Remeron vs. Fluoxetine

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

Key Takeaways

  • Remeron tends to cause sedation and increased appetite, while fluoxetine is more likely to cause insomnia and reduced appetite.

  • Fluoxetine has FDA approval for more conditions, including OCD, bulimia, and panic disorder, while Remeron is approved only for depression.

  • Both carry a boxed warning for increased suicidal thoughts in young people and can cause serotonin syndrome when combined with other serotonergic drugs.

Remeron vs. Fluoxetine Drug Summary

Remeron

Remeron (mirtazapine) is a tetracyclic antidepressant approved for major depressive disorder in adults. It is taken once daily, usually at night, and tends to cause more sedation at lower doses than at higher ones. It is also used off-label for insomnia, anxiety, and appetite stimulation.

Fluoxetine

Fluoxetine is an SSRI approved for major depressive disorder, OCD, bulimia nervosa, and panic disorder in adults, and for depression and OCD in children. It is taken once daily, and its long-acting active metabolite also allows a once-weekly maintenance option. It is one of the most established and widely used antidepressants available.

Remeron vs. Fluoxetine Side Effects

Remeron

Most common
somnolence (up to 54%)
dry mouth (up to 25%)
increased appetite (up to 17%)
constipation (up to 13%)

Fluoxetine

Most common
insomnia (up to 33%)
nausea (up to 21%)
headache (up to 21%)
somnolence (up to 13%)

Remeron vs. Fluoxetine Dosage

Remeron

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 15 mg once daily At the start
Maximum dose 45 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

Remeron vs. Fluoxetine Indications

Remeron

Remeron is FDA-approved only for major depressive disorder in adults. Off-label, prescribers sometimes use it for insomnia, anxiety, or to stimulate appetite in patients who are losing weight.

  • Major depressive disorder in adults

  • Off-label: insomnia

  • Off-label: anxiety disorders

  • Off-label: appetite or weight stimulation

  • Off-label: nausea in pregnancy

Fluoxetine

Fluoxetine is FDA-approved for a wider range of conditions, including depression, OCD, bulimia nervosa, and panic disorder, in both adults and children. It is also combined with olanzapine for bipolar depression and treatment-resistant depression.

  • Major depression in adults and children 8+

  • Obsessive-compulsive disorder in adults and children 7+

  • Bulimia nervosa in adults

  • Panic disorder in adults

  • Off-label: premenstrual dysphoric disorder

Remeron vs. Fluoxetine Pros and Cons

Remeron

Remeron's sedating profile makes it a useful option for depression with insomnia, but its strong effects on appetite and weight are a common reason patients stop taking it. It is approved only for depression, so it offers fewer treatment options than fluoxetine.

Pros

  • Sedating effect can improve sleep, often dosed at night

  • Less likely to cause sexual side effects than SSRIs

  • Available as an orally disintegrating tablet

  • Can help stimulate appetite in underweight patients

Cons

  • Significant weight gain and appetite increase are common

  • Sedation can impair daytime alertness, especially early on

  • Rare risk of severe neutropenia or agranulocytosis

  • Only FDA-approved for depression, not other conditions

Fluoxetine

Fluoxetine's long history and broad FDA approval make it a flexible choice for depression, OCD, and several other conditions. Its energizing profile can cause insomnia for some patients, in contrast to Remeron's sedating effect.

Pros

  • FDA-approved for OCD, bulimia, and panic disorder too

  • Approved for children as young as 7 for OCD, 8 for depression

  • Once-weekly maintenance dosing option available

  • Long safety track record since 1987 approval

Cons

  • Insomnia and nausea are common early side effects

  • Not sedating, so it doesn't help with sleep problems

  • Long half-life means interactions can persist after stopping

  • Not used off-label for appetite stimulation or sedation

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