Drug action
Drug action For all selective serotonin re-uptake inhibitors
Selectively inhibit the re-uptake of serotonin (5-hydroxytryptamine, 5-HT).
Indications and dose
For fluoxetine
Major depression for fluoxetine
By mouth
- Adult
- Initially 20mg once daily, daily dose may be administered as a divided dose, increased if necessary up to 60mg once daily, daily dose may be administered as a divided dose; dose may be increased after 3–4 weeks of initial dose, and at appropriate intervals thereafter.
- Elderly
- Initially 20mg once daily, daily dose may be administered as a divided dose, increased if necessary up to 40mg once daily, daily dose may be administered as a divided dose; dose may be increased after 3–4 weeks of initial dose, and at appropriate intervals thereafter, usual maximum dose is 40mg per day but doses up to 60mg per day can be used.
Bulimia nervosa for fluoxetine
By mouth
- Adult
- 60mg once daily, daily dose may be administered as a divided dose.
- Elderly
- Up to 40mg once daily, daily dose may be administered as a divided dose; usual maximum dose is 40mg per day but doses up to 60mg per day can be used.
Obsessive-compulsive disorder for fluoxetine
By mouth
- Adult
- 20mg once daily, daily dose may be administered as a divided dose, increased if necessary up to 60mg once daily, daily dose may be administered as a divided dose, dose to be increased gradually, review treatment if inadequate response after 10 weeks.
- Elderly
- 20mg once daily, daily dose may be administered as a divided dose, increased if necessary up to 40mg once daily, daily dose may be administered as a divided dose, dose to be increased gradually; usual maximum dose is 40mg per day but doses up to 60mg per day can be used, review treatment if inadequate response after 10 weeks.
Menopausal symptoms, particularly hot flushes, in women with breast cancer (except those taking tamoxifen) for fluoxetine
By mouth
- Adult
- 20mg once daily.
Pharmaco*kinetics for fluoxetine
Consider the long half-life of fluoxetine when adjusting dosage (or in overdosage).
Unlicensed use
Unlicensed use For fluoxetine
Fluoxetine is used for menopausal symptoms, B but it is not licensed for this indication.
Important safety information
Important safety information For all selective serotonin re-uptake inhibitors
MHRA/CHM advice: SSRI/SNRI antidepressant medicines: small increased risk of postpartum haemorrhage when used in the month before delivery (January 2021)
SSRIs are known to increase the risk of bleeding due to their effect on platelet function. Observational data suggest that the use of SSRIs in the last month before delivery may increase the risk of postpartum haemorrhage. Healthcare professionals should continue to consider the benefits and risks of antidepressant use during pregnancy, and the risks of untreated depression in pregnancy.
Healthcare professionals should also consider this finding in the context of individual patient risk factors for bleeding or thrombotic events. Anticoagulant medication in women at high risk of thrombotic events should not be stopped but healthcare professionals should be aware of the risk identified.
Contra-indications
Contra-indications For all selective serotonin re-uptake inhibitors
Poorly controlled epilepsy; SSRIs should not be used if the patient enters a manic phase
Cautions
Cautions For all selective serotonin re-uptake inhibitors
Cardiac disease; concurrent electroconvulsive therapy; diabetes mellitus; epilepsy (discontinue if convulsions develop); history of bleeding disorders (especially gastro-intestinal bleeding); history of mania; susceptibility to angle-closure glaucoma
Cautions, further information
Elderly
Screening Tool of Older Persons' potentially inappropriate Prescriptions (STOPP) criteria to aid medication reviews (see Prescribing in the elderly for information): potentially inappropriate with current or recent significant hyponatraemia i.e. serum sodium less than 130 mmol/L (risk of exacerbating or precipitating hyponatraemia).
Interactions
View interactions for fluoxetine
Side-effects
Side-effects For all selective serotonin re-uptake inhibitors
Common or very common
Anxiety; appetite abnormal; arrhythmias; arthralgia; asthenia; concentration impaired; confusion; constipation; depersonalisation; diarrhoea; dizziness; drowsiness; dry mouth; fever; gastrointestinal discomfort; haemorrhage; headache; hyperhidrosis; malaise; memory loss; menstrual cycle irregularities; myalgia; mydriasis; nausea (dose-related); palpitations; paraesthesia; QT interval prolongation; sexual dysfunction; skin reactions; sleep disorders; taste altered; tinnitus; tremor; urinary disorders; visual impairment; vomiting; weight changes; yawning
Uncommon
Alopecia; angioedema; behaviour abnormal; hallucination; mania; movement disorders; photosensitivity reaction; postural hypotension; seizure; suicidal behaviours; syncope
Rare or very rare
Galactorrhoea; hepatitis; hyperprolactinaemia; hyponatraemia; serotonin syndrome; severe cutaneous adverse reactions (SCARs); SIADH; thrombocytopenia
Frequency not known
Withdrawal syndrome
Side-effects, further information
Symptoms of sexual dysfunction may persist after treatment has stopped.
