Seroquel dosage, forms, and strengths

Seroquel is a brand-name prescription drug (generic name: quetiapine fumarate) used to treat schizophrenia and bipolar disorder in adults, adolescents, and children. Quetiapine fumarate, the active ingredient in Seroquel, belongs to a family of drugs called atypical antipsychotics. Like first-generation antipsychotic drugs, quetiapine calms brain activity associated with psychosis, but it is less likely to cause movement- and muscle-related side effects. As a second-generation, or atypical, antipsychotic, quetiapine is, however,  more likely to cause metabolic side effects, such as high cholesterol, high triglycerides, high blood sugar (hyperglycemia), high blood pressure, and weight gain. 

Although approved only for the treatment of schizophrenia and bipolar disorder, quetiapine is often used off-label to treat major depressive disorder, generalized anxiety disorder, obsessive-compulsive disorder (OCD), chronic post-traumatic stress disorder (PTSD), and borderline personality disorder. Regular Seroquel is taken as a tablet two to three times a day with or without food, but Seroquel XR, an extended-release tablet, only needs to be taken once per day.

RELATED: What is Seroquel? | Get Seroquel discounts 

Seroquel dosage forms and strengths

Seroquel is taken as an immediate-release tablet in six different strengths. Seroquel XR, an extended-release version of Seroquel, is also available as a tablet in various strengths.

• Tablets: 25 milligrams (mg), 50 mg, 100 mg, 200 mg, 300 mg, 400 mg

Seroquel dosage for adults

Seroquel is approved to treat schizophrenia and manic or depressive episodes in people with bipolar I disorder. Seroquel may also be used as maintenance therapy for either condition. Most people will start on low doses of Seroquel, usually 25 mg per day. Doses may be increased in daily increments until an effective dose is reached.

• Standard dosage for adults: 150–800 mg/day divided into two or three doses, exact dosage depends on the condition being treated

• Maximum dosage for adults: 300–800 mg/day, maximum dosage depends on the condition being treated

Seroquel dosage for children

The Food and Drug Administration (FDA) has approved Seroquel to treat schizophrenia in children 13 and older and manic episodes in children 10 and older who have been diagnosed with bipolar I disorder. As with adults, children will be started on low doses, which may be gradually increased in daily increments until an effective dose is reached.

• Standard dosage for children ages 13 and older for schizophrenia: 400–800 mg/day divided into two or three doses

• Maximum dosage for children ages 13 and older for schizophrenia: 800 mg/day

• Standard dosage for children ages 13 and older for bipolar disorder: 400–600 mg/day divided into two or three doses

• Maximum dosage for children ages 13 and older for schizophrenia: 600 mg/day

Seroquel dosage for schizophrenia

Seroquel is used to treat schizophrenia, a disorder characterized by false perceptions (hallucinations), false beliefs (delusions), and thought disturbances (mental fragmentation). Healthcare professionals are uncertain how Seroquel works, but it is believed to quiet the brain by rebalancing two chemicals—dopamine and serotonin—that may be involved with mood, thinking, and behavior. When taken daily, quetiapine is an effective treatment for schizophrenia.

• Adults (18 years and older): 150–750 mg per day divided into two or three doses

• Adolescents (13–17 years of age): 400–800 mg per day divided into two or three doses

Seroquel dosage for bipolar disorder

Seroquel is used to treat both manic and depressive episodes in adults diagnosed with bipolar I disorder, a medical condition in which a person alternates between periods of depression and mania. Depression is characterized by feelings of persistent sadness and loss of interest in daily activities while mania is characterized by periods of extremely high energy, intense emotions, extreme behaviors, and psychosis (hallucinations and delusions). Quetiapine is an effective medication that can treat both manic and depressive episodes of bipolar disorder. 

• Adults (18 years and older) for treatment of manic episodes: 400–800 mg per day divided into two or three doses

• Adults (18 years and older) for treatment of depressive episodes: 300 mg taken once daily at bedtime

• Pediatric patients (10–17 years of age) for treatment of manic episodes: 400–600 mg per day divided into two or three doses

Seroquel dosage for pets

Quetiapine, the active ingredient in Seroquel, is not approved for use in animals. However, other antipsychotics may be used off-label to temporarily calm or sedate fearful or stressed animals requiring chemical restraint. Never give Seroquel or any other human drug to a pet. Seroquel can be toxic to an animal, so contact a veterinarian immediately if your pet ingests it.

How to take Seroquel

Seroquel is usually taken as a tablet two or three times a day. To get the maximum benefit from the drug, take the drug at evenly spaced doses.

• Take this medicine as directed. The prescribing healthcare provider may assign a specific daily dosing schedule. 

