Fluoxetine: a cornerstone of modern psychopharmacology
Fluoxetine is one of the most significant pharmaceutical developments in the history of psychiatry, representing the first selective serotonin reuptake inhibitor approved for clinical use and ushering in a new era in the pharmacological treatment of depression and related disorders. Originally introduced to the market under the brand name Prozac, Fluoxetine rapidly became one of the most widely prescribed medications in the world, transforming the landscape of mental health treatment and challenging long-held stigmas surrounding psychiatric illness and its treatment. The impact of Fluoxetine extends far beyond its clinical efficacy, as the medication became a cultural phenomenon that symbolized a broader societal shift toward the medicalization and destigmatization of mental health conditions. Understanding Fluoxetine requires an appreciation of its pharmacological properties, its diverse clinical applications, and its place in the evolution of psychiatric therapeutics.
The serotonergic hypothesis of depression, which posits that deficient serotonin neurotransmission contributes to the pathophysiology of depressive disorders, provided the theoretical foundation for the development of Fluoxetine. While the original monoamine hypothesis has been refined and expanded over the decades, the central role of serotonin in mood regulation, anxiety, appetite, sleep, and numerous other physiological and psychological processes remains well established. Fluoxetine, by selectively inhibiting the reuptake of serotonin from the synaptic cleft, increases the availability of this neurotransmitter for postsynaptic receptor activation, thereby enhancing serotonergic neurotransmission throughout the brain. The selectivity of this mechanism distinguishes Fluoxetine from earlier antidepressants, including tricyclic compounds and monoamine oxidase inhibitors, which affect multiple neurotransmitter systems and carry greater toxicity and side effect burdens.
Molecular pharmacology and neurobiological effects
At the molecular level, Fluoxetine functions as a potent inhibitor of the serotonin transporter, a transmembrane protein located on the presynaptic terminal of serotonergic neurons that is responsible for the reuptake of serotonin from the synaptic cleft back into the presynaptic neuron. Under normal physiological conditions, serotonin released into the synapse in response to neuronal activation binds to postsynaptic serotonin receptors, transmitting the chemical signal from one neuron to the next. The serotonin transporter terminates this signal by recapturing serotonin molecules and returning them to the presynaptic terminal, where they are either repackaged into synaptic vesicles for future release or degraded by monoamine oxidase enzymes. Fluoxetine binds to the serotonin transporter with high affinity, preventing the reuptake process and allowing serotonin to remain in the synaptic cleft for an extended period.
The increased synaptic serotonin concentration that results from transporter blockade leads to enhanced activation of postsynaptic serotonin receptors, of which there are at least fourteen distinct subtypes distributed throughout the central nervous system. The specific pattern of receptor activation, determined by the regional distribution of receptor subtypes and the neural circuits in which they are embedded, mediates the therapeutic and adverse effects of Fluoxetine. The 5-HT1A receptor, highly expressed in the hippocampus, amygdala, and raphe nuclei, is thought to play a particularly important role in the antidepressant response. Activation of postsynaptic 5-HT1A receptors in limbic and cortical regions enhances neuroplasticity and promotes adaptive changes in gene expression that are believed to underlie the therapeutic effects of serotonin reuptake inhibitors. The delay between the initiation of Fluoxetine therapy and the onset of clinical improvement, typically two to four weeks, reflects time required for these neuroadaptive changes to develop.
The effects of Fluoxetine extend beyond the serotonin transporter to encompass a range of additional pharmacological actions that contribute to both its therapeutic profile and its side effects. Fluoxetine has weak inhibitory effects on the norepinephrine transporter and the dopamine transporter, though these actions are generally not clinically significant at therapeutic doses. The drug also exhibits antagonist activity at 5-HT2C receptors, which has been implicated in its effects on appetite and weight. The active metabolite of Fluoxetine, norfluoxetine, is formed through N-demethylation in the liver and possesses pharmacological activity similar to that of the parent compound, with a comparably high affinity for the serotonin transporter. The extended half-life of norfluoxetine, approximately four to sixteen days, contributes to the prolonged pharmacological effects of Fluoxetine and necessitates careful consideration when discontinuing the medication or switching to alternative antidepressants.
