What Is Fluoxetine/Olanzapine (Symbyax)? Uses, Dosage, and What You Need to Know in 2026

Fluoxetine/Olanzapine — sold under the brand name Symbyax — is a prescription combination capsule that has two approved uses most patients and families need to understand: treating depressive episodes of bipolar I disorder and treating treatment-resistant depression. It holds the distinction of being the first medication ever FDA-approved specifically for treatment-resistant depression, receiving that indication in 2009.

This article covers everything patients need to know about Fluoxetine/Olanzapine in 2026 — what it is, what it treats, how to take it, and what to expect.

What Is Fluoxetine/Olanzapine (Symbyax)?

Symbyax is a fixed-dose combination capsule containing two active ingredients:

Olanzapine: An atypical antipsychotic (also marketed separately as Zyprexa). It works by blocking dopamine and serotonin receptors to help stabilize mood.

Fluoxetine: A selective serotonin reuptake inhibitor (SSRI) antidepressant (also marketed separately as Prozac). It raises serotonin levels in the brain to improve mood and emotional regulation.

The combination was developed because clinical research showed that pairing these two medications produced better antidepressant outcomes in bipolar depression than either drug alone — a 56.1% response rate for the combination versus 39% for olanzapine alone and 30.4% for placebo.

What Is Fluoxetine/Olanzapine Used For?

Fluoxetine/Olanzapine has two FDA-approved indications:

Acute depressive episodes in Bipolar I Disorder: Approved for adults and children ages 10 and older. Bipolar I disorder involves cycles of mania and severe depression — Symbyax specifically addresses the depressive episodes.

Treatment-resistant depression (TRD): Approved for adults with major depressive disorder (MDD) who have not responded to at least two separate antidepressant trials of adequate dose and duration in the current episode. Symbyax was the first drug approved by the FDA specifically for this purpose.

Symbyax is NOT approved for schizophrenia, dementia-related psychosis, or general anxiety — even though olanzapine alone may be used for some of these conditions.

Available Dosage Forms and Strengths

Fluoxetine/Olanzapine comes as oral capsules in five strength combinations (listed as olanzapine mg / fluoxetine mg):

3 mg / 25 mg

6 mg / 25 mg (most common starting dose for adults)

6 mg / 50 mg

12 mg / 25 mg

12 mg / 50 mg

Both brand-name Symbyax (Eli Lilly) and generic versions (Teva Pharmaceuticals, Par Pharmaceuticals) are available.

How Is Fluoxetine/Olanzapine Taken?

Fluoxetine/Olanzapine is taken once daily, typically in the evening. Taking it at bedtime can help manage the most common side effect — drowsiness — by allowing sleepiness to peak during sleep rather than the daytime. The medication can be taken with or without food.

What Is the Typical Dosage?

Adults:

Starting dose: 6 mg olanzapine / 25 mg fluoxetine once daily in the evening

Effective dose range: 6–12 mg olanzapine / 25–50 mg fluoxetine

Maximum studied dose: 18 mg / 75 mg

Children/Adolescents (ages 10–17, for bipolar I depression only):

Starting dose: 3 mg / 25 mg once daily in the evening

Maximum studied dose: 12 mg / 50 mg

Lower starting doses (3/25 or 6/25 mg) are recommended for patients predisposed to hypotension, those with liver problems, and patients who metabolize medications more slowly (female, elderly, nonsmoker).

How Long Does It Take to Work?

Clinical studies suggest that some patients begin to notice mood improvement within the first week of treatment with Symbyax. However, full antidepressant benefit typically takes several weeks to months. Do not stop the medication early if you don't see immediate results — and always talk to your prescriber before making any changes.

Is It a Controlled Substance?

No. Fluoxetine/Olanzapine (Symbyax) is not a controlled substance and has no DEA schedule. It does not have a recognized potential for abuse, addiction, or dependence. This means it can be prescribed without the special DEA requirements that apply to controlled substances, and it can be prescribed via telehealth.

Where Can You Find It?

Fluoxetine/Olanzapine requires a prescription and is not available over the counter. It is a niche combination product and may not be stocked at every pharmacy. medfinder.com can help you find which pharmacies near you have your specific dose in stock. For more context on why it can be hard to find, see our explainer on Symbyax availability.