FLUOXETINE oral

Last updated: March 2024

Therapeutic action

• Antidepressant, selective serotonin re-uptake inhibitor (SSRI)

Indications

• Major depression
• Generalised anxiety
• Severe post-traumatic stress disorder

Forms and strengths

• 20 mg capsule

Dosage

Major depression

• Adult: 20 mg on alternate days for one week, then 20 mg once daily. In case of insufficient response after 3 weeks, increase up to 40 mg daily max.

Generalised anxiety, severe post-traumatic stress disorder

• Adult: 20 mg once daily

Duration

• Major depression: at least 9 months. Discontinue treatment gradually (e.g. half dose once daily for 2 weeks then on alternate days for 2 weeks). If signs of relapse or withdrawal occur, increase the dose then decrease it more gradually.
• Generalised anxiety, severe post-traumatic stress disorder: 2 to 3 months after symptoms resolve. Discontinue treatment gradually (over at least 2 weeks). 

Contra-indications, adverse effects, precautions

• Administer with caution and monitor use in patients with epilepsy, diabetes, hepatic impairment (reduce dose or frequency of administration) or severe renal impairment; history of gastrointestinal bleeding, bipolar disorders, suicidal ideation (in young adults) or closed-angle glaucoma.
• May cause:
  • gastrointestinal disturbances, drowsiness (caution when driving or operating machinery); fatigue, headache, dizziness, seizures, sexual dysfunction, blurred vision, hyponatraemia especially in older patients;
  • mental disorders: anxiety, insomnia, agitation, aggressive behaviour, suicidal ideation in young adults;
  • withdrawal symptoms very frequent if discontinued abruptly: dizziness, paraesthesia, nightmares, anxiety, tremors and headaches.
• Avoid combination with:
  • aspirin, NSAIDs and warfarin (risk of bleeding);
  • serotonergic drugs: other SSRI, tricyclic antidepressants, ondansetron, tramadol, etc. (risk of serotonin syndrome).
• Monitor combination with: carbamazepine, phenytoin, risperidone (increased plasma concentrations), drugs which lower the seizure threshold (antipsychotics, mefloquine, etc.). 
• Avoid alcohol during treatment (increased risk of adverse effects).
• Pregnancy: re-evaluate whether the treatment is still necessary; if it is continued, maintain fluoxetine at effective dose or consider switching to another SSRI if the woman plans to breast-feed. Observe the neonate (risk of agitation, tremors, hypotony, respiratory difficulties, sleeping disorders, etc.) if the mother was under treatment in the 3^rd trimester. If treatment starts during pregnancy, preferably use sertraline.
• Breast-feeding: avoid; consider switching to sertraline or if not available, paroxetine.

Remarks

• Do not open the capsules.
• It is necessary to wait at least 2 to 3 weeks before assessing the antidepressant effect. This must be explained to the patient.

Storage