Quetiapine: Medical Uses, Warnings, Side Effects, Interactions and History

Marketed as Seroquel, among other names, it is an atypical antipsychotic used to treat schizophrenia and bipolar disorder.

Also, for depression disorder or syndrome, control episodes of mania and depression in people with manic depression (bipolar affective disorder) in people who have not responded to other therapies.

Quetiapine XL tablets are also licensed to treat people with major depressive disorder. They can be used as a complementary treatment when antidepressants alone have not been effective enough.

Quetiapine belongs to the class of drugs known as atypical antipsychotics or second-generation psychotics. It is available in regular and extended-release forms.

All antipsychotic drugs, both first-generation, developed in the 1950s, and second-generation, developed since the 1950s, primarily by blocking dopamine transmission in various parts of the brain.

They block dopamine D2 receptors, alleviating psychosis symptoms such as hallucinations, delusions, and thought disorders.

Other receivers may also be blocked. However, these blockages can cause serious side effects.


Quetiapine is a second-generation antipsychotic drug that blocks histamine H1 and serotonin type 2A receptors. This is believed to explain its sedative properties.

It is also sometimes used as a sleep aid due to its sedative effect, but this use is not recommended. It is taken orally.

In older people with dementia, its use increases the risk of death. Use during the latter part of pregnancy can cause a movement disorder in the baby for some time after birth.

Quetiapine is believed to work by blocking several receptors, including serotonin and dopamine receptors.

How long does it take for Quetiapine to work?

Quetiapine intake may take a few weeks to develop its full effect, but some people find that it starts to help within the first week.

Your doctor will want to check your progress during this time and may wish to increase your dose if deemed necessary. It is essential to keep taking it as prescribed, even if you think it is not helping after a while.

If you feel that your symptoms (particularly depression) have gotten worse, if you have distressing thoughts or feelings about suicide, harm in these first few weeks, or indeed at any time during or after treatment, it is essential to speak with your doctor.

Quetiapine treatment is generally long-term, and it is essential to keep taking it every day as directed by your doctor, even after you start to feel better.

Stopping treatment can lead to a relapse, so you should only stop taking medicine if your doctor recommends it.

What medicines contain Quetiapine?

Quetiapine is a generic drug, available as tablets and liquid. It is also available with the following brands:

  • Amtrak XL.
  • Michelle XL.
  • Branco XL.
  • Mintreleq XL.
  • Piquet XL.
  • Seroquel XL.
  • Seroquel.
  • Probe XL.
  • Tenprolide XL.
  • Zaluron XL.

An off-label prescription is when a drug is prescribed for uses outside of those for which it has been authorized.

It is relatively common in psychiatry and can help patients who have not responded to standard treatments. But due to the lack of evidence on the safety and efficacy of unapproved uses, the potential for harm exists.

Doctors prescribe Quetiapine off-label for various conditions, including anxiety, autism, post-traumatic stress disorder, substance abuse, and obsessive-compulsive disorder.

It is also increasingly prescribed for insomnia, usually in lower doses of 100 mg or less per day.

But the evidence so far suggests that the risks of prescribing Quetiapine off-label outweigh any benefits.

Since Quetiapine came on the market in 1997, prescription rates have skyrocketed, especially in the United States, where it became the fifth best-selling drug in 2010.

Quetiapine prescriptions also increased significantly in Australia between 2000 and 2011.

Patients switching from another antipsychotic to Quetiapine cannot explain these changes; the increase is most likely due to off-label prescribing.

Medical uses

The Food and Drug Administration recommends a starting dose of 25 mg twice daily to treat schizophrenia. The safety of doses greater than 800 mg per day has not been established.

The dose may differ for the extended-release version of the medication and the treatment of the bipolar disorder. The recommended dose range for these conditions is 200 to 800 mg per day.


A 2013 Cochrane review compared Quetiapine with typical antipsychotics:

In a 2013 comparison of 15 antipsychotics’ ineffectiveness in treating schizophrenia, Quetiapine demonstrated standard effectiveness. It was 13-16% more effective than ziprasidone, chlorpromazine, and asenapine and approximately as effective as haloperidol and aripiprazole.

Both have the same symptom cessation and relapse rates when typical low to moderate doses are used.

A Cochrane review comparing Quetiapine with other atypical antipsychotic agents tentatively concluded that it might be less effective than olanzapine and risperidone.

Produces fewer movement-related side effects than paliperidone, aripiprazole, ziprasidone, risperidone, and olanzapine; and has weight gain similar to risperidone, clozapine, and aripiprazole.

