality, severity, and preventability of suspected adverse drug reactions to antidepressant medications in a psychiatry outpatient setting of a secondary care hospital. J Pharm Bioallied Sci. 2020;12(2):131-138. doi:10.4103/jpbs.JPBS_196_19

Related Articles