Clinical indications and therapeutic applications
Major depressive disorder is the primary and most studied indication for Fluoxetine therapy. The efficacy of Fluoxetine in the treatment of major depression has been shown in numerous randomized, placebo-controlled clinical trials encompassing thousands of patients across the full spectrum of depressive severity. Fluoxetine has been shown to be superior to placebo in reducing depressive symptoms as measured by standardized rating scales including the Hamilton Depression Rating Scale and the Montgomery-Asberg Depression Rating Scale, with response rates typically ranging from fifty to sixty percent compared to thirty to forty percent for placebo. The medication is effective across the adult lifespan, from young adults to the elderly, though dosing considerations and side effect profiles may vary with age. Fluoxetine is also effective in the maintenance treatment of depression, reducing the risk of relapse and recurrence when continued beyond the acute phase of treatment.
Obsessive-compulsive disorder is another well-established indication for Fluoxetine, with the medication demonstrating efficacy at doses that are often higher than those used for depression. The serotonergic system has been strongly implicated in the pathophysiology of obsessive-compulsive disorder, and the robust serotonin reuptake inhibition produced by Fluoxetine at higher doses is thought to account for its therapeutic effects in this condition. Clinical trials have demonstrated significant reductions in obsessive-compulsive symptoms, as measured by the Yale-Brown Obsessive Compulsive Scale, in patients treated with Fluoxetine compared to placebo, with treatment effects becoming apparent after four to six weeks and continuing to improve over several months of therapy. The combination of Fluoxetine with cognitive behavioral therapy, particularly exposure and response prevention, may produce greater and more durable improvements than either treatment alone.
Bulimia nervosa, an eating disorder characterized by recurrent episodes of binge eating followed by inappropriate compensatory behaviors, is A FDA-approved indication for Fluoxetine that reflects medication’s effects on appetite regulation and impulse control. Clinical trials have demonstrated that Fluoxetine, at a dose of 60 milligrams daily, reduces the frequency of binge eating and purging episodes compared to placebo, with improvements evident within the first few weeks of treatment. The mechanism by which Fluoxetine reduces binge-purge behavior is not fully understood but may involve serotonergic modulation of satiety signaling, impulse control, and mood regulation. Fluoxetine has also been investigated for the treatment of binge eating disorder and has shown promise in reducing binge eating frequency, though it is not specifically approved for this indication.
Premenstrual dysphoric disorder, a severe form of premenstrual syndrome characterized by marked mood disturbances, irritability, and physical symptoms during the luteal phase of the menstrual cycle, is another approved indication for Fluoxetine. The efficacy of Fluoxetine in this condition may be related to serotonergic modulation of the neurosteroid and hormonal changes that occur during the menstrual cycle. Fluoxetine can be administered either continuously throughout the menstrual cycle or intermittently, during the luteal phase only, with both strategies demonstrating efficacy in reducing symptoms. The onset of therapeutic effect in premenstrual dysphoric disorder is more rapid than in depression, with improvement often observed within the first menstrual cycle of treatment.
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Dosage strategies and treatment planning
The dosing of Fluoxetine is tailored to the specific indication being treated, the patient’s age and clinical characteristics, and the individual’s response and tolerability. For major depressive disorder in adults, the recommended starting dose is 20 milligrams daily, administered as a single dose in the morning to minimize the potential for insomnia, which can occur if the medication is taken later in the day. The full therapeutic effect of Fluoxetine at a given dose may not be evident for four to six weeks, and dose adjustments should be made at intervals of at least four weeks to allow adequate time for clinical response assessment. If insufficient improvement is observed at the 20-milligram dose, the dosage may be increased in 20-milligram increments, up to a maximum of 80 milligrams daily, though doses above 40 milligrams daily are rarely necessary for depression and are associated with an increased adverse effect burden.
For obsessive-compulsive disorder, higher doses of Fluoxetine are often required to achieve optimal therapeutic response. Treatment is typically initiated at 20 milligrams daily, with dose escalation to 40, 60, or 80 milligrams daily over several weeks based on clinical response and tolerability. The time required for anti-obsessional effects to become apparent may be longer than that for antidepressant effects, and patients should be counseled to allow eight to twelve weeks at an adequate dose before concluding that the medication is ineffective. The higher doses used for obsessive-compulsive disorder are generally well tolerated by most patients, though the intensity and frequency of certain side effects, including gastrointestinal symptoms and activation, may increase at higher doses.