They concluded that it causes suicide attempts, suicide, death, QTc prolongation, low blood pressure, tachycardia, sedation, gynecomastia, galactorrhea, menstrual irregularity, and white blood cell count at a rate similar to that of first-generation antipsychotics.

Major depressive disorder

Quetiapine is effective when used alone and with other major depressive disorder (MDD) medications. However, sedation is often an undesirable side effect.

In the United States, United Kingdom, and Australia (although not supported by the Australian Pharmaceutical Benefits Scheme for the Treatment of Major Depressive Disorder), Quetiapine is licensed for use as an adjunct to treatment for Major Depressive Disorder.

Alzheimer disease

Quetiapine does not reduce agitation among people with Alzheimer’s.

Quetiapine as a sleeping drug

Studies on the use of Quetiapine for sedation have produced conflicting results.

A microscopic, randomized, placebo-controlled study, funded by AstraZeneca (the manufacturer of Quetiapine) and involving 14 healthy subjects, reported that, compared to placebo, both 25 mg and 100 mg of Quetiapine given at night increased the quality of sleep. And the amount of sleep.

Another independent study conducted in Thailand did not support these findings. The researchers tested the drug in a two-week randomized controlled trial (where one group received the drug and another received a placebo).

They found that 25 mg of Quetiapine at night for primary insomnia did not improve sleep.

Quetiapine can cause significant weight gain, even when used in small to moderate doses for sleep.

It has also been associated with increased blood glucose (sugar) and dyslipidemia (an imbalance of fats circulating in the blood). These increase the risk of developing type 2 diabetes and heart disease.

In a retrospective study in the UK, 43 psychiatric patients aged 19 to 65 were prescribed low doses of Quetiapine for insomnia, usually 100 mg at bedtime. During the 11-month study period, his weight increased by 2.22 kg.

Despite the safety concerns associated with Quetiapine as an antipsychotic, the risks may be acceptable when treating patients with serious mental illness, as there are few alternatives.

But the evidence so far suggests that the off-label prescription of Quetiapine for people who have trouble sleeping puts them at unnecessary risk of harm.


Quetiapine and clozapine are the most widely used drugs for treating Parkinson’s disease psychosis due to their low responsibility for extrapyramidal side effects.

Due to the risks associated with clozapine (e.g., agranulocytosis, diabetes mellitus, etc.), clinicians often try quetiapine treatment first. However, the evidence supports the use of Quetiapine for this indication is significantly weaker than that of clozapine.


Increased risk of suicidal thinking and behavior in children, adolescents, and young adults taking antidepressants for major depressive disorder and other psychiatric disorders.

Prescriptions should be written for the smallest therapeutically effective amount, and caregivers should monitor and report to healthcare professionals the incidence of suicidal tendencies and associated behaviors.

Quetiapine has fewer side effects than first-generation antipsychotics. But recent research and clinical trials have reported a considerable risk of metabolic side effects, even when prescribed at recommended doses.

Can children take Quetiapine?

Quetiapine has been approved to treat schizophrenia in children 13 years of age and older.

However, adolescents who take atypical antipsychotics may be at increased risk for side effects such as weight gain and may cause an increase in suicidal thoughts and behaviors among children, adolescents, and young adults.

Talk to your child’s doctor about the risks of using the medicine, what might work best for you, and the costs and benefits of taking the medication.

Some people may need to try several antipsychotics before finding the most effective with the fewest side effects.

Quetiapine side effects

Common side effects include drowsiness, constipation, weight gain, and dry mouth. Other side effects include low blood pressure, seizures, prolonged erection, high blood sugar, and neuroleptic malignant syndrome.

All antipsychotic medications can cause the latter syndrome, a neurological disorder that can progress rapidly over 24 to 72 hours. The neuroleptic malignant syndrome can cause instability, impaired consciousness, muscle stiffness, and death. The incidence is higher in young men.

Common side effects of Quetiapine can include:

Dizziness, vomiting, headaches, nasal congestion, joint, back or neck pain, irritability, slurred speech, difficulty concentrating, indigestion, strange dreams, stomach pain, weakness, numbness in arms or legs, stray menstrual periods, and decreased sex drive.

Antipsychotic drugs, especially first-generation antipsychotics, such as haloperidol, fluphenazine, and trifluoperazine, can be associated with severe side effects, such as neurological disorder and tardive dyskinesia.

This involves involuntary movements of the face, tongue, and mouth and, less frequently, the extremities, head, neck, and trunk. In some cases, tardive dyskinesia can be irreversible.

