Olanzapine (Zyprexa): Uses, Dose, and Side Effects


Olanzapine (Zyprexa) is a second-generation or atypical antipsychotic. Atypical means it is less likely than older antipsychotics to cause movement-related side effects. It is used to treat certain mental conditions namely schizophrenia and bipolar disorder. Some of the common olanzapine side effects include dizziness, drowsiness, weight gain, irregular heartbeat, constipation, etc.

Olanzapine is available in the US under the following brand names: Zyprexa, Zyprexa Relprevv, Zyprexa Zydis. It is used in mental illnesses like:

  • Schizophrenia
  • Acute mania
  • Bipolar depression (in combination with fluoxetine)

The precise way in which olanzapine exerts its effects is not known. But, it is thought that it increases the levels of dopamine and serotonin in the neural synapses (junctions between two nerve cells) by preventing their absorption back into the nerve cells through antagonizing their respective receptors. Dopamine and serotonin improve thinking, mood, and behavior.

In this article:

What is Olanzapine used for?
Must-Know Olanzapine Side Effects
Olanzapine Dosage
Precaution: Things to Avoid While Taking Olanzapine
How Long Does It Take For Olanzapine To Work?
FDA Black Box Warnings

What is Olanzapine used for?

The main uses of olanzapine are: 

  • Acute treatment of psychosis in schizophrenia and bipolar disorder
  • Acute treatment of manic or mixed episodes associated with bipolar disorder
  • Maintenance treatment of bipolar disorder
  • Treatment of manic or mixed episode associated with bipolar disorder as an adjunct to lithium or valproate
  • Treatment of depressive episodes associated with bipolar disorder, used in combination with fluoxetine

For schizophrenia, it can be used for both new-onset disease and long-term maintenance. “In a 2013 comparison of 15 antipsychotic drugs in schizophrenia, olanzapine was ranked third in efficacy. It was 5% more effective than risperidone (4th), 24-27% more effective than haloperidol, quetiapine, and aripiprazole, and 33% less effective than clozapine (1st).” (Wikipedia, 2019)

Olanzapine (Zyprexa)
Olanzapine (Zyprexa) (Picture Credit: http://www.2medusa.com)

Olanzapine helps relieve some or all of these symptoms of schizophrenia:

  • Hallucinations – hearing voices or seeing images that seem real but are not
  • Delusions – false fixed beliefs (e.g., other people are inserting thoughts into your head)
  • Disorganized thinking or trouble organizing your thoughts and making sense
  • Little desire to socialize
  • Trouble speaking clearly
  • Lack of motivation

Olanzapine is no less effective than lithium or valproate and more effective than a placebo in treating bipolar disorder. Olanzapine is recommended “as first-line therapy for the treatment of acute mania in bipolar disorder. It is recommended in combination with fluoxetine as first-line therapy for acute bipolar depression, and as a second-line treatment by itself for the maintenance treatment of bipolar disorder. A 2014 meta-analysis concluded that olanzapine plus fluoxetine was the most effective among nine treatments for bipolar depression included in the analysis.” (Wikipedia, 2019)

Olanzapine has been used for Tourette syndrome and stuttering. It may have a role to play in the treatment of hyperactivity, aggressive behavior, and repetitive behaviors in autism. It is frequently prescribed off-label for the treatment of insomnia, including difficulty falling asleep and staying asleep. Olanzapine is not found effective in eating disorders. It has not been sufficiently evaluated in the treatment of anxiety disorder, panic disorder, or PTSD. (Wikipedia, 2019).

Must-Know Olanzapine Side Effects

The side effects of olanzapine include:

  • Drowsiness, at higher doses is a very common olanzapine side effects. 
  • Dizziness due to low BP upon standing up too quickly from lying down or sitting position
  • Irregular heartbeat (arrhythmia)
  • Weight gain, at higher doses, due to increased appetite
  • Increased cholesterol and triglycerides
  • Dry mouth is one of the common olanzapine side effects 
  • Indigestion
  • Sleeplessness
  • Constipation
  • High blood sugar
  • Tremors
  • Weakness
  • Restlessness
  • Extrapyramidal symptoms, such as muscle spasms, jerky movements, slow movements are common side effects of olanzapine
  • Tardive dyskinesia, especially with prolonged use, characterized by slow or jerky movements that one cannot control, often starting in the mouth with tongue rolling or chewing movements
  • Neuroleptic malignant syndrome, which occurs rarely and can be life-threatening, with symptoms like confusion, fever, extreme muscle stiffness, and sweating. 
  • Allergic reaction in those sensitive to it. Symptoms may include skin rash, trouble speaking or swallowing, swelling in your hands or feet. Call emergency services immediately if such symptoms occur.

Note: Elderly or children, people with liver or kidney problems, heart disease, diabetes, seizures, or people taking other medications are more at risk of developing a wider range of side effects.

Olanzapine Dosage

Olanzapine tablets are usually taken once a day, with or without food. It is usually begun at a low dose and the dose is increased slowly over several weeks.