For bulimia nervosa, the established effective dose is 60 milligrams daily, and clinical trials have not demonstrated additional benefit at lower doses. Treatment is often initiated at 20 milligrams daily, with gradual dose escalation to minimize gastrointestinal side effects. The reduction in binge-purge frequency often becomes evident within two to four weeks of achieving the target dose, though maximum improvement may require several months of continued treatment. For premenstrual dysphoric disorder, Fluoxetine can be administered either continuously at 20 milligrams daily throughout the menstrual cycle or intermittently at 20 milligrams daily during the luteal phase only, starting fourteen days before the expected onset of menses and continuing through the first few days of menstruation. The intermittent dosing strategy reduces overall medication exposure and may be preferred by patients who wish to minimize treatment during the asymptomatic follicular phase of their cycles.
Adverse effects and management strategies
The adverse effect profile of Fluoxetine reflects its primary pharmacological action as a serotonin reuptake inhibitor, with most side effects attributable to enhanced serotonergic tone in peripheral and central nervous system pathways. Gastrointestinal side effects, including nausea, diarrhea, and dyspepsia, are among the most commonly reported adverse effects and result from serotonin’s role in regulating gastrointestinal motility and secretion. These symptoms are typically most pronounced during the initial weeks of therapy and tend to diminish over time as tolerance develops. Taking Fluoxetine with food, initiating therapy at a low dose, and employing gradual dose escalation can minimize gastrointestinal side effects. In persistent cases, antiemetic or antidiarrheal medications may provide symptomatic relief while the patient adjusts to the medication.
Central nervous system effects of Fluoxetine include insomnia, agitation, anxiety, and headache, which reflect serotonin’s role as a modulator of arousal, sleep-wake cycles, and pain perception. The activating effects of Fluoxetine, which distinguish it from the more sedating antidepressants, can be beneficial for patients with depression characterized by hypersomnia, fatigue, and psychomotor retardation, but they may exacerbate symptoms in patients with prominent anxiety or agitation. Administering Fluoxetine in the morning can minimize sleep disruption, and short-term use of a benzodiazepine or sedating medication may help manage activation during the initial phase of treatment. Headaches related to Fluoxetine are generally mild and respond to over-the-counter analgesics, though persistent or severe headaches warrant further evaluation.
Sexual dysfunction is one of the most prevalent and distressing adverse effects of serotonin reuptake inhibitor therapy, affecting a substantial proportion of patients across multiple domains including libido, arousal, and orgasm. The mechanisms underlying serotonergic sexual dysfunction are complex and involve serotonin-mediated inhibition of the spinal and supraspinal pathways that mediate sexual response. Delayed orgasm, decreased libido, and erectile dysfunction are the most commonly reported sexual side effects, and while some tolerance may develop over time, many patients experience persistent sexual difficulties throughout treatment. Management strategies include dose reduction, switching to an antidepressant with a lower incidence of sexual side effects such as bupropion, or the addition of an adjunctive agent to counteract the serotonergic effects on sexual function. The impact of sexual dysfunction on quality of life and treatment adherence should not be underestimated, and proactive discussion of sexual side effects as part of routine follow-up care can facilitate timely identification and management.
Safety considerations and risk assessment
The safety of Fluoxetine has been characterized through decades of clinical use and post-marketing surveillance. The most significant safety concern associated with Fluoxetine and other serotonin reuptake inhibitors is the potential for increased suicidal ideation and behavior, particularly in children, adolescents, and young adults during the initial phase of treatment. Meta-analyses of placebo-controlled trials conducted by regulatory agencies identified a small but statistically significant increase in the risk of suicidal thinking and behavior among patients under the age of twenty-five receiving antidepressant therapy. The absolute risk increase is small, estimated at approximately one to two additional cases per thousand treated patients, and the relationship between antidepressant therapy and suicide risk at the population level is complex, with ecological studies suggesting a net protective effect of increased antidepressant prescribing on suicide rates.
Serotonin syndrome is a potentially life-threatening condition that can occur when excessive serotonergic activity results from the combination of Fluoxetine with other serotonergic medications or from Fluoxetine overdose. The clinical presentation of serotonin syndrome encompasses a triad of altered mental status, autonomic instability, and neuromuscular abnormalities, ranging from mild symptoms such as tremor and diarrhea to severe manifestations including hyperthermia, rigidity, seizures, and death. The combination of Fluoxetine with monoamine oxidase inhibitors is absolutely contraindicated, and a washout period of at least five weeks between discontinuing Fluoxetine and starting a monoamine oxidase inhibitor is required, reflecting extended half-life of Fluoxetine and its active metabolite norfluoxetine. Other medications that increase serotonin levels, including other antidepressants, triptans, opioids such as tramadol and meperidine, and the over-the-counter supplement St. John’s Wort, should be used with caution or avoided in patients receiving Fluoxetine.
Bleeding risk is another safety consideration with Fluoxetine therapy, as serotonin plays an important role in platelet aggregation and hemostasis. Serotonin is actively transported into platelets by the serotonin transporter, the same protein targeted by Fluoxetine in the brain, and platelet serotonin contributes to the formation of the platelet plug at sites of vascular injury. By inhibiting the serotonin transporter on platelets, Fluoxetine impairs serotonin uptake and reduces the platelet serotonin content, resulting in impaired platelet aggregation and an increased risk of bleeding. The most common bleeding manifestations are cutaneous, presenting as easy bruising or petechiae, but gastrointestinal bleeding, epistaxis, and, rarely, intracranial hemorrhage have been reported. The bleeding risk is increased when Fluoxetine is used concurrently with other medications that affect hemostasis, including nonsteroidal anti-inflammatory drugs, aspirin, anticoagulants, and antiplatelet agents.
Discontinuation and withdrawal management
The discontinuation of Fluoxetine, like that of other serotonin reuptake inhibitors, can be associated with a withdrawal syndrome characterized by a constellation of physical and psychological symptoms. However, the extended elimination half-life of Fluoxetine and its active metabolite norfluoxetine confers a unique advantage in this regard, as the gradual decline in drug levels over several weeks following discontinuation minimizes the intensity and duration of withdrawal symptoms compared to shorter-acting antidepressants such as paroxetine or venlafaxine. Many patients can discontinue Fluoxetine without experiencing significant withdrawal effects, particularly when the medication has been tapered gradually over several weeks. This self-tapering property of Fluoxetine is one of the practical advantages that has contributed to its enduring popularity in clinical practice.
When withdrawal symptoms do occur, they may include dizziness, vertigo, ataxia, sensory disturbances including electric shock sensations and paresthesias, nausea, vomiting, diarrhea, headache, irritability, and vivid dreams or nightmares. These symptoms typically emerge within a few days to a week after the last dose, peak in intensity over one to two weeks, and gradually resolve over several weeks as the nervous system readapts to the absence of the medication. The management of withdrawal symptoms involves patient education about the expected course, reassurance that the symptoms are temporary, and, if necessary, the reinstatement of Fluoxetine at the previously effective dose followed by slower tapering. For patients who experience significant difficulty with discontinuation, the substitution of Fluoxetine for a shorter-acting antidepressant can serve as a bridging strategy, leveraging Fluoxetine’s extended half-life to facilitate a smoother transition off serotonergic medication.
Special populations and individualized treatment
The use of Fluoxetine during pregnancy requires careful consideration of the potential benefits of treating maternal depression against the potential risks to the developing fetus. Untreated depression during pregnancy is associated with adverse outcomes including poor prenatal care, inadequate nutrition, increased substance use, and an elevated risk of postpartum depression, which carries its own risks for both mother and infant. The balance of evidence suggests that Fluoxetine is not a major teratogen, and the absolute risk of congenital malformations associated with in utero exposure is small. However, exposure to serotonin reuptake inhibitors late in pregnancy has been associated with an increased risk of neonatal adaptation syndrome, characterized by respiratory distress, feeding difficulties, jitteriness, and irritability in the newborn. These symptoms are generally transient and self-limited, resolving within days to weeks without long-term sequelae.
Pediatric and adolescent patients represent a population in whom the risk-benefit calculus of Fluoxetine therapy requires particularly careful deliberation. Fluoxetine has demonstrated efficacy in the treatment of major depressive disorder and obsessive-compulsive disorder in children and adolescents, and it remains one of the preferred antidepressants for these age groups. However, the increased risk of suicidal ideation and behavior observed in younger patients receiving antidepressant therapy necessitates close monitoring, particularly during the initial weeks of treatment and following dose adjustments. The involvement of families in treatment planning and monitoring, combined with regular follow-up visits to assess clinical response and emergent side effects, is best practice in the pharmacological management of pediatric mood and anxiety disorders.
