Fluoxetine: Approved Uses, Long-Lasting Effects and Warnings

What fluoxetine is

Fluoxetine is an antidepressant in the group called selective serotonin reuptake inhibitors, or SSRIs. MedlinePlus says it comes as a capsule, a tablet, a delayed-release capsule and a liquid.

This page draws on a current FDA label for generic fluoxetine capsules and on MedlinePlus. It is general information, and it does not replace the Medication Guide that comes with a prescription.

What fluoxetine is approved for, and off-label uses

The label lists fluoxetine for:

• Major depressive disorder, in short-term and maintenance treatment.
• Obsessive-compulsive disorder (OCD), in short-term and maintenance treatment.
• Binge-eating and vomiting behaviors in moderate to severe bulimia nervosa.
• Panic disorder, with or without agoraphobia, in short-term treatment.
• Premenstrual dysphoric disorder (PMDD), on the label for some fluoxetine tablets.

Age limits, the olanzapine combination and PTSD

Fluoxetine is not approved for children under 7. The label says safety and effectiveness are not established under age 8 for depression or under age 7 for OCD. Generalized anxiety disorder and social anxiety disorder are not on the label.

With olanzapine, fluoxetine is approved for depressive episodes in bipolar I disorder and for treatment-resistant depression. The label says fluoxetine alone is not approved for either one. The combination has its own page.

PTSD is off-label for fluoxetine. MedlinePlus says it is sometimes used that way. The VA's National Center for PTSD says only sertraline and paroxetine are FDA-approved for PTSD. It reports insufficient evidence in the 2023 VA/DoD guideline to recommend fluoxetine for or against, and notes it was downgraded from the 2017 guideline.

PMDD is on the FDA label for some fluoxetine tablets, though not on the capsule label. MedlinePlus says fluoxetine is also sometimes used off-label for phobias. Off-label means a use not on the FDA label.

How fluoxetine is thought to work, and why it lingers

The label says the exact way fluoxetine works is unknown, and that it is presumed to be linked to blocking nerve cells from taking serotonin back up. Serotonin is a natural chemical messenger in the brain.

What sets fluoxetine apart on its label is how long it and an active substance it breaks down into stay in the body. The label says changes in dose are not fully reflected in the blood for several weeks. That also means interactions can still matter for a while after the last dose, which is why the label sets a 5-week waiting period for some medicines.

What taking fluoxetine can be like

MedlinePlus says it may take 4 to 5 weeks or longer to feel the full benefit, and that people should keep taking it even when they feel well. The label asks for close watching on mood and behavior, especially early on and at dose changes.

Some people notice anxiety, nervousness or trouble sleeping, which the label describes in its own warning. Decreased appetite and weight loss can happen, and the label flags this especially for people who are underweight. It also advises caution with driving or machinery until you know how the medicine affects you.

Do not stop fluoxetine suddenly. MedlinePlus lists withdrawal symptoms such as mood changes, irritability, agitation, dizziness, numbness or tingling, anxiety, sweating, confusion, headache and trouble sleeping. Talk with your prescriber first.

Side effects and warnings for fluoxetine

Boxed warning: antidepressants increased the risk of suicidal thoughts and behaviors in children, teens and young adults in short-term studies. These studies did not show an increase in adults over 24, and showed a reduction at 65 and older. Everyone who takes fluoxetine should be watched closely for worsening or new suicidal thoughts, and families and caregivers are asked to help. If you are in crisis, call or text 988, or call 911. Locascio Wellness does not provide emergency services. See our crisis resources too.

Common side effects on the label include unusual dreams, anxiety, weakness, diarrhea, dry mouth, indigestion, flu-like symptoms, decreased appetite, trouble sleeping, nausea, nervousness, rash, sore throat, sleepiness, sweating, tremor, yawning and sexual problems.

Dangers and combinations named on the label:

• MAOIs: contraindicated with fluoxetine, within 5 weeks after fluoxetine ends, and within 14 days before it begins. This includes linezolid and intravenous methylene blue.
• Pimozide and thioridazine: contraindicated, because of heart rhythm risk. Thioridazine also needs a 5-week gap after fluoxetine.
• Serotonin syndrome: a potentially life-threatening reaction, especially with other serotonin-affecting medicines.
• Rash and allergic reactions: the label says these have occurred, some with fever or other body-wide signs, so call your prescriber if you notice a rash or hives.
• Bleeding risk with NSAIDs, aspirin or warfarin, mania or hypomania, seizures, angle-closure glaucoma, low sodium and QT prolongation, a heart rhythm change.

Can fluoxetine be managed online in Pennsylvania and New York

Fluoxetine is not listed as a controlled substance on its FDA label. A licensed psychiatrist on our team, a Doctor of Osteopathic Medicine, treats anxiety, depression and trauma by secure video for people physically located in Pennsylvania or New York during each visit.

Whether it is an option for you is a decision for you and your prescriber. Ask us whether our psychiatrist can help, using our contact form. Fees, insurance and the ages he sees are also questions to ask us. Our therapists do not prescribe. They see clients in Pennsylvania, West Virginia, Arizona, Colorado and Florida, not New York, so a reader in New York can get psychiatry here but not therapy here.