Medication approval journey

olanzapine (Zyprexa)

Approved for Schizophrenia in adults

FDA approvedAntipsychoticTaper risk: high

Before changing anything

Stopping abruptly can be dangerous — never do it without medical supervision

Do not stop an antipsychotic abruptly. Abrupt withdrawal can cause rebound or supersensitivity psychosis and withdrawal movement disorders, and relapse risk is highest with the fastest reductions. Any change should be a slow, prescriber-supervised taper.

How long the trials actually ran

The longest trial behind the olanzapine approval ran 6 weeks.

The gap between how long the trials ran and how long people actually take these medications is the single most important thing on this page. It is not evidence that longer use is unsafe or ineffective. It is evidence that longer use was not what got tested.

The boxed warning

The strongest warning the FDA puts on a label, reproduced word for word — not our summary of it.

WARNING: INCREASED MORTALITY IN ELDERLY PATIENTS WITH DEMENTIA-RELATED PSYCHOSIS Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Analyses of seventeen placebo-controlled trials (modal duration of 10 weeks), largely in patients taking atypical antipsychotic drugs, revealed a risk of death in drug-treated patients of between 1.6 to 1.7 times the risk of death in placebo-treated patients. Over the course of a typical 10-week controlled trial, the rate of death in drug-treated patients was about 4.5%, compared to a rate of about 2.6% in the placebo group. Although the causes of death were varied, most of the deaths appeared to be either cardiovascular (e.g., heart failure, sudden death) or infectious (e.g., pneumonia) in nature. Observational studies suggest that, similar to atypical antipsychotic drugs, treatment with conventional antipsychotic drugs may increase mortality. The extent to which the findings of increased mortality in observational studies may be attributed to the antipsychotic drug as opposed to some characteristic(s) of the patients is not clear. Olanzapine for injection is not approved for the treatment of patients with dementia-related psychosis [see Warnings and Precautions ( 5.1 ), Use in Specific Populations ( 8.5 ), and Patient Counseling Information ( 17 )] . WARNING: INCREASED MORTALITY IN ELDERLY PATIENTS WITH DEMENTIA-RELATED PSYCHOSIS See full prescribing information for complete boxed warning. Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Olanzapine for Injection is not approved for the treatment of patients with dementia-related psychosis. ( 5.1 , 8.5 , 17 )

FDA label effective August 25, 2026 — read the full label on DailyMed

How many Americans take olanzapine

Survey-based federal estimates, published with a lag of about two years. They count prescriptions filled, not outcomes.

3,642,411
prescriptions in the United States (2024)
668,979
people filling them (2024)

Prescriptions are up 51% since 2014. Whatever you decide about olanzapine, you are deciding alongside about 668,979 other people this year.

Source: ClinCalc DrugStats (Medical Expenditure Panel Survey (MEPS), Agency for Healthcare Research and Quality), CC BY-SA 4.0, release 2026.08.

What people report to the FDA about olanzapine

Read this before the numbers.

Anyone can file an adverse event report — patients, doctors, manufacturers — and nobody verifies that the drug caused what was reported. There is no denominator: tens of millions of prescriptions generate reports at an unknowable rate, and reporting rises with news coverage, not necessarily with harm. Counts below are report volumes, not rates, and cannot be compared between drugs. The FDA itself says not to use this data to make medical decisions — we show it because you deserve to see what is in the public record, with its limits stated plainly.

109,181
reports mentioning olanzapine, all time
93,127
filed as serious (a report-level flag covering every drug and outcome in the report)

Most-reported reactions

  • Drug ineffective7,452
  • Weight increased6,931
  • Off label use6,256
  • Diabetes mellitus5,413
  • Drug interaction4,208
  • Toxicity to various agents4,207
  • Nausea4,139
  • Somnolence4,133
  • Fatigue3,686
  • Anxiety3,517

“Drug ineffective” ranking this high is worth noticing: a report of not being helped counts as an adverse event too, and people file them in large numbers.

Source: FDA Adverse Event Reporting System (FAERS), via openFDA, data through 2026-07-30.

Known interactions, from the label

The FDA label’s interactions section, verbatim. A pharmacist checking your actual medication list beats any published list — including this one.

