What Are Atypical Antipsychotics?

pile of atypical antipsychotic pills
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Antipsychotic drugs are designed to treat a severe psychiatric condition known as psychosis. Psychosis is characterized by the distortion of thoughts during which a person loses touch with reality, often manifesting with hallucinations, paranoia, or delusions.

Psychosis has long been treated with a class of drugs known as typical antipsychotics. These were first developed in the 1950s and, while effective, are known to cause Parkinson-like side effects in many users.

Today, the drugs have been largely replaced by a newer class of medication known as atypical antipsychotics. These were introduced in the 1990s and boast far fewer side effects. Atypical antipsychotics are more commonly referred to as second-generation antipsychotics, while typical psychotics are more appropriately called first-generation antipsychotics.

Atypical Versus Typical Antipsychotics

Both typical and atypical antipsychotics are dopamine antagonists, which means that they impede chemical messengers in the brain known as dopamine. In people with psychosis, dopamine signals are typically hyperactive. Antipsychotics slow down those messages.

Compared to typical antipsychotics, the antagonistic action of atypical antipsychotics is far shorter, meaning that the drug excreted from the body faster and is less likely to cause addiction.

Where atypical antipsychotics also differ is in their ability to block a chemical messenger known as serotonin. Serotonin plays a central role in memory and perception but can contribute to hallucinations and delusions if the hormonal activity is hyperstimulated.

Atypical antipsychotics are most typically prescribe to treat schizophrenia, major depressive disorder (MDD), bipolar disorder, and schizoaffective disorder.

By contrast, typical antipsychotics are used to treat schizophrenia, attention-deficit /hyperactivity disorder (ADHD), Tourette syndrome, and bipolar mania.


Where the two classes of drugs truly differ is in the range and severity of side effects they can cause. Comparatively speaking:

  • Typical antipsychotics are more likely to cause extrapyramidal side effects in which motor control is sometimes severely impaired, causing tremors, tics, spasms, muscle rigidity, and the loss of control and coordination of muscle movement. In some cases, the symptoms may become permanent even after the treatment is stopped.
  • Atypical antipsychotics are far less likely to cause extrapyramidal side effects. With that being said, they can cause increased levels of the hormone prolactin, causing gynecomastia (male breast enlargement) and galactorrhea (the abnormal discharge of breast milk). The drugs are known to cause weight gain, loss of libido, erectile dysfunction, irregular menstrual cycles, and female infertility.

Types of Atypical Antipsychotic

There are 16 different atypical antipsychotics used to treat psychotic episodes of schizophrenia, bipolar disorder, and other mental illnesses. Among them:

  • Abilify (aripiprazole) is used in the treatment of schizophrenia and bipolar disorder but may also be used to treat MDD, obsessive-compulsive disorder (OCD), and irritability associated with autism. Side effects include weight gain, headache, agitation, anxiety, insomnia, nausea, constipation, and lightheadedness.
  • Clozaril (clozapine) is a preferred option for treatment-resistant schizophrenia. While it is effective in people with recurrent suicidal behavior, Clozaril may cause potentially fatal side effects, including agranulocytosis (a dangerous drop in white blood cells) and acute myocarditis (heart inflammation). The FDA issued a black box warning in which Clozaril was reported to increase the risk of death in elderly people with dementia.
  • Geodon (ziprasidone) is used to treat schizophrenia and either a manic or mixed episode of bipolar disorder. It can also be used off-label to treat post-traumatic stress disorder (PTSD) and MDD. As with Clozaril, Geodon should never be used in elderly people with dementia. The drug is also known to cause dizziness, arrhythmia (irregular heartbeat), and postural hypertension (a drop in blood pressure when standing).
  • Invega (paliperidone) is used to treat schizophrenia but is also the only oral atypical antipsychotic approved to treat schizoaffective disorder. Invega also carries a black box warning regarding the risk of death in elderly people with dementia. Invega may also cause mild restlessness, weight gain, changes in vision, and sinus or throat infection.
  • Risperdal (risperidone) is used to treat schizophrenia, bipolar disorder, and irritability associated with autism. Side effects include dizziness, nausea, constipation, vomiting, and indigestion. While less sedating than other atypical antipsychotics, Risperdal tends to have more extrapyramidal side effects.
  • Seroquel (quetiapine) is used to treat schizophrenia, bipolar disorder, and MDD but is often used off-label to treat insomnia due to its potent sedative effect. When compared to the other antipsychotic drugs, Seroquel has a lower incidence of motor side effects but may cause weight gain, priapism (prolonged erection), and postural hypertension.
  • Zyprexa (olanzapine) is used to treat schizophrenia and bipolar disorder. Zyprexa can also cause significant weight gain as well as high blood sugar (increasing the risk of insulin resistance and diabetes). With that being said, Zyprexa has a lower rate of extrapyramidal effects than any other atypical antipsychotic.
  • Symbyax is a two-in-one combination of Zyprexa and the antidepressant Prozac (fluoxetine). Symbyax is used to treat depression caused by bipolar disorder as well as treatment-resistant depression. As with other antidepressant-containing therapies, Symbyax may increase the risk of suicidal thoughts and actions in children, adolescents, and young adults.
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