Fluoxetine (Prozac) — NZ Medication Guide | KiwiMeds
✅ Reviewed by a Registered Pharmacist NZ | Last updated: May 2026 | This information is for educational purposes only and does not replace advice from your doctor or pharmacist.
What is Fluoxetine (Prozac)?
Fluoxetine (brand name Prozac) is a selective serotonin reuptake inhibitor (SSRI) — one of the most widely prescribed antidepressants in New Zealand. It was the first SSRI to be developed and has been available since the 1980s.
What is it used for?
Fluoxetine is used to treat depression, anxiety disorders (including panic disorder, OCD, and social anxiety), bulimia nervosa, and premenstrual dysphoric disorder (PMDD). It is also used in children and adolescents for depression and OCD. Fully funded by Pharmac.
How does it work?
Fluoxetine works by blocking the reuptake of serotonin in the brain — increasing the amount of serotonin available in the synapses between nerve cells. Serotonin is a neurotransmitter involved in mood regulation, sleep, and anxiety. It takes several weeks to build up to therapeutic levels.
How to take it
Fluoxetine is usually taken once daily in the morning (as it can be activating and may interfere with sleep if taken at night). It can be taken with or without food. The full antidepressant effect takes 4–8 weeks. Do not stop without talking to your doctor — gradual reduction is recommended.
Common side effects
Common side effects include nausea (often improves after 1–2 weeks), headache, insomnia or vivid dreams, sweating, dry mouth, diarrhoea, decreased sexual desire, and difficulty reaching orgasm. Fluoxetine is generally better tolerated than older antidepressants.
Serious side effects
Important warning: SSRIs can increase suicidal thoughts in some young people (under 25) at the beginning of treatment — close monitoring is essential. Serotonin syndrome (agitation, confusion, rapid heartbeat, high temperature) can occur if combined with other serotonergic drugs — seek emergency care. Hyponatraemia (low sodium) is rare but can occur, especially in older people.
Drug interactions
Serotonin syndrome risk with tramadol, triptans (sumatriptan), St John’s Wort, MAOIs (never combine with MAOIs — serious risk). Fluoxetine inhibits CYP2D6 enzyme, affecting metabolism of many other drugs including some antipsychotics, tricyclic antidepressants, and codeine. Caution with NSAIDs and aspirin — increased bleeding risk.
Things to avoid
Avoid St John’s Wort — serious interaction risk. Avoid MAOIs. Caution with alcohol — can worsen depression and increase sedation. Avoid suddenly stopping — taper gradually to avoid discontinuation syndrome.
NZ-specific information
Fluoxetine is funded by Pharmac. Unlike other SSRIs, fluoxetine has a very long half-life (1–6 days) which means discontinuation syndrome is less severe, but drug interactions persist for weeks after stopping.
Frequently asked questions
How long should I take fluoxetine? For a first episode of depression, typically 6–12 months after remission. For recurrent depression, longer-term treatment may be recommended. Will fluoxetine change my personality? Antidepressants should not change your personality — they should help you feel more like yourself by lifting depression.
💬 Always talk to your pharmacist or doctor for advice specific to you.
Related medications
Related: Sertraline, Escitalopram. Condition: Depression, Anxiety.
References & Further Information
The following New Zealand and international resources were used to inform this page: