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Classification: A

Drug products: Fluoxetin BMM Pharma, Fluoxetin Ebb, Fluoxetin Mylan, Fluoxetin Orifarm, Fluoxetin ratiopharm, Fluoxetin Sandoz, Fluoxetin STADA®, Fluoxetin Teva, Fluoxetine Accord, Fluoxetine Orion, Fluoxetine Vitabalans, Fontex, Fontex®, Prozac

ATC code: N06AB03

Substances: fluoxetine, fluoxetine hydrochloride


Some studies show that fluoxetine-treated women have higher recurrence rates than men, while other studies don’t show any sex differences in improvement or recurrence.
Prevalence of suicidal behavior was higher among fluoxetine-treated men than women in a large British register study.

Additional information

Depression is almost twice as common in women as in men [1]. Women have an earlier age of onset and increased duration of depressive episodes. Differences in neurobiology [2, 3], hormones, inflammatory markers, diagnostic tools, or health seeking behavior [4, 5] may be of importance.  Although depression is more prevalent in women, most preclinical studies on depression have used  male animals [2].

Women are two to three times more likely to suffer from an anxiety disorder [1]. Sex differences in symptomatology and comorbidity  may be due to genetic, hormonal, neurodevelopmental, environmental, and neurobiological factors [6].

Pharmacokinetics and dosing

Studies on differences between healthy adult men and women in fluoxetine pharmacokinetics have not been published. A small study of  elderly individuals (65-85 years; 11 men, 14 women) did not detect any  sex differences  in plasma concentrations, half-life or clearance of fluoxetine. However, women had 17% higher levels and slower elimination of  the active metabolite norfluoxetine [7].

In a study in children and adolescents diagnosed with major depressive disorder, obsessive-compulsive disorder, or generalized anxiety disorder (24 boys, 50 girls; ages 10-17 years), mean doses and mean serum concentrations were higher in girls than boys (week 8: 26.6 vs. 18.5 mg/day; 111.4 vs. 61.7 ng/ml). Sex differences could also be detected at week 12 [8]. However, other studies in children and adolescents using mean doses of 20 mg/day did  not demonstrate sex differences in serum concentrations of fluoxetine and its  active metabolite norfluoxetine [9, 10].


Major depressive disorder

Studies analyzing sex differences in fluoxetine response report are not consistent. Some studies show higher recurrence rates in fluoxetine-treated women than men [11,12], while other studies show no differences in improvement or recurrence [13-16]. It should be noted that most studies have a short study period and thus the clinically relevance of the results may not be relevant for the long term effect.An open-label 12-week study (266 men, 574 women) found no age- or sex differences in fluoxetine response (20 mg/day) [13,14]. In an cohort study in outpatients receiving fluoxetine 20 mg/day for 8 weeks (153 men, 176 women), rates of remission and reduction of depressive symptoms were similar in men and women and across ages [15]. Fluoxetine 20 mg/day was compared to maprotiline 100-200 mg/day in adult patients with severe unipolar depression in a 6-week randomized trial (in total 42 men, 59 women; on fluoxetine 23 men, 24 women). Men and women taking fluoxetine had equal improvement [16].Long-term studies show higher recurrence rates in women. In a post-hoc analysis of the PREVENT trial (105 men, 161 women on fluoxetine) the recurrence rates during a 12-month maintenance phase (28 men, 51 women on fluoxetine) were approximately 50% in women and 15% in men. However, during another 12 months after the maintenance phase, the recurrence rates were similar for men and women (20 men, 25 women on fluoxetine) [11]. It has to be kept in mind that the statistical power to detect any differences in the second part of this trial might have been too low to draw any conclusion.  Also, a RCT (260 men, 310 women) showed that women were more likely to relapse during the 6-month continuation and 6-month maintenance phases (hazard ratio 1.84) [12].No overall sex differences in SSRI (citalopram, escitalopram, fluoxetin) treatment response were found in a clinical study (59 men, 242 women), but menopausal women had worse outcome that non-menopausal women (95 menopausal women, 147 non-menopausal women) [17].Adolescents randomized to fluoxetine, cognitive behavior therapy, a combination of those or placebo were followed up for 63 months (in total 86 boys, 110 girls; on fluoxetine 48). Recurrence rates were 57% among girls and 33% among boys [18]. Similarly, a small study in children (65 boys, 37 girls, 7-18 years old) reported a higher odds of relapse in girls in the continuation phase (OR 8.86, 95%CI 1.83-42.78) [19]. However, the two studies used different score levels for definition of relapse on the CDRS-R (Children’s Depression Rating Scale). Contrary, the pharmaceutical company report that subgroup analyses did not show any differences in response between boys and girls or between age groups [20].

Obsessive Compulsive Disorder

According to the pharmaceutical company, subgroup analyses on outcome did not show any differences in response between boys and girls, men and women or between age groups [20].

Adverse effects

Data from the UK General Practice Research Database (GPRD) was used to analyze the risk of fatal overdose with SSRI (41 327 men, 93 669 women on fluoxetine). The prevalence of suicidal behavior in patients taking fluoxetine was higher in men than women (0.5% vs. 0.3%) [21].

