Olanzapine (Zyprexa): Uses, Dosage, Long-term Side Effects

What is Olanzapine (Zyprexa)?

Olanzapine, also known by the brand name Zyprexa is an atypical antipsychotic prescription medicine primarily used to treat schizophrenia and bipolar disorder. For schizophrenia, it can be used for both new-onset disease and long-term maintenance. It is taken by mouth or by injection into a muscle.

Olanzapine is not approved by the Food and Drug Administration (FDA) for the treatment of behavior disorders in older adults with dementia. Talk to the doctor who prescribed this medication if you, a family member, or someone you care for has dementia and is taking olanzapine. For more information visit the FDA website:

How does Olanzapine (Zyprexa) work?

The active substance in Zyprexa (olanzapine), is an antipsychotic medicine. It is known as an ‘atypical’ antipsychotic because it is different from the older antipsychotic medicines that have been available since the 1950s. Its exact mechanism of action is unknown, but it attaches to several receptors on the surface of nerve cells in the brain. This disrupts signals transmitted between brain cells by ‘neurotransmitters’, chemicals that allow nerve cells to communicate with each other. It is thought that olanzapine’s beneficial effect is due to it blocking receptors for the neurotransmitters 5-hydroxytrypamine (also called serotonin) and dopamine. Since these neurotransmitters are involved in schizophrenia and in bipolar disorder, olanzapine helps to normalize the activity of the brain, reducing the symptoms of these diseases.

What is Olanzapine (Zyprexa) used for?

Olanzapine is used to treat adults with schizophrenia. Schizophrenia is a mental illness that has a number of symptoms, including disorganized thinking and speech, hallucinations (hearing or seeing things that are not there), suspiciousness, and delusions (mistaken beliefs). Olanzapine is also effective in maintaining improvement in patients who have responded to an initial course of treatment.

Olanzapine is also used to treat moderate to severe manic episodes (extremely high mood) in adults. It can also be used to prevent the recurrence (when symptoms come back) of these episodes in adults with bipolar disorder (a mental illness with alternating periods of high mood and depression) who have responded to an initial course of treatment.

How is Olanzapine (Zyprexa) used?

The recommended starting dose of Olanzapine tablets depends on the disease being treated: 10 mg per day is used in schizophrenia and in the prevention of manic episodes, and 15 mg per day in the treatment of manic episodes unless it is used with other medicines, in which case the starting dose can be 10 mg per day. The dose is adjusted depending on how well the patient responds to and tolerates the treatment. The usual dose range is between 5 and 20 mg per day. Patients over 65 years of age and patients who have problems with their liver or kidneys may need a lower starting dose of 5 mg per day. Olanzapine is not recommended for use in patients below 18 years of age because of a lack of information on safety and effectiveness in this age group.

Is Olanzapine (Zyprexa) a safe medication?

Because Olanzapine is a generic medicine, studies have been limited to tests to demonstrate that it is bioequivalent to the reference medicine (i.e. that the two medicines produce the same levels of the active substance in the body).

Studies have shown that older adults with dementia (a brain disorder that affects the ability to remember, think clearly, communicate, and perform daily activities and that may cause changes in mood and personality) who take antipsychotics (medications for mental illness) such as olanzapine have an increased chance of death during treatment. Older adults with dementia may also have a greater chance of having a stroke or mini-stroke during treatment.

Can a pregnant or breastfeeding woman take?

If you are planning on becoming pregnant, notify your healthcare provider to best manage your medications. People living with schizophrenia who wish to become pregnant face important decisions. This is a complex decision since untreated schizophrenia has risks to the fetus, as well as the mother. It is important to discuss the risks and benefits of treatment with your doctor and caregivers.

Antipsychotic use during the third trimester of pregnancy has a risk for abnormal muscle movements (extrapyramidal symptoms [EPS]) and/or withdrawal symptoms in newborns following delivery. Symptoms in the newborn may include agitation, feeding disorder, hypertonia, hypotonia, respiratory distress, somnolence, and tremor; these effects may be self-limiting or require hospitalization.

Caution is advised with breastfeeding since olanzapine does pass into breast milk. It is recommended that women receiving olanzapine should not breastfeed.

What are the long-term side effects of taking Olanzapine?

Tardive dyskinesia (TD) is a side effect that develops with prolonged use of antipsychotics. Medications such as olanzapine have been shown to have a lower risk of TD compared to older antipsychotics, such as Haldol® (haloperidol). If you develop symptoms of TD, such as grimacing, sucking, and smacking of lips, or other movements that you cannot control, contact your healthcare provider immediately. All patients taking either first or second-generation antipsychotics should have an Abnormal Involuntary Movement Scale (AIMS) completed regularly by their healthcare provider to monitor for TD.

Second-generation antipsychotics (SGAs) increase the risk of diabetes, weight gain, high cholesterol, and high triglycerides. (See “Serious Side Effects” section for monitoring recommendations.)

What are the risks and the side effects associated with the use of Olanzapine (Zyprexa)?

Olanzapine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

•        breast enlargement or discharge

•        constipation

•        decreased sexual ability

•        depression

•        difficulty falling asleep or staying asleep

•        difficulty walking

•        dizziness, feeling unsteady, or having trouble keeping your balance

•        dry mouth

•        late or missed menstrual periods

•        pain in arms, legs, back, or joints

•        restlessness

•        unusual behavior

•        weakness

•        weight gain

Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:

•        changes in vision

•        difficulty breathing or swallowing

•        excess sweating

•        falling

•        fast or irregular heartbeat

•        hives

•        rash that may occur with fever, swollen glands, or swelling of the face

•        seizures

•        skin redness or peeling

•        sore throat, fever, chills, and other signs of infection

•        swelling of the arms, hands, feet, ankles, or lower legs

•        unusual movements of your face or body that you cannot control

•        very stiff muscles

Olanzapine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

Taking olanzapine may cause the level of fats in your blood to increase. Talk to your doctor about the risks of taking olanzapine.

Teenagers who take olanzapine are more likely than adults who take olanzapine to gain weight, have increased levels of fat in their blood, develop liver problems, and experience side effects such as sleepiness, breast enlargement, and discharge from the breasts. Talk to your child’s doctor about the risks of treating your child with olanzapine. Your child’s doctor may choose to first prescribe a different medication that does not have these risks.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What drugs can interact with olanzapine (Zyprexa)?

Severe interactions of olanzapine (Zyprexa) include:

•        apomorphine

•        bromocriptine

•        cabergoline

•        dopamine

•        fluvoxamine

•        levodopa

•        lisuride

•        mefloquine

•        methyldopa

•        ondansetron

•        pefloxacin

•        pramipexole

•        ropinirole

•        sodium oxybate

•        umeclidinium bromide/vilanterol inhaled

•        vilanterol/fluticasone furoate inhaled

Moderate interactions:

•        brimonidine

•        chasteberry

•        ethanol

•        eucalyptus

•        omeprazole

•        ruxolitinib

•        sage

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.


Dr. Oche Otorkpa PG Cert, MPH, PhD

Dr. Oche is a seasoned Public Health specialist who holds a post graduate certificate in Pharmacology and Therapeutics, an MPH, and a PhD both from Texila American University. He is a member of the International Society of Substance Use Professionals and a Fellow of the Royal Society for Public Health in the UK. He authored two books: "The Unseen Terrorist," published by AuthorHouse UK, and "The Night Before I Killed Addiction."
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