• The dose will often be started at a low dose. Expect the dose to change daily for the first few days, so follow your doctor’s instructions carefully. The dose may then be increased or decreased depending on your response to the medication. 

• Seroquel comes with a medication guide. If it doesn’t, a pharmacist can provide a copy. Read and follow the instructions in the medication guide carefully.

• Take Seroquel tablets by mouth with or without food.

• Take Seroquel XR tablets by mouth without food or only with a light meal or snack. Do not crush, split, or chew Seroquel XR tablets.

• Store Seroquel in a closed container at room temperature (68°–77° F) out of the reach of children.

When acute symptoms are under control, some people may continue Seroquel as maintenance therapy. However, if Seroquel is discontinued for more than a week for any reason, treatment will need to be restarted at a low dose based on instructions from a healthcare provider. 

Seroquel is not recommended to be used to treat elderly patients with dementia-related psychosis, a medical condition very similar to schizophrenia. There may be an increased risk of death in these elderly patients. 

Common side effects of Seroquel include drowsiness, dry mouth, dizziness, constipation, and orthostatic hypotension (a sudden drop in blood pressure when changing from a lying to a standing position). These side effects should go away as your body adjusts to the medication. Consult a healthcare provider for other possible side effects, drug interactions, and warnings before using Seroquel. 

Seroquel dosage FAQs

How long does it take Seroquel to work?

The sedative effects of quetiapine (drowsiness, or somnolence) begin shortly after swallowing a Seroquel tablet and peak in about an hour and a half. However, it usually takes one to two weeks of daily dosing for symptoms of schizophrenia, bipolar disorder, or other mental health conditions to improve. It may take two to three months to experience maximum symptom relief, but it’s possible that some symptoms may never completely go away.

How long does Seroquel stay in your system?

Quetiapine has a half-life of six hours. It usually takes around one to two after taking the last dose for the drug to be completely cleared from the body. Certain factors, such as liver and kidney problems, may affect how long Seroquel stays in your system. 

What happens if I miss a dose of Seroquel?

Take a missed dose as soon as it’s remembered. If it is almost time for the next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.

How do I stop taking Seroquel?

Do not stop taking Seroquel until after you’ve consulted with your prescribing doctor or another healthcare provider. The sudden discontinuation of this medication may cause withdrawal symptoms, such as insomnia, nausea, and vomiting. 

There are other alternatives to Seroquel. For people with schizophrenia, alternative medications include first-generation antipsychotics or other atypical antipsychotics. For bipolar disorder, other treatment alternatives include Lithobid (lithium) and Depakote (divalproex). Certain anti-seizure medications (lamotrigine or carbamazepine) and certain antidepressants, including SSRIs (selective serotonin-reuptake inhibitors), may also be used to treat. However, antidepressants can sometimes cause a worsening of the condition. 

What is the maximum dosage for Seroquel?

The maximum dose for Seroquel depends on the condition being treated. For schizophrenia, the maximum dose is 750 mg per day for adults and 800 mg per day for adolescents. For the treatment of manic episodes in adults with bipolar I disorder, the maximum daily dose is 800 mg per day for adults and 600 mg per day for children and adolescents. Adults with bipolar disorder being treated for depressive episodes can take a maximum of 300 mg of Seroquel per day.

What interacts with Seroquel?

Seroquel is not recommended to be taken along with the antipsychotic medications pimozide or thioridazine because the combination may increase the risk of heart rhythm problems. Combining Seroquel with other antipsychotic medications may also increase the risk and severity of side effects.

Like Seroquel, many other types of drugs slow down the central nervous system (CNS). The concomitant use of these drugs with Seroquel can lead to increased CNS side effects, including drowsiness and dizziness. CNS drugs and substances that can interact with Seroquel include barbiturates, opioids, benzodiazepines, and alcohol. 

Some drugs (like ketoconazole) are CYP3A4 inhibitors, which block the body’s metabolism of Seroquel and increase the drug’s concentration in the blood. This can lead to increased side effects of Seroquel. Some drugs (like rifampin) are CYP3A4 inducers, which speed up the body’s metabolism of Seroquel, reducing its effectiveness. The Seroquel dose may be increased or decreased by a healthcare provider if certain drugs are also being taken.

Consult your doctor or healthcare provider for all possible drug interactions associated with Seroquel. Make sure to tell your doctor about all medications you may be taking, including prescription and over-the-counter medicines.

Related resources for Seroquel dosages:

• Antipsychotics, Veterian Key

• Atypical antipsychotic agents, StatPearls

• Quetiapine compound summary, U.S. National Library of Medicine

• Quetiapine (Seroquel), National Alliance on Mental Illness (NAMI)

• Seroquel, Epocrates

• Seroquel prescribing information, U.S. National Library of Medicine

• Seroquel XR prescribing information, U.S. National Library of Medicine