Fluoxetine
Also known as: Prozac
Fluoxetine is an SSRI antidepressant, available only on prescription, that the NHS says is used for depression, obsessive compulsive disorder (OCD) and bulimia. US prescribing information says active drug stays in the body for weeks after dosing stops, and the NHS says anyone with thoughts of harming themselves while taking an SSRI should contact the GP or go to hospital straight away.
- Generic name
- Fluoxetine
- Active ingredient
- Fluoxetine (variants: fluoxetine hydrochloride)
- Product type
- Small-molecule medicine
- Drug class
- SSRIs
- Brand names
- UK Prozac · US Prozac, Sarafem
- Routes
- Oral
- Dosage forms
- Capsule, Tablet, Solution
- Also known as
- Prozac
- Onset and duration
- The NHS advises giving fluoxetine at least 6 weeks to work.
- Monitoring
- People with diabetes may need to check their blood sugar more regularly, according to a Sheffield Children's NHS Foundation Trust leaflet. The NHS says that if someone has felt better for 6 months or more, the doctor may suggest coming off fluoxetine. MedlinePlus says caregivers of teenagers should watch for suicidal thoughts or behaviours, and for worsening nervousness, irritability, moodiness or sleeplessness, and get medical help right away.
Availability by country
| Country | Status | Note | Source |
|---|---|---|---|
| UK | Prescription only | UK |
Legal status differs between countries and can change; each row cites the document it was taken from and applies only to the country named.
What it is used for
- Depression in adults, and in some children (NHS pages give a starting age of 8, with one page saying 5 or older)
- Obsessive compulsive disorder (OCD)
- Bulimia
- Sometimes menopause symptoms, according to the NHS
- Premenstrual dysphoric disorder and panic attacks, which US information from MedlinePlus also names
How it works in the body
Fluoxetine is a selective serotonin reuptake inhibitor (SSRI), a type of antidepressant. These medicines are thought to work by increasing the level of serotonin in the brain. US prescribing information says fluoxetine and its active breakdown product, norfluoxetine, have long half-lives, so active drug stays in the body for weeks after dosing stops.
Common side effects
- The NHS lists headaches, feeling or being sick, diarrhoea or constipation, and changes in weight as common side effects of fluoxetine.
- Sexual problems such as a lower sex drive, sleep problems, dizziness or drowsiness, and blurred vision are also listed by the NHS as common.
- The NHS says some side effects ease after a couple of weeks as the body gets used to the medicine, while some can last longer.
- The NHS advises against driving, cycling or using machinery while dizzy, drowsy or having blurred vision.
Serious: seek help
- Serotonin syndrome is a serious side effect that causes a fast heartbeat, sweating, shaking, twitching muscles and confusion; the NHS says to call NHS 111 if serious side effects are suspected.
- The NHS says to call 999 or go to A&E for chest pain or pressure, shortness of breath, severe dizziness or fainting, or a fit.
- Unexplained bruising or bleeding from the gums should prompt a call to a doctor or NHS 111 straight away, according to the NHS.
- A serious allergic reaction, such as a swollen throat or tongue or difficulty breathing, needs a call to 999, the NHS says.
- The NHS says thoughts of harming oneself or ending one's life are rare with SSRIs but can occur when treatment starts, and that people aged 24 or under may be at particular risk.
- If such thoughts occur at any time, the NHS says to contact the GP or go to hospital straight away, and to call 999 or go to A&E if in immediate danger.
- Free help is also available from Samaritans on 116 123, at any time, and from NHS 111 (mental health option).
Cautions and interactions
- Most adults can take fluoxetine, but the NHS says it is not suitable for everyone.
- The NHS advises checking first with a heart problem, epilepsy, electroconvulsive treatment, glaucoma, diabetes or a past episode of mania.
- A Sheffield Children's NHS Foundation Trust leaflet on fluoxetine says it can change blood sugar levels, so people with diabetes may need to check their blood sugar more often.
- The NHS fluoxetine page advises against drinking alcohol because it can raise the risk of side effects such as drowsiness, while another NHS page says alcohol can be drunk but may cause sleepiness and may be best avoided for the first few days.
- The NHS lists MAOI antidepressants such as moclobemide and selegiline, anticoagulants such as warfarin and apixaban, and NSAIDs such as aspirin and ibuprofen among medicines that may not mix well with fluoxetine.
- The NHS advises against taking St John's wort with fluoxetine, because it raises the risk of side effects.
- The NHS says there is not enough information on other herbal remedies and supplements taken with fluoxetine.
- US prescribing information says several weeks should pass after stopping fluoxetine before an MAOI is started, because fluoxetine stays in the body.
- The NHS says fluoxetine can be used in pregnancy if needed, and the doctor discusses the risks and benefits.
