Zoloft vs. Fluoxetine

See how Zoloft and Fluoxetine compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Zoloft and fluoxetine are both SSRIs, but Zoloft carries FDA approval for PTSD, social anxiety disorder, and PMDD, conditions fluoxetine's label does not cover.

  • Fluoxetine's long-acting metabolite allows a once-weekly maintenance option and eases missed doses, while Zoloft is taken daily and clears the body faster.

  • Both drugs share nausea, headache, insomnia, and diarrhea as common side effects, though fluoxetine shows a notably higher insomnia rate in trials.

Zoloft vs. Fluoxetine Drug Summary

Zoloft

Zoloft (sertraline) is a selective serotonin reuptake inhibitor (SSRI) used to treat major depressive disorder, OCD, panic disorder, PTSD, social anxiety disorder, and premenstrual dysphoric disorder. It is taken once a day, usually starting at 25 mg or 50 mg, with the dose raised as needed up to 200 mg.

Fluoxetine

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) approved for major depressive disorder, OCD, bulimia nervosa, panic disorder, and certain bipolar depression when combined with olanzapine. It starts at 10 mg to 20 mg once daily and can be raised to 80 mg a day, with a once-weekly 90 mg option for maintenance.

Zoloft vs. Fluoxetine Side Effects

Zoloft

Most common
Nausea (up to 26%)
Diarrhea (up to 20%)
Somnolence (up to 13%)
Dry mouth (up to 14%)

Fluoxetine

Most common
Nausea (up to 21%)
Diarrhea (up to 12%)
Somnolence (up to 13%)
Insomnia (up to 33%)

Zoloft vs. Fluoxetine Dosage

Zoloft

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 25-50 mg once daily Week 1
Maximum dose 50-200 mg once daily If needed
Dose changes 2 increases As tolerated

Fluoxetine

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 10 mg once daily Week 1
Maximum dose 90 mg once weekly If needed
Dose changes 4 increases Every week

Zoloft vs. Fluoxetine Indications

Zoloft

Zoloft is FDA-approved for major depressive disorder, OCD, panic disorder, PTSD, social anxiety disorder, and premenstrual dysphoric disorder. It is one of the few SSRIs approved specifically for PTSD and social anxiety disorder.

  • Major depressive disorder in adults

  • OCD in adults and children ages 6-17

  • Panic disorder in adults

  • PTSD in adults

  • Social anxiety disorder and PMDD in adults

Fluoxetine

Fluoxetine is FDA-approved for major depressive disorder, OCD, bulimia nervosa, and panic disorder. It also has approval, in combination with olanzapine, for depressive episodes of bipolar I disorder and treatment-resistant depression.

  • Major depressive disorder in adults and kids 8-18

  • OCD in adults and children ages 7-17

  • Bulimia nervosa in adults

  • Panic disorder in adults

  • Bipolar depression, with olanzapine

Zoloft vs. Fluoxetine Pros and Cons

Zoloft

Zoloft carries FDA approval for a wider range of anxiety-related conditions, including PTSD and social anxiety disorder. It has a shorter half-life than fluoxetine, so it leaves the body faster but can cause more noticeable effects if a dose is skipped.

Pros

  • FDA-approved for PTSD, social anxiety disorder, and PMDD

  • Shorter half-life clears the body faster if a switch is needed

  • Long track record with well-documented dosing across many conditions

Cons

  • No once-weekly maintenance dosing option

  • Shorter half-life raises discontinuation symptom risk if stopped abruptly

  • Oral solution contains alcohol, so it cannot be combined with disulfiram

Fluoxetine

Fluoxetine's long-acting metabolite smooths out missed doses and offers a once-weekly maintenance option not available with sertraline. Its FDA-approved anxiety indications are narrower, but it includes a combination option for treatment-resistant and bipolar depression.

Pros

  • Once-weekly maintenance dosing option after initial daily use

  • Long half-life makes missed doses less disruptive

  • Only SSRI combination approved for treatment-resistant depression

Cons

  • Not FDA-approved for PTSD, social anxiety disorder, or PMDD

  • Higher reported insomnia rate in trials than sertraline

  • Long half-life means it takes longer to clear if side effects occur

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