Elderly patients present unique considerations in Fluoxetine therapy, including age-related changes in drug metabolism and elimination, increased sensitivity to serotonergic side effects, and a higher prevalence of comorbid medical conditions and concomitant medications. Lower starting doses, typically 10 milligrams daily, and slower dose titration are generally recommended for geriatric patients. Particular attention should be paid to the risk of hyponatremia, which is more common in elderly patients receiving serotonin reuptake inhibitors and can present with confusion, lethargy, and, in severe cases, seizures. The increased risk of falls and fractures associated with antidepressant use in the elderly necessitates vigilance and the implementation of fall prevention strategies. Despite these considerations, the effective treatment of depression in late life can yield substantial improvements in quality of life, functional status, and overall health outcomes.
The therapeutic alliance and treatment engagement
The relationship between the prescribing clinician and the patient receiving Fluoxetine therapy is a critical determinant of treatment engagement, adherence, and ultimate clinical outcome. The collaborative therapeutic alliance, characterized by mutual respect, shared decision-making, and open communication, provides the foundation for effective depression treatment. Patients who feel heard, understood, and respected by their healthcare provider are more likely to adhere to treatment recommendations, report side effects honestly, and persist with therapy through the initial weeks when the antidepressant effects of Fluoxetine have not yet become apparent. The clinician’s ability to convey hope without making unrealistic promises, to normalize the challenges of treatment, and to maintain a non-judgmental stance toward the patient’s experiences and emotions contributes to the healing potential of the therapeutic encounter.
The initial weeks of Fluoxetine therapy represent a critical period for treatment engagement, as the side effects of the medication are often most pronounced during this time while the therapeutic benefits have not yet materialized. The activating effects of Fluoxetine, including increased anxiety, agitation, and insomnia, can be particularly challenging for patients whose depression involves prominent anxiety or psychomotor agitation. Patients should be forewarned about these potential effects and reassured that they are typically transient and manageable. The establishment of a follow-up plan, including a scheduled phone call or visit within the first one to two weeks of treatment, can provide an opportunity to assess tolerability, address emerging concerns, and reinforce the importance of continued therapy. The availability of the clinician during this vulnerable period can make the difference between successful treatment engagement and premature discontinuation.
The management of expectations is an essential component of the therapeutic alliance in Fluoxetine therapy. Patients should understand that the full antidepressant effects of Fluoxetine typically take four to six weeks to become apparent, and that the initial improvement may be partial rather than complete. The concept of response, defined as a fifty percent or greater reduction in depressive symptoms, should be distinguished from remission, which is the virtual absence of depressive symptoms and the return to premorbid levels of functioning. The goal of treatment is remission rather than mere response, and achieving this goal may require dose optimization, augmentation strategies, or, in some cases, a switch to an alternative antidepressant. The collaborative setting of realistic treatment goals, with acknowledgment of the potential for both improvement and limitations, can help prevent the disappointment and demoralization that can occur when expectations exceed what pharmacotherapy can realistically deliver.
Fluoxetine and the spectrum of anxiety disorders
While the primary FDA-approved indications for Fluoxetine center on depressive disorders, obsessive-compulsive disorder, bulimia nervosa, and premenstrual dysphoric disorder, the medication has been used in clinical practice for the treatment of various anxiety disorders. Panic disorder, characterized by recurrent unexpected panic attacks and persistent concern about future attacks or their consequences, responds to serotonin reuptake inhibitor therapy, and Fluoxetine has demonstrated efficacy in reducing panic attack frequency and anticipatory anxiety. The activating effects of Fluoxetine can initially exacerbate panic symptoms, and a low starting dose, typically 10 milligrams daily, with gradual upward titration is recommended for patients with panic disorder to minimize this risk. The concurrent use of a benzodiazepine during the initial weeks of treatment can provide symptom relief while the antidepressant effects of Fluoxetine develop, after which the benzodiazepine can be tapered and discontinued.
