What to Know About Fluoxetine

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 psychotherapy and lifestyle modification. 

Fluoxetine is approved for treating:

• Major depressive disorder: Adults and children age 8 and older 
• Obsessive-compulsive disorder (OCD): Adults and children ages 7 and older 
• Bulimia nervosa: Adults age 18 and older 
• Panic disorder: Adults age 18 and older 

These conditions are associated with low serotonin levels or altered serotonin metabolism. Serotonin is a neurotransmitter that affects mood, anxiety, and a variety of functions. 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.2 The medication may also have other actions that play a role in its therapeutic effect. 

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

Off-Label Uses

Fluoxetine is sometimes used for conditions that it is not specifically FDA-approved for. These include a variety of mood, anxiety, sexual, and eating disorders.

Before Taking

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

You should not take fluoxetine if it 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: There is an increased risk of suicidal ideation associated with fluoxetine, particularly in children, adolescents, and young adults.
• 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.
• Glaucoma: This medication can exacerbate certain types of 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

Prozac is available in a variety of strengths and preparations, including 10mg, 20mg,40mg, and 60mg pills and as an oral solution. Below are fluoxetine manufacturers' recommended doses, although your healthcare provider may start you on a lower dose and build up to a different target dose depending on your individual circumstances.

Modifications 

If you have liver disease, your healthcare provider 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 healthcare provider 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 healthcare provider 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.

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 an MAOI and beginning fluoxetine, or for up to six weeks when stopping fluoxetine and starting an MAOI. 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, potentially increasing their levels and adverse side effects.