Fluoxetine Dosage

This dosage information may not include all the information needed to use Fluoxetine safely and effectively. See additional information for Fluoxetine.

The information at Drugs.com is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Premenstrual Dysphoric Disorder

Initial dose: 20 mg orally once daily.
Maintenance dose: 20 mg/day continuously or, alternatively, 20 mg/day during the luteal phase of the menstrual system (the 14 days prior to the anticipated start of menses). The 20 mg/day dosage has been shown to be effective for up to six months of treatment. A 60 mg/day dosage has also been studied, but has not been shown to be significantly more effective than 20 mg/day.
Maximum dose: 80 mg/day.

Usual Adult Dose for Depression

Immediate-release capsules or tablets:
Initial dose: 20 mg orally once a day in the morning.
Maintenance dose: 20 to 80 mg/day in 1 to 2 divided doses.

Extended-release capsules: Patients taking 20 mg daily may be converted to 90 mg orally once a week. The first weekly dose should be given 7 days after the last daily dose.

Usual Adult Dose for Obsessive Compulsive Disorder

Initial dose: 20 mg orally once a day in the morning.
Maintenance dose: 20 to 60 mg/day in 1 to 2 divided doses.
Maximum dose: 80 mg/day.

Usual Adult Dose for Panic Disorder

Initial dose: 20 mg orally once a day in the morning.
Maintenance dose: 20 to 60 mg/day in 1 to 2 divided doses.
Maximum dose: 80 mg/day.

Usual Adult Dose for Bulimia

Initial dose: 60 mg orally once a day in the morning. Some patients have started with lower doses. Doses greater than 60 mg/day have not been systematically studied.

Usual Pediatric Dose for Depression

Major depression:

7 years or younger:
Safety and efficacy have not been established.

8 years to less than 18 years:
Initial dose: 10 to 20 mg orally once daily. After 1 week at 10 mg/day, the dose should be increased to 20 mg/day.

Lower weight children:
Due to higher plasma levels in lower weight children, the starting and target dose in this group should generally be 10 mg/day. A dose increase to 20 mg/day may be considered after several weeks if clinical improvement is insufficient.

Usual Pediatric Dose for Obsessive Compulsive Disorder

6 years or younger:
Safety and efficacy have not been established.

7 years to less than 18 years:
Initial dose: 10 mg orally once daily.

Adolescents and higher weight children:
After 2 weeks at 10 mg/day, the dose should be increased to 20 mg/day. Additional dose increases may be considered after several more weeks if clinical improvement is insufficient. A dose range of 20 to 60 mg/day is recommended.

Lower weight children:
Additional dose increases may be considered after several weeks if clinical improvement is insufficient. A dose range of 20 to 30 mg/day is recommended. There is minimal experience with doses greater than 20 mg/day and none with doses greater than 60 mg/day.

Renal Dose Adjustments

Dosage adjustments for renal dysfunction are not routinely necessary.

Liver Dose Adjustments

Adults:
Initial dose: 20 mg orally every other day or 10 mg once a day in the morning.
Maintenance dose: May increase to 20 mg/day after 2 to 3 weeks. Additional increases may be made in 10 to 20 mg/day increments every 2 to 3 weeks.

Children:
Lower or less frequent doses are recommended; however, there is not enough information to make any specific recommendations.

Dose Adjustments

A dose increase may be considered after several weeks if no clinical improvement is observed. Doses above 20 mg/day may be administered once a day (morning) or twice a day (i.e., morning and noon).

A lower or less frequent dosage should be used in patients with renal and/or hepatic impairment.