Social anxiety disorder, characterized by marked fear or anxiety about social situations in which the individual may be scrutinized by others, has been effectively treated with Fluoxetine in clinical practice, though large-scale controlled trials specifically supporting this indication are limited. Generalized anxiety disorder, characterized by excessive anxiety and worry occurring more days than not for at least six months, responds to serotonergic antidepressants, and Fluoxetine is among the agents used for this condition. The efficacy of Fluoxetine across the depression-anxiety spectrum reflects substantial overlap in the neurobiology of these conditions and the common involvement of serotonergic pathways in both mood and anxiety regulation. The selection of Fluoxetine for a patient with comorbid depression and anxiety can address both conditions with a single agent, simplifying the medication regimen and potentially improving adherence.
Fluoxetine in holistic mental health care
The optimal treatment of depression and anxiety disorders extends beyond pharmacotherapy to encompass a range of evidence-based interventions that address the psychological, social, and behavioral dimensions of mental health. Psychotherapy, including cognitive behavioral therapy, interpersonal therapy, and behavioral activation, has demonstrated efficacy comparable to pharmacotherapy for many patients with mild to moderate depression, and the combination of medication and psychotherapy often produces superior outcomes to either treatment alone, particularly for patients with chronic or severe depression. The integration of psychotherapy into the treatment plan provides patients with skills and strategies for managing depressive thoughts, behaviors, and interpersonal difficulties that extend beyond the period of active pharmacological treatment, potentially reducing the risk of relapse and recurrence. Patients receiving Fluoxetine should be offered referral for psychotherapy when appropriate and should be informed about the evidence supporting combined treatment approaches.
Lifestyle interventions that support mental health are important adjuncts to Fluoxetine therapy and can enhance treatment outcomes. Regular aerobic exercise has been shown to have antidepressant effects comparable to those of medication in some studies, and even modest levels of physical activity can improve mood, reduce anxiety, and enhance self-esteem. Adequate sleep, which is often disrupted in depression, supports emotional regulation and cognitive function, and attention to sleep hygiene can complement the therapeutic effects of Fluoxetine. Nutritional considerations, including adequate intake of omega-3 fatty acids, B vitamins, and vitamin D, may influence mood, though the evidence for specific dietary interventions in depression remains less robust than that for exercise. The management of comorbid substance use, including alcohol and recreational drugs, is essential, as these substances can worsen depression and interfere with the therapeutic response to antidepressant medication. A holistic approach to mental health that addresses these lifestyle factors alongside pharmacotherapy offers the best chance for sustained recovery and wellbeing.
The evolving understanding of depression and its treatment
The scientific understanding of depression has evolved considerably since the introduction of Fluoxetine, moving beyond the simple monoamine deficiency model to encompass a more nuanced appreciation of the neurobiological, psychological, and social processes that contribute to depressive illness. Neuroplasticity, the ability of the brain to reorganize its structure and function in response to experience, has emerged as a central concept in the pathophysiology of depression and the mechanism of antidepressant action. Chronic stress and depression are associated with reduced neuroplasticity in key brain regions, including the hippocampus and prefrontal cortex, and effective treatments, including both pharmacotherapy and psychotherapy, appear to enhance neuroplasticity and promote the growth and survival of neurons and synaptic connections. The neurotrophic hypothesis of depression, which implicates reduced expression of brain-derived neurotrophic factor and other neurotrophic factors in the pathophysiology of depression, provides a framework for understanding how Fluoxetine and other antidepressants, which increase neurotrophin expression, exert their therapeutic effects over the weeks to months required for neuroplastic changes to consolidate.
The recognition that depression is a heterogeneous condition with multiple underlying pathophysiological mechanisms has motivated efforts to identify biomarkers that can predict treatment response and guide the selection of antidepressant therapy. Inflammatory biomarkers, including C-reactive protein and pro-inflammatory cytokines, have been associated with depression and with differential response to various antidepressant classes, suggesting that patients with elevated inflammatory markers may respond differently to serotonergic agents like Fluoxetine than to agents that target other neurotransmitter systems. Neuroimaging markers, including structural and functional measures of prefrontal, limbic, and striatal circuitry, hold promise for identifying the neural signatures of treatment response. While biomarker-guided treatment selection remains primarily in the domain of research, the trajectory of psychiatric medicine is toward increasing personalization, with the goal of matching each patient with the treatment most likely to be effective and well-tolerated for their specific form of depression. Fluoxetine, as one of the original agents in the selective serotonin reuptake inhibitor class, will continue to play an important role in the evolving landscape of depression treatment.