Reproductive health issues

Sexual dysfunction is common in men and women on SSRI treatment and can affect all phases of the sexual response cycle. It is often underestimated since patients tend to underreport sexual adverse effects if not directly questioned [22, 23]. A meta-analysis consisting of 31 studies (in total 268 men and 801 women on fluoxetine) evaluating sexual dysfunction induced by antidepressants (citalopram, fluoxetine, paroxetine, sertraline, venlafaxine) showed that men treated with fluoxetine had higher odds of having desire dysfunction (OR 2.95) and orgasm dysfunction (OR 6.00) as compared to women [22]. Regarding teratogenic aspects, please consult the Drugs and Birth Defects Database (in Swedish, Janusmed fosterpåverkan).

Other information

Drug utilization of ten commonly prescribed antidepressants during the period 2009-2014 in Sweden, Denmark, Germany, and Spain were analyzed in a large register study (in total 4 833 774 initiators included). Women comprised the majority of initiators for all antidepressants studied. In Sweden, 73.5% of the initiators on fluoxetine were women [24].

Updated: 2022-06-13

Date of litterature search: 2022-04-21


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  3. Sramek JJ, Murphy MF, Cutler NR. Sex differences in the psychopharmacological treatment of depression. Dialogues Clin Neurosci. 2016;18(4):447-457. PubMed
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  8. Blázquez A, Mas S, Plana MT, Gassó P, Méndez I, Torra M et al. Plasma fluoxetine concentrations and clinical improvement in an adolescent sample diagnosed with major depressive disorder, obsessive-compulsive disorder, or generalized anxiety disorder. J Clin Psychopharmacol. 2014;34:318-26. PubMed
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  10. Wilens TE, Cohen L, Biederman J, Abrams A, Neft D, Faird N et al. Fluoxetine pharmacokinetics in pediatric patients. J Clin Psychopharmacol. 2002;22:568-75. PubMed
  11. Kornstein SG, Pedersen RD, Holland PJ, Nemeroff CB, Rothschild AJ, Thase ME et al. Influence of sex and menopausal status on response, remission, and recurrence in patients with recurrent major depressive disorder treated with venlafaxine extended release or fluoxetine: analysis of data from the PREVENT study. J Clin Psychiatry. 2014;75:62-8. PubMed
  12. McGrath PJ, Stewart JW, Quitkin FM, Chen Y, Alpert JE, Nierenberg AA et al. Predictors of relapse in a prospective study of fluoxetine treatment of major depression. Am J Psychiatry. 2006;163:1542-8. PubMed
  13. Quitkin FM, Stewart JW, McGrath PJ, Taylor BP, Tisminetzky MS, Petkova E et al. Are there differences between women's and men's antidepressant responses?. Am J Psychiatry. 2002;159:1848-54. PubMed
  14. McGrath PJ, Stewart JW, Petkova E, Quitkin FM, Amsterdam JD, Fawcett J et al. Predictors of relapse during fluoxetine continuation or maintenance treatment of major depression. J Clin Psychiatry. 2000;61:518-24. PubMed
  15. Cassano P, Soares CN, Cohen LS, Lyster AK, Fava M. Sex- and age-related differences in major depressive disorder with comorbid anxiety treated with fluoxetine. Arch Womens Ment Health. 2004;7:167-71. PubMed
  16. Martényi F, Dossenbach M, Mraz K, Metcalfe S. Gender differences in the efficacy of fluoxetine and maprotiline in depressed patients: a double-blind trial of antidepressants with serotonergic or norepinephrinergic reuptake inhibition profile. Eur Neuropsychopharmacol. 2001;11:227-32. PubMed
  17. Pinto-Meza A, Usall J, Serrano-Blanco A, Suárez D, Haro JM. Gender differences in response to antidepressant treatment prescribed in primary care Does menopause make a difference?. J Affect Disord. 2006;93:53-60. PubMed
  18. Curry J, Silva S, Rohde P, Ginsburg G, Kratochvil C, Simons A et al. Recovery and recurrence following treatment for adolescent major depression. Arch Gen Psychiatry. 2011;68:263-9. PubMed
  19. Kennard BD, Mayes TL, Chahal Z, Nakonezny PA, Moorehead A, Emslie GJ. Predictors and Moderators of Relapse in Children and Adolescents With Major Depressive Disorder. J Clin Psychiatry. 2018;79(2). PubMed
  20. Prozac (fluoxetine). DailyMed [www]. US National Library of Medicine. [updated 2019-05-24, cited 2022-04-21]. länk
  21. Mines D, Hill D, Yu H, Novelli L. Prevalence of risk factors for suicide in patients prescribed venlafaxine, fluoxetine, and citalopram. Pharmacoepidemiol Drug Saf. 2005;14:367-72. PubMed
  22. Serretti A, Chiesa A. Treatment-emergent sexual dysfunction related to antidepressants: a meta-analysis. J Clin Psychopharmacol. 2009;29:259-66. PubMed
  23. Lorenz T, Rullo J, Faubion S. Antidepressant-Induced Female Sexual Dysfunction. Mayo Clin Proc. 2016;91(9):1280-6. PubMed
  24. Forns J, Pottegård A, Reinders T, Poblador-Plou B, Morros R, Brandt L et al. Antidepressant use in Denmark, Germany, Spain, and Sweden between 2009 and 2014: Incidence and comorbidities of antidepressant initiators. J Affect Disord. 2019;249:242-252. PubMed
  25. Läkemedelsstatistik. Stockholm: Socialstyrelsen. 2015 [cited 2016-11-08.] Socialstyrelsens statistikdatabas

Authors: Linnéa Karlsson Lind

Reviewed by: Carl-Olav Stiller, Diana Rydberg

Approved by: Karin Schenck-Gustafsson