Olanzapine (Zyprexa)

Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.

About Olanzapine

What it is

Olanzapine is an antipsychotic that blocks dopamine and serotonin receptors, as well as histamine and other receptors. It is used for schizophrenia and for mania and maintenance in bipolar disorder, and at low doses for nausea during chemotherapy. Weight gain and metabolic changes are common side effects. It is sold as Zyprexa, among other names.

How genes come into it

Olanzapine is broken down mainly by the liver enzyme CYP1A2, with help from UGT1A4 and FMO3; smoking speeds CYP1A2 up and lowers olanzapine levels. Studies have looked at CYP1A2 and CYP3A43 variants for blood levels, at the transporter ABCB1, and at dopamine and serotonin receptor genes (DRD2, HTR2A, HTR2C) for response and for weight gain, with mixed results. There is no CPIC or DPWG guideline.

What research found

Every published finding on gene variants and Olanzapine. Upload your DNA file to see which of these rows apply to you.

Rated evidence (73 rated variants)

PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.

HTR2C rs3813929: Level 3. Toxicity: Mental Disorders, Schizophrenia. 11.

HTR2C rs518147: Level 3. Toxicity: Schizophrenia, Weight gain. 5.

CYP3A43 rs472660: Level 3. Metabolism/PK: Schizophrenia. 2.

GIPR rs10423928: Level 3. Toxicity: Schizophrenia. 2.

Metabolism (89 findings)

Studies of how quickly the body processes this medication.

ABCB1 rs3842: Allele T is associated with increased clearance of olanzapine in healthy individuals as compared to allele C.

CYP1A2 rs35694136: Genotype T/del is associated with increased concentrations of olanzapine in people with Schizophrenia as compared to genotype TT.

CYP1A2 rs762551: Genotype AA is associated with decreased concentrations of olanzapine in people with Schizophrenia as compared to genotypes AC + CC.

CYP2C9 CYP2C9 poor metabolizers: CYP2C9 poor metabolizer is associated with increased exposure to olanzapine in healthy individuals as compared to CYP2C9 normal metabolizer and intermediate metabolizer.

Response (54 findings)

Studies of how well it worked in people carrying a variant.

rs12610827: Allele T is associated with increased clinical benefit to olanzapine in people with Schizophrenia as compared to allele G.

ATP1A2 rs6688363: Allele T is associated with decreased response to olanzapine in people with Schizophrenia as compared to allele C.

BDNF rs6265: Genotype CC is associated with increased response to olanzapine in people with Schizophrenia as compared to genotypes CT + TT.

CSMD1 rs17070785: Allele A is associated with response to olanzapine in people with Schizophrenia.

Dosing (6 findings)

Studies of how much of the drug people needed or tolerated.

CHAT rs1880676: Allele A is associated with increased response to olanzapine in people with Schizophrenia as compared to allele G.

CYP3A43 rs472660: Genotype AA is associated with increased clearance of olanzapine in people with Schizophrenia as compared to genotypes AG + GG.

IL1A rs11677416: Allele C is associated with increased response to olanzapine in people with Schizophrenia as compared to allele T.

SLC26A9 rs11240594: Allele A is associated with increased response to olanzapine in people with Schizophrenia as compared to allele G.

Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.

Related Drugs

More drugs from the same category

Abilify (Antipsychotics)

Antipsychotics (class) (Antipsychotics)

Bromperidol (Antipsychotics)

Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.

Back to Medications

Content updated September 2026.

ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.

Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026

Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com