- The NHS says fluoxetine in pregnancy can sometimes cause short-term withdrawal symptoms in the newborn and, rarely, breathing problems.
- The NHS says fluoxetine can be taken while breastfeeding if the doctor or health visitor says the baby is healthy.
- The NHS advises against stopping suddenly.
Interactions
Check interactions
Taking Fluoxetine with other medicines? Add them to the checker to see what the official sources say about each pair: the mechanism, general management and monitoring, never a bare "safe".
Interactions documented in the official sources cited on each card. The list covers the medicines represented on this site and is not exhaustive; how the interaction data is compiled.
No pair records for this medicine are in the sources currently represented by Anatomy Nexus. Absence from this list does not mean no interaction exists.
Same-class and related medicines
Same class: SSRIs
Medicines that share the class of Fluoxetine. They are separate medicines with their own licences, doses and interactions, not alternative names for Fluoxetine.
Related medicines
Medicines often discussed alongside Fluoxetine: used together, compared with it, or acting on the same problem by a different route.
Key facts
| Fact | Detail |
|---|---|
| Type | SSRI antidepressant |
| Used for | Depression, OCD and bulimia, according to the NHS |
| Time to work | The NHS advises at least 6 weeks |
| Stays in the body | Active drug stays in the body for weeks after the last dose, according to US prescribing information |
| Crisis help | 999 if in immediate danger; NHS 111 (mental health option); Samaritans 116 123 (free, any time) |
What is fluoxetine used for?
Fluoxetine is an antidepressant medicine, and the NHS lists depression, obsessive compulsive disorder (OCD) and bulimia as the conditions it treats. The NHS says it can sometimes be used for menopause symptoms. MedlinePlus, a US source, names depression, OCD, some eating disorders and panic attacks, and says it relieves the symptoms of premenstrual dysphoric disorder.
The NHS depression guidance says fluoxetine is the only SSRI that can be prescribed for under-18s and, even then, only when a specialist has given the go-ahead. One NHS page says children aged 8 and older can take it for depression, while another says it is sometimes used for depression in children aged 5 or older. MedlinePlus says fluoxetine is approved to treat depression in teenagers and in children aged 8 and older. A Staffordshire and Stoke-on-Trent formulary document notes that prescribing under 8 years old is off label.
How does fluoxetine work, and why does it stay in the body?
Fluoxetine is a selective serotonin reuptake inhibitor, or SSRI, which is a type of antidepressant. SSRIs are thought to work by increasing the level of serotonin in the brain. The NHS advises giving fluoxetine at least 6 weeks to work.
Half-life is the time it takes for the amount of a medicine in the body to fall by half. US prescribing information says fluoxetine and its active breakdown product, norfluoxetine, have long half-lives. This means active drug stays in the body for weeks after dosing stops. The same labelling says several weeks should pass between stopping fluoxetine and starting an MAOI (monoamine oxidase inhibitor, a rarely used type of antidepressant) for this reason.
What are the serious side effects of fluoxetine?
The NHS describes serious side effects of fluoxetine as uncommon. Serotonin syndrome is a serious side effect that causes a fast heartbeat, sweating, shaking, twitching muscles and confusion; the NHS says to call NHS 111 if serious side effects are suspected. The NHS says to call 999 or go to A&E for chest pain or pressure, shortness of breath, severe dizziness or fainting, or a fit. Unexplained bruising or bleeding from the gums should prompt a call to a doctor or NHS 111 straight away, according to the NHS. A serious allergic reaction, such as a swollen throat or tongue or difficulty breathing, needs a call to 999, the NHS says. Signs of low sodium levels, such as headaches, trouble concentrating, memory problems or confusion, are another reason the NHS gives for calling 999 or going to A&E. The NHS says to contact NHS 111 for advice straight away after taking more than the prescribed amount of fluoxetine.
Thoughts of self-harm and where to get help
The NHS says thoughts of harming oneself or ending one's life are rare with SSRIs but can occur when treatment starts, and that people aged 24 or under may be at particular risk. If such thoughts occur at any time, the NHS says to contact the GP or go to hospital straight away, and to call 999 or go to A&E if in immediate danger. MedlinePlus says caregivers of teenagers should watch for suicidal thoughts or behaviours, and for worsening nervousness, irritability, moodiness or sleeplessness, and get medical help right away.
Free help is also available from Samaritans on 116 123, at any time, and from NHS 111 (mental health option). Samaritans says its helpline can be called free from any phone. The NHS also lists an emergency GP appointment, or the mental health crisis team for people who have one, as places to turn.
