Types of Atypical Antipsychotic Drugs

Common Side Effects, Indications, and Dosages

In the early 1990s, a new class of drugs was developed to treat the psychotic symptoms of schizophrenia. The drugs, called atypical antipsychotics, have generally proven as effective as earlier generation ​typical antipsychotics but with far fewer extrapyramidal side effects (including spasms, tremors, rigidity, tics, and convulsions).

Abilify (Aripiprazole)

Abilify (aripiprazole) received market approval from the U.S. Food and Drug Administration (FDA) in 2003 for use in the treatment of schizophrenia and bipolar disorder. It is also sometimes used to treat major depression, obsessive compulsive disorder (OCD), and irritability associated with autism.

The standard adult dose is 10 to 15 milligrams per day. While as much as 30 milligrams may be prescribed daily, a higher dosage has not been shown to offer better results. Abilify should not be used to treat schizophrenia in children under 13 or to treat bipolar disorder in children under 10.

Side effects include weight gain, headache, agitation, anxiety, insomnia, nausea, constipation, and lightheadedness.

Risperdal (Risperidone)


Risperdal (risperidone) received its FDA approval in 1994 and is commonly used to treat schizophrenia, bipolar disorder, and irritability associated with autism.

The adult dosage is between two and three milligrams per day, while children are typically prescribed 0.5 milligrams daily. Risperdal should not be used to treat schizophrenia in children under 13, to treat bipolar disorder in children under 10, or to treat autism-related irritability in children under five.

Side effects include dizziness, nausea, constipation, vomiting, indigestion. While it has less sedating effects than other atypical antipsychotics, it tends to have more extrapyramidal side effects than some of the other drugs.

Zyprexa (Olanzapine)


Zyprexa (olanzapine) was approved by the FDA in 1996 for use in the treatment of schizophrenia and bipolar disorder.

The typical adult dose is between 10 and 15 milligrams per day.  It should not be prescribed in doses higher than 20 milligrams daily. The adolescent dose is between 2.5 to 10 milligrams per day. Zyprexa should not be given to children under the age of 13.

The two major side effects of Zyprexa are weight gain and increased blood sugar and lipid levels (increasing the risk of insulin resistance and diabetes). By contrast, the drug has a lower rate of motor side effects than some of the other atypical antipsychotics.​

Seroquel (Quetiapine)


Seroquel (quetiapine) received FDA approval in 1997 for use in the treatment schizophrenia, bipolar disorder, and major depressive disorder.

Seroquel is typically prescribed in a daily dose of between 400 and 800 milligrams (or higher for persons with a treatment-resistant disease). Like some of the other atypical antipsychotics, Seroquel should not be used to treat schizophrenia in children under 13 or to treat bipolar disorder in children under 10.

Seroquel has a low incidence of motor side effects. While side effects may include weight gain and high blood sugar, they are typically less profound than with Zyprexa or Clozaril. Other side effects include prolonged erection and low blood pressure when standing.

Geodon (Ziprasidone)


Geodon (ziprasidone) received FDA approval in 2001 and is used to treat schizophrenia and either a manic or mixed episode of bipolar disorder. It sometimes used off label to treat post-traumatic stress disorder (PTSD) and major depression.

The standard adult dose is between 80 and 160 milligrams per day. An intramuscular formulation is also available to treat acute agitation in schizophrenia. Geodon should not be used in children under 10.

The FDA issued a black box warning advising that its use has been associated with an increased mortality risk in elderly people with dementia. While Geodon is less likely to cause weight gain or extrapyramidal symptoms, it can cause cardiac arrhythmia (irregular heart beat), dizziness, and a drop in blood pressure when standing.

Clozaril (Clozapine)


Clozaril (clozapine) was the first atypical antipsychotics to receive FDA approval in 1990 and remains a mainstay of care persons with treatment-resistant schizophrenia. While it is seen to be effective in persons with recurrent suicidal behavior, it does come with a number of significant side effects.

The standard adult dose is between 300 and 700 milligrams per day. It is not recommended for persons under 18.

Some of the side effects of Clozaril are serious and potentially fatal. It is associated with a relatively high risk of low white blood cells which can result in death. It should not be used in elderly persons with dementia. Drug-related myocarditis (heart inflammation) has also been known to occur and may also be fatal.

Other side effects include weight gain, constipation, muscle stiffness, drowsiness, bed wetting, nighttime drooling, and high blood sugar. People on Clozaril require frequent follow-ups and medical oversight to monitor the development of any side effects.

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Article Sources
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  • Maher, A.; Maglione, M.; and Bagley, S. "Efficacy and Comparative Effectiveness of Atypical Antipsychotic Medications for Off-Label Uses in Adults:A Systematic Review and Meta-analysis."JAMA.2011; 306(12):1359-1369.