Fluoxetine: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
Fluoxetine: clinical details
Prescribing considerations
- Assess suicide and self-harm risk and monitor for clinical worsening.
- In children and adolescents, restrict use to the licensed depressive indication under specialist supervision with concurrent psychological therapy.
- Use caution with seizure disorders, previous mania or hypomania, diabetes, hepatic impairment, bleeding risk, glaucoma and cardiac or QT-prolongation risk.
- Fluoxetine and norfluoxetine persist for weeks, materially affecting switching and interaction planning.
- Assess pregnancy and breastfeeding treatment individually.
Contraindications and cautions
- Hypersensitivity to fluoxetine or a product excipient.
- Concomitant use with an irreversible non-selective MAOI.
- Concomitant use with metoprolol for heart failure.
Monitoring
- Mood, suicidality, agitation, akathisia and mania or hypomania.
- Symptoms of serotonin syndrome with serotonergic medicines.
- Height, weight and pubertal development during paediatric treatment.
- Blood glucose in people with diabetes.
- Serum sodium when symptoms or risk factors for hyponatraemia are present.
- Bleeding and anticoagulant effect where relevant.
- ECG when cardiac disease, electrolyte disturbance, congenital long-QT syndrome or interacting medicines increase arrhythmia risk.
- Seizure frequency in controlled epilepsy.
Clinical pharmacology
Fluoxetine is an SSRI and strong CYP2D6 inhibitor. It is extensively metabolised to substances including active norfluoxetine. Both have long elimination half-lives, so exposure and interactions can persist for several weeks after stopping.
Formulation and product differences
- Selected products include hard capsules, conventional tablets, oral solution and scored dispersible tablets.
- The dispersible tablet can be swallowed or dispersed in water and contains sorbitol and sulfur dioxide.
- The oral solution contains sorbitol and benzoic acid and should be measured with an appropriate device.
- Capsule and oral-solution formulations are described as bioequivalent in the capsule product information.
Fluoxetine preparations and strengths
Capsule
Route: Oral
Strengths: 10 mg, 20 mg, 30 mg, 40 mg, 60 mg
Fluoxetine interactions
Check all prescribed, pharmacy and herbal products with a pharmacist or prescriber because interactions can persist after fluoxetine is stopped.
Irreversible non-selective monoamine oxidase inhibitors (MAOIs)
Contraindicated because the combination can cause severe or fatal serotonin syndrome.
Metoprolol used for heart failure
Contraindicated because fluoxetine can increase metoprolol exposure and cause excessive slowing of the heart.
Tamoxifen
Fluoxetine may reduce formation of tamoxifen's active metabolite and should be avoided where possible.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.