Fluoxetine (Prozac)

This article provides an overview of fluoxetine, including the possible benefits, how it works, indications, side effects, and drug interactions.

Key Takeaways

• Fluoxetine is an SSRI, which is a type of antidepressant medication. It works by increasing levels of serotonin in the brain, along with other benefits, such as improved nerve cell health and brain plasticity.
• Fluoxetine is primarily used for depressive and anxiety disorders, but it can be used for several other conditions as well. The exact dose depends on the specific use, the individual’s age, and other factors.
• There are many possible side effects and drug interactions when using fluoxetine, some of which may be severe. It is only available as a prescription and should be taken under medical supervision.

Fluoxetine Overview

Fluoxetine is a prescription antidepressant that falls under the category of selective serotonin reuptake inhibitors (SSRIs). It was developed in the 1970s and first approved for use in 1987, making it one of the oldest SSRIs in mental health treatment. Like other SSRIs, it affects levels of serotonin in the brain, which is thought to play a large role in its antidepressant properties. ^{[1] [2]}

Brand Names

The most common brand name for fluoxetine is Prozac. Other brand names for fluoxetine include:

• Sarafem®
• Prozac Weekly®
• Selfemra®
• Rapiflux®

How Does Fluoxetine Work?

Individuals with depression have been shown to have low levels of serotonin in the cerebrospinal fluid (CSF). This is important since serotonin is a neurotransmitter involved in mood, sleep, appetite, and sexual function. Fluoxetine primarily works by blocking the reuptake of serotonin by nerve cells, which allows more serotonin to be freely available in the brain and body. ^{[2] [3]}

Later research has found that the benefits of fluoxetine likely extend beyond mere modulation of serotonin. For example, fluoxetine also promotes brain plasticity (structural and functional brain changes), may help combat inflammation and oxidative stress, and promotes brain-derived neurotrophic factor (BDNF) and healthy nerve cell function.

When is it prescribed?

Fluoxetine is prescribed for moderate to severe mental health concerns. It is FDA-approved for the treatment of: ^{[2] [3]}

• Major depressive disorder (MDD) (8 years and older)
• Obsessive-compulsive disorder (OCD) (7 years and older)
• Panic disorder
• Bulimia nervosa
• Depressive episodes in bipolar I disorder (when used with olanzapine)
• Treatment-resistant depression (when used alongside olanzapine)

Fluoxetine is also often prescribed off-label for other conditions, such as: ^{[2] [4]}

• Binge eating disorder (BED)
• Social anxiety disorder (SAD)
• Premenstrual dysphoric disorder (PMDD)
• Borderline personality disorder (BPD)
• Raynaud’s syndrome
• Selective mutism

What to Know Before Taking Fluoxetine

There are several things to be aware of before taking fluoxetine. While it can be beneficial for many individuals, it’s important to understand the dosing, precautions, side effects, and general safety information.

Dosage

Fluoxetine is taken orally. It can come as an oral solution (5mg/ 20mL), tablet (10, 20, and 60mg), capsule (10, 20, and 40mg), and a delayed-release capsule (90mg). ^[2]

The most common dose of fluoxetine is 20 mg once per day, either in the morning or evening. Individuals who experience more side effects may start with a lower dose of 10mg. However, the most effective dose is generally between 20 to 40mg for most people. ^[2]

Listed below are the doses used for specific conditions in adults: ^[2]

• MDD: Starting dose of 20 mg and maximum daily dose of 80mg
• OCD: Starting dose of 20 mg and maintenance dose of 20-60 mg once daily
• Bulimia nervosa: 60 mg, but only if minimal or no response to psychotherapy after 6 weeks
• Panic disorder: Starting dose of 10 mg, possibly increased to 20 mg after one week. And a maximum dose of 60 mg daily

Fluoxetine can also be used in children over 8 with MDD and children over 7 with OCD. The dose for both of these situations is 10 mg daily. ^[2]

Precautions

There are several precautions with fluoxetine, such as individuals with liver or kidney issues, pregnant or breastfeeding women, individuals with bipolar disorder, children, and older adults. Specific precautions include: ^{[2] [4] [5]}

• Individuals with liver cirrhosis or other metabolic issues that decrease the clearance of fluoxetine should use a lower and/or less frequent dose.

• Individuals with kidney impairment may not need to adjust the dose. However, once-weekly dosing may be better for people on hemodialysis.

• Fluoxetine may cause adverse pregnancy effects. It is recommended to taper off fluoxetine during the third trimester. Some cases may require tapering as soon as the second trimester to minimize adverse effects.

• Fluoxetine is not recommended for breastfeeding women since it is excreted in breast milk.

• Some individuals with bipolar disorder may experience mania or hypomania after starting fluoxetine.

• Children and older adults may be more sensitive to the effects of fluoxetine, which requires lower doses. 10mg is the approved dose for children with MDD and OCD, and 10 to 20mg is the recommended dosage range for older adults.

Side Effects

Fluoxetine has several side effects. Most of these are mild, but some can be severe or even life-threatening. The risk of side effects increases at higher doses.

Fluoxetine can affect everyone differently, so it’s important to watch for any unusual effects or changes after you start taking fluoxetine. If these occur, talk with your doctor as soon as possible.