Read the label’s interactions section

7 DRUG INTERACTIONS The risks of using olanzapine in combination with other drugs have not been extensively evaluated in systematic studies. Diazepam: May potentiate orthostatic hypotension. ( 7.1 , 7.2 ) Alcohol: May potentiate orthostatic hypotension. ( 7.1 ) Carbamazepine: Increased clearance of olanzapine. ( 7.1 ) Fluvoxamine: May increase olanzapine levels. ( 7.1 ) CNS Acting Drugs: Caution should be used when taken in combination with other centrally acting drugs and alcohol. ( 7.2 ) Antihypertensive Agents: Enhanced antihypertensive effect. ( 7.2 ) Levodopa and Dopamine Agonists: May antagonize levodopa/dopamine agonists. ( 7.2 ) Lorazepam (IM): Increased somnolence with IM olanzapine. ( 7.2 ) Other Concomitant Drug Therapy: When using olanzapine in combination with lithium or valproate, refer to the Drug Interactions sections of the package insert for those products. ( 7.2 )

7.1 Potential for Other Drugs to Affect Olanzapine Diazepam — The co-administration of diazepam with olanzapine potentiated the orthostatic hypotension observed with olanzapine [see Drug Interactions ( 7.2 )] . Cimetidine and Antacids — Single doses of cimetidine (800 mg) or aluminum- and magnesium-containing antacids did not affect the oral bioavailability of olanzapine. Inducers of CYP1A2 — Carbamazepine therapy (200 mg bid) causes an approximately 50% increase in the clearance of olanzapine. This increase is likely due to the fact that carbamazepine is a potent inducer of CYP1A2 activity. Higher daily doses of carbamazepine may cause an even greater increase in olanzapine clearance. Alcohol — Ethanol (45 mg/70 kg single dose) did not have an effect on olanzapine pharmacokinetics. The co-administration of alcohol (i.e., ethanol) with olanzapine potentiated the orthostatic hypotension observed with olanzapine [see Drug Interactions ( 7.2 )] . Inhibitors of CYP1A2 Fluvoxamine: Fluvoxamine, a CYP1A2 inhibitor, decreases the clearance of olanzapine. This results in a mean increase in olanzapine Cmax following fluvoxamine of 54% in female nonsmokers and 77% in male smokers. The mean increase in olanzapine AUC is 52% and 108%, respectively. Lower doses of olanzapine should be considered in patients receiving concomitant treatment with fluvoxamine. Inhibitors of CYP2D6 Fluoxetine: Fluoxetine (60 mg single dose or 60 mg daily dose for 8 days) causes a small (mean 16%) increase in the maximum concentration of olanzapine and a small (mean 16%) decrease in olanzapine clearance. The magnitude of the impact of this factor is small in comparison to the overall variability between individuals, and therefore dose modification is not routinely recommended. Warfarin — Warfarin (20 mg single dose) did not affect olanzapine pharmacokinetics [see Drug Interactions ( 7.2 )] . Inducers of CYP1A2 or Glucuronyl Transferase — Omeprazole and rifampin may cause an increase in olanzapine clearance. Charcoal — The administration of activated charcoal (1 g) reduced the Cmax and AUC of oral olanzapine by about 60%. As peak olanzapine levels are not typically obtained until about 6 hours after dosing, charcoal may be a useful treatment for olanzapine overdose. Anticholinergic Drugs — Concomitant treatment with olanzapine and other drugs with anticholinergic activity can increase the risk for severe gastrointestinal adverse reactions related to hypomotility. Olanzapine should be used with caution in patients receiving medications having anticholinergic (antimuscarinic) effects [see Warnings and Precautions ( 5.14 )] .

7.2 Potential for Olanzapine to Affect Other Drugs CNS Acting Drugs — Given the primary CNS effects of olanzapine, caution should be used when olanzapine is taken in combination with other centrally acting drugs and alcohol. Antihypertensive Agents — Olanzapine, because of its potential for inducing hypotension, may enhance the effects of certain antihypertensive agents. Levodopa and Dopamine Agonists — Olanzapine may antagonize the effects of levodopa and dopamine agonists. Lorazepam (IM) — Administration of intramuscular lorazepam (2 mg) 1 hour after intramuscular olanzapine for injection (5 mg) did not significantly affect the pharmacokinetics of olanzapine, unconjugated lorazepam, or total lorazepam. However, this co-administration of intramuscular lorazepam and intramuscular olanzapine for injection added to the somnolence observed with either drug alone [see Warnings and Precautions ( 5.7 )] . Lithium — Multiple doses of olanzapine (10 mg for 8 days) did not influence the kinetics of lithium. Therefore, concomitant olanzapine administration does not require dosage adjustment of lithium [see Warnings and Precautions ( 5.16 )] . Valproate — Olanzapine (10 mg daily for 2 weeks) did not affect the steady state plasma concentrations of valproate. Therefore, concomitant olanzapine administration does not require dosage adjustment of valproate [see Warnings and Precautions ( 5.16 )] . Effect of Olanzapine on Drug Metabolizing Enzymes — In vitro studies utilizing human liver microsomes suggest that olanzapine has little potential to inhibit CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A. Thus, olanzapine is unlikely to cause clinically important drug interactions mediated by these enzymes. Imipramine — Single doses of olanzapine did not affect the pharmacokinetics of imipramine or its active metabolite desipramine. Warfarin — Single doses of olanzapine did not affect the pharmacokinetics of warfarin [see Drug Interactions ( 7.1 )] . Diazepam — Olanzapine did not influence the pharmacokinetics of diazepam or its active metabolite N-desmethyldiazepam. However, diazepam co-administered with olanzapine increased the orthostatic hypotension observed with either drug given alone [see Drug Interactions ( 7.1 )] . Alcohol — Multiple doses of olanzapine did not influence the kinetics of ethanol [see Drug Interactions ( 7.1 )] . Biperiden — Multiple doses of olanzapine did not influence the kinetics of biperiden. Theophylline — Multiple doses of olanzapine did not affect the pharmacokinetics of theophylline or its metabolites.