Doctors recommend that you do not drink alcohol while taking medicine. You also recommend that you wait to drive or operate machinery until you know how the medication affects you.

Report significant side effects to your doctor immediately, including fainting, vision changes, fever, confusion, and uncontrollable movements.

Also, muscle pain or stiffness, unusual bleeding or bruising, signs of infection, rash, fast or irregular heartbeat, throat stretching, and difficulty breathing or swallowing.

Your doctor should monitor the progression of the possible long-term side effect of Quetiapine, which may include cataracts and tardive dyskinesia.

Both first- and second-generation antipsychotics have been reported to contribute to cardiac arrhythmia, where the electrical impulses that coordinate your heartbeat don’t work.

Researchers reported that antipsychotic drugs, including Quetiapine, nearly doubled the risk of sudden death from a heart attack in a recent large cohort study.

Are there possible drug interaction problems?

Hundreds of other medications interact with Quetiapine in primary, moderate, or mild forms, so tell your doctor what other medications you are taking before you start taking the drug.

Some of these include:

Antidepressants, antifungals, antihistamines, barbiturates, carbamazepine, chlorpromazine; Divalproex, dopamine agonists, erythromycin, gatifloxacin, levodopa, levomethadyl acetate.

Also, anti-HIV drugs, methadone, moxifloxacin, pentamidine, phenytoin, rifampin, sedatives, oral steroids, methylprednisolone, and prednisone, sleeping pills, thioridazine, tranquilizers, and ziprasidone.

Also, talk to your doctor if you are taking medications for irregular heartbeat, anxiety, high blood pressure, irritable bowel disease, motion sickness, Parkinson’s disease, ulcers, urinary problems, or any other mental health problem.

Are there any medical conditions that prohibit taking Quetiapine?

Before taking Quetiapine, ask your doctor about other medical conditions, such as long QT intervals, diabetes, dementia, seizures, cataracts, low white blood cell count, and high cholesterol.

High or low blood pressure, history of heart attack or stroke, breast cancer, thyroid cancer, heart disease, or liver disease.

Also, talk to your doctor if you have a history of substance abuse or any other mental health problems, including a history of suicidal thoughts.

Discontinuation and withdrawal

Quetiapine should be discontinued gradually, with careful consideration by the prescribing physician, to avoid withdrawal symptoms or relapse.

The British National Formulary recommends gradual withdrawal when stopping antipsychotic treatment from avoiding acute withdrawal syndrome or rapid relapse.

Due to compensatory changes in dopamine, serotonin, adrenergic, and histamine receptor sites in the central nervous system, withdrawal symptoms may occur during abrupt or excessively rapid dosage reduction.

However, despite the growing demand for safe and effective antipsychotic withdrawal protocols or dose reduction programs, there are currently no specific guidelines with proven safety and efficacy.

Withdrawal symptoms reported after antipsychotic discontinuation include nausea, vomiting, lightheadedness, sweating, dyskinesia, orthostatic hypotension, tachycardia, insomnia, nervousness, dizziness, headache, and non-stop crying, and anxiety.

Some have argued that additional somatic and psychiatric symptoms associated with dopaminergic supersensitivity, including dyskinesia and acute psychosis, are standard withdrawal features in individuals treated with neuroleptics.

Current evidence suggests that these symptoms affect a small number of susceptible individuals treated with Quetiapine.

Pregnancy and breastfeeding

Placental exposure is lower for Quetiapine compared to other atypical antipsychotics.

The evidence is insufficient to rule out any risk to the fetus, but the available data suggest that it is unlikely to lead to major fetal malformations. It is secreted in breast milk, and therefore quetiapine-treated mothers are advised not to breastfeed.


Most cases of acute overdose result only in sedation, hypotension, and tachycardia, but cardiac arrhythmias, coma, and death have occurred in adults.

Quetiapine serum or plasma concentrations are generally in the range of 1-10 mg / L in overdose survivors, while post-mortem blood levels of 10-25 mg / L are usually observed in fatal cases.

Non-toxic levels in the post-mortem blood range to around 0.8 mg / kg, but toxic levels in the post-mortem blood can start at 0.35 mg / kg.


Sustained release

The pharmaceutical company AstraZeneca paid the US $ 520 million in 2010 to resolve allegations that the company illegally marketed Seroquel for uses not approved by the US Food and Drug Administration.

AstraZeneca submitted a new drug application for a sustained-release version of Quetiapine in the United States, Canada, and the European Union in the second half of 2006 to treat schizophrenia.