Common Side Effects

Common side effects of fluoxetine include: ^{[2] [3] [4] [5]}

• Insomnia
• Diarrhea
• Nausea
• Abnormal dreams
• Dry mouth
• Anorexia
• Headache
• Drowsiness
• Anxiety
• Nervousness
• Yawning
• Bruising
• Seizures
• Changes in weight
• Muscle weakness
• Delayed orgasm (or no orgasm)
• Decreased libido
• Hyperhidrosis (excessive sweating)
• Sore throat
• Tremors

Most of these side effects are temporary and diminish or resolve after one to several weeks, as your body adjusts to the medication. However, sexual side effects, such as delayed orgasm, often do not decrease over time. ^{[2] [4]}

Rare and Severe Side Effects

Other side effects of fluoxetine happen much less frequently. Some of these may be severe.

Rare side effects of fluoxetine include: ^{[2] [3] [4] [5]}

• Low sodium levels
• Teeth grinding
• Suicidal thoughts (especially in children, adolescents, and young adults under 25\)
• Angle closure glaucoma
• Seizure
• Heart rhythm abnormalities (such as QT prolongation)
• Bleeding
• Low bone mineral density
• And increased risk of fractures
• Allergic reactions and rash
• Impaired cognitive function

Serotonin Syndrome

Another possible and potentially serious side effect of fluoxetine is serotonin syndrome. This occurs when too much serotonin builds up in the brain and body. Symptoms of serotonin syndrome include nervousness, dilated pupils, nausea, diarrhea, muscle tightness or spasms, and confusion. ^{[2] [4]}

If left untreated, it can lead to severe symptoms, such as seizures, high fever, delirium, rapid heart rate, coma, and elevated blood pressure. It can be fatal in some cases. ^[4]

Drug Interactions with Fluoxetine

Fluoxetine has several possible drug interactions to be aware of. For example, fluoxetine inhibits an enzyme responsible for metabolizing certain drugs, especially: ^{[2] [4]}

• Tricyclic antidepressants:
• Antipsychotics
• Antiarrhythmic medications
• Benzodiazepines
• Anticonvulsants
• Monoamine oxidase inhibitors (MAOIs)

Therefore, taking any of these medications alongside fluoxetine can increase their concentration and effects in the body. This may lead to an increased risk of side effects, such as sedation with benzodiazepines, or increased QT interval with antiarrhythmic medications. ^[2]

Fluoxetine also increases the risk of bleeding when combined with warfarin, NSAIDs, and aspirin. The interaction is particularly strong with warfarin. ^{[2] [3]}

Fluoxetine may also interact with other drugs that increase serotonin, which can potentially lead to serotonin syndrome. Examples of other serotonin-enhancing drugs include: ^{[4] [5]}

• St. John’s wort
• Tryptophan
• Tricyclic antidepressants
• MAOIs
• Other antidepressants
• Triptans
• Tramadol
• Lithium
• Illicit drugs, such as fentanyl and amphetamines

In addition, it should never be used with linezolid, pimozide, or thioridazine. ^[2]

For more information, there is a full list of interactions on the Prozac label on the FDA website. ^[5]

Cessation and Withdrawal

Some individuals may reach a point where they can stop taking fluoxetine. Stopping fluoxetine safely requires a carefully laid out plan by your doctor. They will give you a tapering schedule that gradually reduces the dose of fluoxetine you’re taking over time. Typically, the medication dose is reduced by a specific percentage every several weeks, but it depends on the individual and other important factors. ^[3]

You should never stop fluoxetine suddenly or without your doctor’s guidance. Suddenly stopping fluoxetine greatly increases the risk of withdrawal-like symptoms, which can include agitation, confusion, headache, diarrhea, vomiting, restlessness, and rapid heartbeat, among others. It may also increase the risk of suicidal thoughts. ^[5]

When to Stop Taking Fluoxetine

The decision to stop taking fluoxetine depends on a thorough evaluation and consultation with your doctor. It is recommended that most individuals take fluoxetine for at least 6 months to receive the greatest benefits and reduce the risk of returning symptoms. If your doctor has noticed sustained improvement of symptoms during this time, implementing a tapering schedule may be appropriate. ^[6]

Some individuals with chronic depression or other chronic mental health conditions may need to take fluoxetine for much longer, sometimes lifelong.

Also, some individuals may need to stop taking fluoxetine if the side effects outweigh the benefits. In these cases, a new medication or an alternative form of treatment, such as psychotherapy, may be recommended.

Fluoxetine FAQs

Is it safe to drink alcohol while on fluoxetine?

It is generally recommended to avoid drinking alcohol while taking fluoxetine. Talk with your doctor to see if any amount may be okay for your situation.

What is considered a high dose of fluoxetine?

The standard dose of fluoxetine for adults is between 20 to 40mg. Anything above 60mg is generally considered a high dose, with the maximum possible dose set at 80mg.

Is fluoxetine used to treat animals?

Yes, fluoxetine can be used to treat various behavioral issues in animals. It is FDA-approved for separation anxiety in dogs, and can be used off-label for other issues in dogs, cats, and birds.

Author

Jack Cincotta

Jack Cincotta holds a M.S. degree in Psychology. He is also a board-certified holistic health practitioner through AADP and an AFPA-certified holistic health coach and nutritionist.

Activity History - Last updated: March 19, 2026, Published date: March 19, 2026

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Reviewer

David MilesPharmD

David is a seasoned Pharmacist, natural medicines expert, medical reviewer, and pastor.

Activity History - Medically reviewed on March 20, 2026 and last checked on March 19, 2026