quetiapine (Seroquel)

How long the trials actually ran

The longest trial behind the quetiapine 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.

How many Americans take quetiapine

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

8,669,046

prescriptions in the United States (2024)

1,849,066

people filling them (2024)

Prescriptions are down 24% since 2014. Whatever you decide about quetiapine, you are deciding alongside about 1,849,066 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 quetiapine

191,484

reports mentioning quetiapine, all time

151,227

filed as serious (a report-level flag covering every drug and outcome in the report)

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.

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

Who pays for quetiapine

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

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. 1,488,315 beneficiaries filled 9,859,922 claims in 2024 — 1,039,853 aged 65 and over, and 448,462 under 65.

Medicaid

At least 6,033,466 prescriptions in 2024 — a floor, because 293 of 1,843 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 8,669,046 prescriptions and 1,849,066 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 quetiapine 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 SEROQUEL in the treatment of schizophrenia was established in 3 short-term (6-week) controlled trials of inpatients with schizophrenia who met DSM III-R criteria for schizophrenia...

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

   Our reading

   Three six-week trials in inpatients. Quetiapine is now very widely prescribed off-label at low doses for sleep and for anxiety — uses that appear in none of these trials and in no part of the approval, and therefore carry no approval-grade efficacy evidence at all.

2. Step 2

   The approval

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

   Approved

   September 26, 1997

   Application

   NDA020639

   Review

   STANDARD

   Original sponsor

   AstraZeneca (now Cheplapharm)

   Holds it now

   Cheplapharm

   Label submissions since

   49

   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?

   • Antipsychotics raise the risk of death in older people with dementia

     This is one of the clearest harm signals in psychiatric medicine, and it applies to a specific group: older adults with dementia-related psychosis. Pooling 17 placebo-controlled trials covering 5,106 patients over roughly 10 weeks, the risk of death was 1.6 to 1.7 times higher on an antipsychotic than on placebo — about 4.5% against 2.6%. Most deaths were cardiovascular or infectious, chiefly heart failure, sudden death and pneumonia.

     The FDA first applied this warning to the newer antipsychotics in 2005 and extended it to the older ones in 2008. No antipsychotic is approved for dementia-related psychosis.

     If this is being prescribed for an older relative with dementia, worth asking: what specific behaviour are we treating, what have we tried that is not a drug, what is the shortest time we can plan for, and when will we review stopping.

     RISPERDAL (risperidone) prescribing information — Boxed Warning: Increased Mortality in Elderly Patients with Dementia-Related Psychosis — U.S. Food and Drug Administration (approved labelling)

4. Step 4

   What independent research has found since

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

   • Comparative efficacy and tolerability of 32 oral antipsychotics for the acute treatment of adults with multi-episode…

     22 years after approval

     Across 402 randomized trials covering 53,463 adults with schizophrenia, quetiapine ranked mid-field of 32 antipsychotics for symptom reduction, with low rates of movement side effects but more sedation and a small QTc prolongation (about 3 ms) versus placebo.

     Worth asking

     Given quetiapine's middle-of-the-pack efficacy ranking, what made it the right antipsychotic for my situation compared with the alternatives?

     Comparative efficacy and tolerability of 32 oral antipsychotics for the acute treatment of adults with multi-episode schizophrenia: a systematic review and network meta-analysis — Huhn M, et al. (2019)

   • Second-generation antipsychotics for anxiety disorders

     13 years after approval

     Pooling 11 randomized trials (4,144 participants), people with generalized anxiety disorder were about twice as likely to respond to quetiapine as to placebo (odds ratio 2.21 across 4 trials, N=2,265), but quetiapine caused more weight gain, sedation, and dropouts from side effects — and this use is not FDA-approved.

     Worth asking

     If quetiapine was prescribed for anxiety, have we weighed its off-label benefit against the weight gain and sedation, and tried first-line anxiety treatments?

     Second-generation antipsychotics for anxiety disorders — Depping AM, et al. (2010)

   • Low-dose quetiapine is prescribed for sleep. Its metabolic effects were tested in 106,711 people

     26 years after approval

     Quetiapine is very often prescribed off-label at low doses for sleep and anxiety, on the reasoning that the metabolic problems seen at antipsychotic doses do not apply down there. Danish researchers tested that using national registers: 106,711 people who newly started quetiapine at 50 mg or less between 2008 and 2018, with blood results from the year before and the year after they started.

     What they found is worth reading carefully, because it does not flatten into a headline. Across everyone, triglycerides rose by about 5% and HDL — the cholesterol you want high — fell by about 2%. HbA1c did not change significantly, and total and LDL cholesterol actually went down.

     The part that matters is underneath that. Among people whose levels were normal before they started, HbA1c, total cholesterol and LDL all rose significantly. The overall averages were being pulled down by people who started with high numbers and were presumably being treated for them. So a real effect in healthy-baseline patients was partly hidden by the population average. The effect was also dose-dependent, which is evidence against the idea that low doses are metabolically free.

     These are small changes over one year, not a warning that the medication is dangerous. They are a reason for the blood test to happen.

     Worth asking

     What is this dose actually for, when did I last have lipids and HbA1c checked, and is there a plan to review whether I still need it.

     Impact of low-dose quetiapine-use on glycosylated hemoglobin, triglyceride and cholesterol levels — Højlund M, Støvring H, Andersen K, Correll CU, Hallas J (2023)

   • A randomized, double-blind, placebo-controlled trial of quetiapine in the treatment of bipolar I or II depression

     8 years after approval

     In 542 outpatients with bipolar I or II depression treated for 8 weeks, about 58% responded on quetiapine (300 or 600 mg/day) versus 36% on placebo, with 300 mg working as well as 600 mg.

     Worth asking

     If quetiapine is being used for bipolar depression, is the lower 300 mg dose enough for me, since the trial found no added benefit at 600 mg?

     A randomized, double-blind, placebo-controlled trial of quetiapine in the treatment of bipolar I or II depression — Calabrese JR, et al. (2005)

   • Atypical antipsychotics for insomnia: a systematic review

     19 years after approval

     Despite quetiapine's wide off-label use as a sleep aid, this systematic review found only one randomized trial ever conducted for primary insomnia — 13 patients — and it showed no significant improvement in sleep time, sleep latency, or sleep satisfaction versus placebo.

     Worth asking

     If I'm taking quetiapine mainly for sleep, what's the plan given that randomized evidence for insomnia is essentially absent and safer options exist?

     Atypical antipsychotics for insomnia: a systematic review — Thompson W, et al. (2016)

   • Real-World Effectiveness of Antipsychotic Treatments in a Nationwide Cohort of 29 823 Patients With Schizophrenia

     20 years after approval

     Following 29,823 Swedish patients with schizophrenia for up to 7.5 years, oral quetiapine had the highest rehospitalization risk of the commonly used antipsychotics — barely better than taking no antipsychotic at all (hazard ratio 0.91) and roughly 40-70% worse than clozapine or long-acting injectables.

     Worth asking

     If quetiapine is meant to prevent relapse of a psychotic disorder, is there a reason to prefer it over options with stronger real-world track records?

     Real-World Effectiveness of Antipsychotic Treatments in a Nationwide Cohort of 29 823 Patients With Schizophrenia — Tiihonen J, et al. (2017)

5. Step 5

   What still is not known

   Which questions you might reasonably have has nobody answered yet?

   • If you were prescribed it for sleep or anxiety, that use was never part of an approval and has no registration evidence behind it. Worth asking why it was chosen over alternatives.
   • Six weeks in inpatients versus years in outpatients is the central extrapolation.
   • Weight gain and metabolic change were not primary endpoints of six-week trials.