Overdose
Symptoms of poisoning by selective serotonin re-uptake inhibitors include nausea, vomiting, agitation, tremor, nystagmus, drowsiness, and sinus tachycardia; convulsions may occur. Rarely, severe poisoning results in the serotonin syndrome, with marked neuropsychiatric effects, neuromuscular hyperactivity, and autonomic instability; hyperthermia, rhabdomyolysis, renal failure, and coagulopathies may develop.
For details on the management of poisoning, see Selective serotonin re-uptake inhibitors, under Emergency treatment of poisoning.
Side-effects For fluoxetine
Common or very common
Chills; feeling abnormal; postmenopausal haemorrhage; uterine disorder; vasodilation; vision blurred
Uncommon
Cold sweat; dysphagia; dyspnoea; hypotension; mood altered; muscle twitching; self-injurious behaviour; temperature sensation altered; thinking abnormal
Rare or very rare
Buccoglossal syndrome; leucopenia; neutropenia; oesophageal pain; pharyngitis; respiratory disorders; serum sickness; speech disorder; vasculitis
Frequency not known
Bone fracture
Pregnancy
Pregnancy For all selective serotonin re-uptake inhibitors
Specialist sources indicate SSRIs may be suitable for use in pregnancy, but the risks and benefits of use must be considered, and the lowest effective dose should be used. The available data regarding malformation risk for all SSRIs are conflicting and confounded, and a causal association between the use of SSRIs in pregnancy, and spontaneous miscarriage, preterm delivery, low birth weight, and adverse effects on infant neurodevelopment remains unconfirmed.
Published data on first trimester use of fluoxetine and paroxetine are contradictory. Some studies suggest a small increased risk of cardiovascular malformations with the use of fluoxetine, and congenital malformations (particularly cardiovascular) with the use of paroxetine, however other studies do not support an association.
There may be a small increased risk of persistent pulmonary hypertension in the newborn with the use of SSRIs beyond 20 weeks’ gestation, and use in the later stages of pregnancy may result in neonatal withdrawal syndrome—neonates should be monitored for associated central nervous system, motor, respiratory, and gastro-intestinal symptoms.
There may also be a small increased risk of postpartum haemorrhage when used in the month before delivery (see Important safety information).
Breast feeding
Breast feeding For all selective serotonin re-uptake inhibitors
Specialist sources indicate that sertraline and paroxetine are the SSRIs of choice in breast-feeding based on passage into milk, half-life, and published evidence of safety. However, all SSRIs can be used in breast-feeding with caution, and since there are risks with switching an SSRI, it may be more clinically appropriate to continue treatment with an SSRI that has been effective, or restart treatment with an SSRI that has previously been effective. With all SSRIs, infants should be monitored for drowsiness, poor feeding, adequate weight gain, gastro-intestinal disturbances, irritability, and restlessness.
Breast feeding For fluoxetine
Specialist sources indicate use with caution. Present in milk in moderate to significant amounts; very long half-life increases risk of accumulation in the infant.
Hepatic impairment
Hepatic impairment For all selective serotonin re-uptake inhibitors
In general, manufacturers advise caution (prolonged half-life).
Hepatic impairment For fluoxetine
Dose adjustments
Manufacturer advises dose reduction or increasing dose interval.
Treatment cessation
Treatment cessation For all selective serotonin re-uptake inhibitors
Gastro-intestinal disturbances, headache, anxiety, dizziness, paraesthesia, electric shock sensation in the head, neck, and spine, tinnitus, sleep disturbances, fatigue, influenza-like symptoms, and sweating are the most common features of abrupt withdrawal of an SSRI or marked reduction of the dose; palpitation and visual disturbances can occur less commonly. The dose should be tapered over at least a few weeks to avoid these effects. For some patients, it may be necessary to withdraw treatment over a longer period; consider obtaining specialist advice if symptoms persist.
Withdrawal effects may occur within 5 days of stopping treatment with antidepressant drugs; they are usually mild and self-limiting, but in some cases may be severe. The risk of withdrawal symptoms is increased if the antidepressant is stopped suddenly after regular administration for 8 weeks or more.
Directions for administration
Directions for administration For fluoxetine
Manufacturer advises dispersible tablets can be dispersed in water for administration or swallowed whole with plenty of water.
Patient and carer advice
Patient and carer advice For all selective serotonin re-uptake inhibitors
Driving and skilled tasks
May also impair performance of skilled tasks (e.g. driving, operating machinery).
Patient and carer advice For fluoxetine
Patients and carers should be counselled on the administration of dispersible tablets.
Driving and skilled tasks
Patients should be counselled about the effects on driving and skilled tasks.
Medicinal forms
There can be variation in the licensing of different medicines containing the same drug.
Forms available from special-order manufacturers include: oral suspension, oral solution.
View all medicinal forms and pricinginformation
Or jump straight to:
- Oral tablet
- Dispersible tablet
- Oral capsule
- Oral solution
- Depression
- Premature ejacul*tion
Other drugs in class
Other drugs in classSelective serotonin re-uptake inhibitors
- Citalopram
- Dapoxetine
- Escitalopram
- Fluvoxamine maleate
- Paroxetine
- Sertraline