FDA label for olanzapine, effective August 25, 2026 — DailyMed.

Who pays for olanzapine

Two claims datasets and one survey, covering different populations with different instruments — they cannot be reconciled by arithmetic, and where their sum crowds the all-payer estimate, that is a finding about the estimates rather than a percentage.

Medicare Part D · claims · 2024Medicaid · claims floor · 2024All-payer · survey · 2024Commercially insured adults · not publishedChildren · no per-drug data
Medicare Part D
Read the under-65 group correctly before the numbers: Medicare before 65 means the disabled and dual-eligible population — among the sickest, highest-need people in the program — and reading their utilization as typical adult use would be a category error. The beneficiary total sums brand-level rows, so treat it as an upper bound on distinct people. 606,074 beneficiaries filled 3,986,220 claims in 2024 — 367,231 aged 65 and over, and 238,843 under 65.
Medicaid
At least 2,622,442 prescriptions in 2024 — a floor, because 405 of 1,561 national data rows are suppressed for privacy and contribute zero. Medicaid covers more children than any insurer in the country and publishes no age split — how much of this number is pediatric use is not knowable from public data.
All payers (survey estimate)
The MEPS-based estimate above puts the whole country at 3,642,411 prescriptions and 668,979 people in 2024. Subtracting the public programs from it would produce a number for everyone else — and we do not print that number, because subtracting a survey from claims counts manufactures precision that does not exist.
The population nobody counts
The commercially insured working-age adult — statistically, the likeliest person to be reading this page — is the one population with no public per-drug count anywhere. Private claims data exists and is sold, but nothing a patient can check is published. For children the record is thinner still: no public source counts pediatric use of olanzapine specifically; the closest the public record comes is condition-level treatment rates for children, which we have traced for one condition in how childhood ADHD got counted.

Sources: Medicare Part D Prescribers — by Geography and Drug, data.cms.gov, National rows, data year 2024 (published with ~17-month lag). Medicaid State Drug Utilization Data 2024, data.medicaid.gov, national aggregate rows. Retrieved 2026-09-01.

The approval, step by step

  1. Step 1

    What the approval was actually based on

    Which studies did the FDA rely on, how long did they run, and who was in them?

    The efficacy of oral olanzapine in the treatment of schizophrenia was established in 2 short-term (6-week) controlled trials of adult inpatients who met DSM III-R criteria for schizophrenia. A single haloperidol arm was included as a comparative treatment in 1 of the 2 trials, but this trial did not compare these 2 drugs on the full range of clinically relevant doses for both.

    FDA-approved labelling, 14 CLINICAL STUDIES 14.1 Schizophrenia — read the label on DailyMed

    Our reading

    Two six-week trials — the thinnest approval package of the antipsychotics here — and the label itself flags that the one head-to-head comparison did not test both drugs across their real dose ranges, so it cannot tell you olanzapine is better than the older drug it was priced against. Olanzapine causes more weight gain and more metabolic disturbance than almost anything else in psychiatry, and six weeks is not long enough to see it. Note also that the application is now held by Cheplapharm; the trials were Lilly's.

  2. Step 2

    The approval

    When was it approved, under what application, and by whose review?

    Approved
    September 30, 1996
    Application
    NDA020592
    Review
    STANDARD
    Original sponsor
    Eli Lilly and Company
    Holds it now
    Cheplapharm
    Label submissions since
    48

    Source: openFDA Drugs@FDA, original application ORIG-1

  3. Step 3

    What was added after it was on the market

    Which warnings arrived only after millions of people were already taking it?

  4. Step 4

    What independent research has found since

    What has been learned by people who were not selling it?

    We have not yet added independent post-approval research on olanzapine to the evidence library. Absence here means we have not covered it, not that none exists.

  5. Step 5

    What still is not known

    Which questions you might reasonably have has nobody answered yet?

    • Two trials, six weeks. This is the shortest and smallest antipsychotic package in the directory.
    • The label says the haloperidol comparison did not cover the full dose range of either drug. So on what basis is it the better choice?
    • Metabolic effects are the main reason people stop taking it, and they were not measurable inside six weeks.

The legal and safety record

Settled and adjudicated matters only, from primary sources — including the litigation that was decided for the manufacturer, and the cases this drug is verifiably not part of.

Read the olanzapine legal and safety record

Deciding about olanzapine?

Open olanzapine (Zyprexa) in Resolv

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Browse the evidence library