Who needs extra care, and coming off fluoxetine
Most adults can take fluoxetine, but the NHS says it is not suitable for everyone. The NHS advises checking first with a heart problem, epilepsy, electroconvulsive treatment, glaucoma, diabetes or a past episode of mania. A Sheffield Children's NHS Foundation Trust leaflet on fluoxetine says it can change blood sugar levels, so people with diabetes may need to check their blood sugar more often.
The NHS says fluoxetine can be used in pregnancy if needed, and the doctor discusses the risks and benefits. The NHS says fluoxetine in pregnancy can sometimes cause short-term withdrawal symptoms in the newborn and, rarely, breathing problems. The NHS says fluoxetine can be taken while breastfeeding if the doctor or health visitor says the baby is healthy.
The NHS says a course of SSRIs usually continues for at least 6 months after a person feels better, to prevent the condition coming back. The NHS says that if someone has felt better for 6 months or more, the doctor may suggest coming off fluoxetine. The NHS advises against stopping suddenly. After long-term use, a gradual reduction is usually recommended.
Alcohol and other medicines
The NHS fluoxetine page advises against drinking alcohol because it can raise the risk of side effects such as drowsiness, while another NHS page says alcohol can be drunk but may cause sleepiness and may be best avoided for the first few days.
The NHS lists MAOI antidepressants such as moclobemide and selegiline, anticoagulants such as warfarin and apixaban, and NSAIDs such as aspirin and ibuprofen among medicines that may not mix well with fluoxetine. The NHS advises against taking St John's wort with fluoxetine, because it raises the risk of side effects. The NHS says there is not enough information on other herbal remedies and supplements taken with fluoxetine. US prescribing information says several weeks should pass after stopping fluoxetine before an MAOI is started, because fluoxetine stays in the body.
Frequently asked questions
How long does fluoxetine take to work?
The NHS advises giving fluoxetine at least 6 weeks to work. The NHS advises against stopping suddenly.
Can fluoxetine be taken in pregnancy or while breastfeeding?
The NHS says fluoxetine can be used in pregnancy if needed, and the doctor discusses the risks and benefits. The NHS says fluoxetine in pregnancy can sometimes cause short-term withdrawal symptoms in the newborn and, rarely, breathing problems. The NHS says fluoxetine can be taken while breastfeeding if the doctor or health visitor says the baby is healthy.
Can children take fluoxetine?
The NHS depression guidance says fluoxetine is the only SSRI that can be prescribed for under-18s and, even then, only when a specialist has given the go-ahead. One NHS page says children aged 8 and older can take it for depression, while another says it is sometimes used for depression in children aged 5 or older. MedlinePlus says fluoxetine is approved to treat depression in teenagers and in children aged 8 and older. A Staffordshire and Stoke-on-Trent formulary document notes that prescribing under 8 years old is off label.
What if someone taking fluoxetine has thoughts of harming themselves?
If such thoughts occur at any time, the NHS says to contact the GP or go to hospital straight away, and to call 999 or go to A&E if in immediate danger. Free help is also available from Samaritans on 116 123, at any time, and from NHS 111 (mental health option).
Can alcohol be drunk with fluoxetine?
The NHS fluoxetine page advises against drinking alcohol because it can raise the risk of side effects such as drowsiness, while another NHS page says alcohol can be drunk but may cause sleepiness and may be best avoided for the first few days. MedlinePlus suggests talking to a doctor about alcohol use during treatment.
Connected pages in detail
What each linked page on Anatomy Nexus covers, in a line, for Fluoxetine.
Symptoms
- Dizziness An umbrella word for several sensations: vertigo (the room spins, an inner-ear or brain problem), light-headedness (about to faint.
Medical tests
- Blood glucose The concentration of glucose in blood, measured from a vein or a fingerprick.
Medications
- Sertraline and SSRIs A selective serotonin reuptake inhibitor (SSRI) antidepressant used for depression, anxiety disorders, panic and obsessive-compulsive disorder.
- Citalopram A selective serotonin reuptake inhibitor antidepressant used for depression and panic disorder, taken once daily.
- Warfarin The long-established oral anticoagulant that blocks vitamin K-dependent clotting factors.
- Aspirin A low-dose antiplatelet that stops platelets clumping into clots, used long term after heart attacks and strokes.
- Ibuprofen A non-steroidal anti-inflammatory (NSAID) that eases pain, inflammation and fever by blocking prostaglandin production.
- Mirtazapine Mirtazapine is an antidepressant, prescribed mainly for depression and sometimes for obsessive compulsive disorder (OCD) and anxiety.
- Venlafaxine Venlafaxine is an antidepressant called a serotonin and noradrenaline reuptake inhibitor (SNRI), used for depression.
Drug classes
- SSRIs The most widely used antidepressants (sertraline, citalopram, escitalopram, fluoxetine, paroxetine), also first-line for anxiety disorders, panic.