Maximum Recommended Dose of Fluoxetine (Prozac)

The maximum recommended dose of fluoxetine (Prozac) is 80 mg per day for adults, as indicated in the FDA drug label. 1

Standard Dosing by Indication

Initial dose: 20 mg once daily in the morning 1
Dose increases may be considered after several weeks if insufficient clinical improvement is observed 1
Doses above 20 mg/day may be administered once daily (morning) or twice daily (morning and noon) 1
Maximum dose: 80 mg/day 1
For maintenance treatment, efficacy has been demonstrated at 20 mg/day for up to 38 weeks 1

Initial dose: 20 mg/day administered in the morning 1
Recommended dose range: 20 to 60 mg/day 1
Maximum dose: 80 mg/day (doses up to 80 mg/day have been well tolerated in open studies) 1
Full therapeutic effect may be delayed until 5 weeks of treatment or longer 1

Recommended dose: 60 mg/day, administered in the morning 1
For some patients, titration to this target dose over several days may be advisable 1
Doses above 60 mg/day have not been systematically studied in bulimia 1

For major depression in children and adolescents:
- Lower weight children: 10-20 mg/day 1
- Higher weight children and adolescents: Initial dose of 10 mg/day, increased to 20 mg/day after 1 week 1
For OCD in pediatric patients:
- Adolescents and higher weight children: Start with 10 mg/day, increase to 20 mg/day after 2 weeks, dose range of 20-60 mg/day 1
- Lower weight children: Start with 10 mg/day, dose range of 20-30 mg/day 1

Lower or less frequent dosage should be used 1
Dose adjustments should be made to maintain the patient on the lowest effective dosage 1

Fluoxetine has a long elimination half-life of 1-3 days after a single dose and approximately 4 days after long-term administration 2
Its active metabolite, norfluoxetine, has an even longer half-life of approximately 7 days 2
This long half-life allows for once-weekly dosing in some maintenance situations 1, 3

Some patients may respond to doses lower than the standard 20 mg/day 4, 5
In a study of patients with major depression and panic disorder, 28% of patients were unable to tolerate the standard 20 mg/day dose, with half of these patients benefiting from lower doses 4
There may be a "therapeutic window" effect with fluoxetine, where both underdosing and overdosing can result in suboptimal response 5
Activation side effects (nervousness, anxiety, agitation, insomnia) appear relatively stable between 5-40 mg/day but increase at 60 mg/day 6
Sedation side effects increase linearly up to 40 mg/day 6

Regular assessment of clinical response and side effects is essential when adjusting doses 1
Patients should be periodically reassessed to determine the need for continued treatment, especially in maintenance therapy 1