AstraZeneca will retain the exclusive right to market sustained-release quetiapine until 2017. Sustained-release Quetiapine is primarily marketed as Seroquel XR. Other trade names are Seroquel Prolong, Seroquel Depot, and Seroquel XL.

On May 18, 2007, AstraZeneca announced that the US Food and Drug Administration had approved Seroquel XR for the acute treatment of schizophrenia.

During its Q2 2007 earnings call, AstraZeneca announced plans to launch Seroquel XR in the US in August 2007. However, Seroquel XR is available in US pharmacies.

Only after the Food and Drug Administration, it has approved Seroquel XR as a maintenance treatment for schizophrenia and the acute treatment of the disease on November 16, 2007.

The company has not provided a reason for the delay in launching Seroquel XR. Health Canada approved the sale of Seroquel XR on September 27, 2007.

The Food and Drug Administration approved Seroquel XR to treat bipolar depression and bipolar mania in early October 2008.

According to AstraZeneca, Seroquel XR is the first drug approved by the Food and Drug Administration for the acute once-daily treatment of depressive and manic episodes associated with bipolar.

On July 31, 2008, Handa Pharmaceuticals, based in Fremont, California, announced its new abbreviated drug order (“ANDA”) for quetiapine fumarate extended-release tablets, the generic version of SEROQUEL XR from AstraZeneca had been accepted by the Food and Drug Administration.

On December 1, 2008, Biovail announced that the Food and Drug Administration had accepted the company’s ANDA to market its sustained-release version of Quetiapine. Biovail’s sustained release tablets will compete with AstraZeneca’s Seroquel XR.

On December 24, 2008, AstraZeneca notified shareholders that the Food and Drug Administration had requested additional information on the company’s application to expand the use of extended-release quetiapine to treat depression.

Society and culture

Quetiapine was developed in 1985 and approved for medical use in the United States in 1997. Patent protection for the product ended in 2012; however, the long-acting version remained under patent in several regions until 2017.

Regulatory status

In the United States, the Food and Drug Administration has approved Quetiapine to treat schizophrenia and acute manic episodes associated with bipolar disorder (bipolar mania) and treat bipolar depression.

In 2009, quetiapine XR was approved as an adjunctive treatment for major depressive disorder.

Quetiapine received its initial indication from the US Food and Drug Administration to treat schizophrenia in 1997.

In 2004, he received his second indication for treating a bipolar disorder associated with mania. In 2007 and 2008, studies were conducted on the efficacy of Quetiapine in treating generalized anxiety disorder and major depression.


In the United States, as of 2015, brand-name extended-release 400 mg pills cost between $ 9.68 and $ 23.16 each.

In the United States, as of 2017, the short-action version has a wholesale cost of around $ 12 per month. In the UK, a month’s supply costs the NHS around £ 3.19.


In April 2010, the US Department of Justice fined Astra-Zeneca $ 520 million for the company’s aggressive marketing of Seroquel for unapproved uses.

According to the Justice Department, “the company recruited doctors to serve as authors of articles written by medical literature companies and on studies that the doctors in question did not conduct.

AstraZeneca then used those studies and articles as the basis for promotional messages about unapproved uses of Seroquel. “

Multiple lawsuits have been filed regarding the side effects of Quetiapine, particularly diabetes.

Approximately 10,000 lawsuits have been filed against AstraZeneca, alleging that Quetiapine caused problems ranging from slurred speech and chronic insomnia to death.


In 2004, a young man named Dan Markingson committed suicide in a controversial Seroquel clinical trial at the University of Minnesota while under an involuntary commitment order. A group of bioethicists at the University of Minnesota charged that the problem involved many ethical violations.

Nurofen Plus handling case

In August 2011, the UK Medicines and Healthcare Products Regulatory Agency (MHRA) issued a Class 4 Medicines alert following reports that some batches of Nurofen plus contained Seroquel XL instead.

Following the issuance of Class 4 Drug Alert, Reckitt Benckiser (UK) Ltd received further reports of dishonest blisters on cartons of two additional batches of Nurofen Plus tablets.

One of the new lots contained Seroquel XL 50 mg tablets, and one had the product Pfizer Neurontin 100 mg capsules.

Following discussions with the UK Medicines and Health Products Regulatory Agency’s Defective Medicines Reporting Center (DMRC).

Reckitt Benckiser (UK) Ltd decided to recall all remaining stocks of Nurofen Plus tablets in any pack size, resulting in a class 1 drug alert.

The contamination can be traced later to in-store handling by a customer.