Precautions

Children, adolescents, and young adults (18 to 24 years of age) with major depressive disorder and other psychiatric disorders may be at an increased risk of suicidal thinking and suicidality with antidepressant use, particularly during the first few months of treatment. Medical evidence has not shown this increased risk to exist in adults older than 24 years of age, but adults 65 years of age and older taking antidepressants appear to have a decreased risk of suicidality. The results of a meta-analysis indicate an overall favorable risk-to-benefit profile for the use of antidepressants (i.e., selective serotonin and/or norepinephrine reuptake inhibitors) in the treatment of pediatric patients (less than 19 years old) with major depressive disorders (MDD), obsessive-compulsive disorder (OCD), or non- OCD anxiety disorders. Although this study also reports an overall increased risk of suicidal ideation/suicide attempt associated with the use of antidepressants in pediatric patients, the risk may be less than originally estimated. Additional prospective studies are warranted in order to confirm these findings.

In controlled clinical trials, suicide- related events have been reported in 1.75% of fluoxetine- treated children and adolescents versus 0.55% of placebo- treated patients, and suicide attempts have been reported in 1.3% versus 0.5% of these patients, respectively. The FDA estimates that antidepressants may increase suicidal thoughts and actions in approximately 1 out of 50 pediatric patients (18 years or younger).

Worsening of depression and/or increased suicidal thinking or behavior may always be a possibility in patients treated with antidepressant medications, particularly those being treated for depression. Anxiety, agitation, panic attacks, insomnia, irritability, hostility, impulsivity, akathisia (severe restlessness), hypomania, and mania have been reported in patients being treated with antidepressants for major depressive disorder as well as for other indications, both psychiatric and nonpsychiatric. It is unknown if these symptoms are a precursor to either worsening of depression or the emergence of suicidal impulses; however, there is concern that patients who experience one or more of these symptoms may be at increased risk for worsening depression or suicidality. Although the FDA has not concluded that antidepressant drugs cause worsening depression or suicidality, health care providers should be aware that worsening of symptoms could be due to the underlying disease or might be a result of drug therapy.

Health care providers should carefully monitor patients receiving antidepressants for possible and/or persistent worsening of depression or emergent suicidality, especially at the beginning of therapy or when the dose either increases or decreases. If symptoms are severe, abrupt in onset, or were not part of the patient's presenting symptoms, the health care provider will need to determine what intervention, including discontinuing or modifying the current drug therapy, is indicated. Prescriptions should be written for small quantities of drug to reduce the risk of an attempt to overdose. Health care providers should instruct patients, their families and their caregivers to be alert for the emergence of agitation, irritability, and the other symptoms described above, as well as the emergence of suicidality and worsening depression, and to report such symptoms immediately to their health care provider.

Because antidepressants are believed to have the potential for inducing manic episodes in patients with bipolar disorder, there is a concern about using antidepressants alone in this population. Therefore, patients should be adequately screened to determine if they are at risk for bipolar disorder before initiating antidepressant treatment so that they can be appropriately monitored during treatment. Such screening should include a detailed psychiatric history, including a family history of suicide, bipolar disorder, and depression.

Fluoxetine is known to inhibit CYP450 2D6 activity. Fluoxetine should be used with caution when concomitant administration with other drugs that are metabolized by CYP450 2D6 is unavoidable, particularly drugs with a narrow therapeutic index. Plasma levels may need to be monitored and dosing adjustments may be required when fluoxetine is used concurrently or has been recently discontinued (within preceding 5 weeks). Use of thioridazine is considered contraindicated with fluoxetine or within a minimum of 5 weeks after fluoxetine has been discontinued.

The concomitant use of fluoxetine with monoamine oxidase inhibitors to treat depression is contraindicated. At least 14 days should elapse between discontinuation of an MAOI and initiation of therapy with fluoxetine. At least 5 weeks, perhaps longer, should be allowed after stopping fluoxetine before starting an MAOI.

Dialysis

Fluoxetine is not removed by hemodialysis.

Other Comments

The full therapeutic effects of fluoxetine may not be observed until 4 weeks or more after initiation of therapy.

Doses greater than 20 mg/day may be divided into morning and noon doses.

Because fluoxetine can cause insomnia, nighttime dosing should be limited to those patients experiencing sedation.

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