10 mg Fluoxetine for Generalized Anxiety Disorder
10 mg fluoxetine is an appropriate and recommended starting dose for GAD, particularly as a "test dose" to minimize initial anxiety or agitation that commonly occurs when initiating SSRI therapy. 1, 2
Rationale for Low Starting Dose
SSRIs can paradoxically cause initial anxiety or agitation when first started, making it advisable to begin with a subtherapeutic dose before titrating to therapeutic levels. 1, 2
The American Academy of Child and Adolescent Psychiatry specifically recommends starting with a subtherapeutic "test" dose for anxiety disorders to assess tolerability before advancing to therapeutic dosing. 1, 2
This conservative approach is particularly important in GAD patients who may be hypersensitive to activation side effects. 1
Titration Strategy After 10 mg Start
Due to fluoxetine's exceptionally long half-life (4-6 days for fluoxetine, 4-16 days for norfluoxetine), dose increases should occur at 3-4 week intervals rather than the 1-2 week intervals used for shorter-acting SSRIs like sertraline. 1, 2
Side effects may not fully manifest for several weeks due to the prolonged half-life, so patience is required when assessing tolerability at each dose level. 2
Titrate upward in the smallest available increments (typically 10 mg steps) until the benefit-to-harm ratio is optimized and remission is achieved. 1
Evidence for SSRI Efficacy in GAD
Antidepressants including SSRIs are superior to placebo for treating GAD, with a number needed to treat (NNT) of 5.15. 3
Paroxetine at 20-50 mg/day demonstrated significant efficacy in GAD with response rates of 62-68% versus 46% for placebo, and remission rates of 30-36% versus 20% for placebo. 4, 5
While the specific evidence cited focuses on paroxetine, SSRIs as a class are effective for GAD, and fluoxetine is an established option. 6, 3
Important Caveats
It is unclear whether higher SSRI doses produce greater response magnitude in anxiety disorders, though higher doses can increase adverse effects. 1
The long half-life of fluoxetine provides an advantage for discontinuation—plasma concentrations decrease gradually, minimizing discontinuation syndrome risk compared to shorter-acting SSRIs like paroxetine. 2
In CYP2D6 poor metabolizers, fluoxetine exposure can be 3.9-11.5 fold higher, increasing risk of QT prolongation and adverse effects—consider genetic testing or alternative agents in patients with known poor metabolizer status. 2
GAD is a chronic condition requiring long-term treatment; remission may take several months, and stopping medication prematurely increases relapse risk within the first year. 6