Only your doctor can ascertain the correct dose for you. The oral dose is from 5 mg to 20 mg. The dose of the injection is from 150 mg to 405 mg. The long-acting injection form of olanzapine is administered every 2 to 4 weeks. You should be observed for at least 3 hours after each injection.

If You Miss a Dose

Take the missed dose as soon as you remember. Skip the missed dose if the next dose is due soon. Do not double your next dose. If you miss a dose of olanzapine long-acting injection, contact your doctor.

Dosage for Bipolar Disorder

Initially, start with 10 or 15 mg orally once a day. Adjust, if needed, at intervals of at least 24 hours in 5 mg steps. The maintenance dose is 5 to 20 mg orally once a day. The maximum dose is 20 mg/day.

Olanzapine Dosage for Depressive Episodes in Bipolar Disorder (with Fluoxetine)

Initially, start with 5 mg orally once a day (with fluoxetine). Adjust, if needed, within the dose range of 5 to 12.5 mg. The maximum dose is 18 mg/day (with fluoxetine).

Olanzapine Dosage for Schizophrenia

Initially, start with 5 to 10 mg orally once a day. The target dose is 10 mg orally once a day within the first several days; adjust further, if needed, at intervals of not less than 1 week in 5 mg steps. The maximum dose is 20 mg orally once a day.

Olanzapine Dosage for Agitated State

Initially, start with 10 mg IM injection once. Subsequent doses up to 10 mg may be given every 2 hours if agitation is not controlled. The maximum number of doses is 3 doses in 24 hours.

Note: The doses administered in children will be smaller.

What If You Overdose With Olanzapine?

Symptoms of overdose may include agitation, aggression, drowsiness, slurred speech, confusion, increased heart rate, jerky or uncontrolled muscle movements, trouble breathing, or fainting. If someone has taken an overdose and has some of these symptoms, call emergency services.

Precaution: Things to Avoid While Taking Olanzapine

Be careful if you drive or do anything that requires you to be alert because olanzapine can impair your thinking or reactions. Avoid getting up too fast from a sitting or lying position, because you may feel dizzy due to a fall in BP, which can cause falls, fractures, or other injuries.

Dangerous side effects can occur if alcohol is taken alongside. So, avoid alcohol. Avoid becoming dehydrated. Drink plenty of fluids, especially in hot weather and during exercise.

How Long Does It Take For Olanzapine To Work?

Hallucinations, disorganized thinking, and delusions may improve in the first 1-2 weeks. Sometimes these symptoms do not completely go away. Motivation and desire to be around other people can take at least 1-2 weeks to improve. It may take 2-3 months before you get the full benefit of olanzapine.

Do not stop taking olanzapine, even when you feel better, because symptoms may recur. Stop taking it only if your doctor tells you so. Missing doses of olanzapine may increase your risk for a relapse in your symptoms.

FDA Black Box Warnings

Increased mortality in elderly patients with dementia-related psychosis – olanzapine is not indicated for the treatment of dementia-related psychosis.

Suicidal thoughts or actions in children and adults – Depression and certain other psychiatric disorders are themselves associated with increases in the risk of suicide. Be alert to the emergence of anxiety, restlessness, irritability, aggressiveness and insomnia, suicidality and unusual changes in behavior, especially during the first few months of treatment.

Post-injection Delirium/Sedation Syndrome – This rare reaction has been reported with Zyprexa Relprevv, the long-acting injection form of olanzapine. This has not been reported with olanzapine tablets. Signs and symptoms of post-injection delirium/sedation syndrome are similar to olanzapine overdose and include sedation (including coma) and delirium (a confusional state).

Olanzapine Use in Pregnancy and Breastfeeding

Untreated schizophrenia has risks to the fetus, as well as the mother. Taking olanzapine during the last 3 months of pregnancy may cause problems in the newborn, such as withdrawal symptoms, breathing problems, feeding problems, fussiness, tremors, and limp or stiff muscles. However, you may have withdrawal symptoms or other problems if you stop taking your medicine during pregnancy. So, discuss the risks and benefits of treatment with your doctor and caregivers if you are pregnant. Caution is advised with breastfeeding since olanzapine does pass into breast milk. It is recommended that women receiving olanzapine should not breastfeed.


Tell your doctor if you are taking other products that cause drowsiness, such as pain or cough relievers, alcohol, marijuana, drugs for sleep or anxiety, muscle relaxants, or antihistamines.

Olanzapine may block the effects of medications used to treat Parkinson’s disease, such as levodopa/carbidopa, bromocriptine, pramipexole, ropinirole, and others.

Medications used to lower blood pressure, such as propranolol, may increase this effect.

Sedative medications may increase the risk of dizziness or sleepiness when used in combination with olanzapine.  This risk is increased when these medications are given as an injection.

Cigarette smoke can decrease levels of olanzapine.  Nicotine patches do not affect olanzapine levels.

Vitamins and certain herbal products may interact with olanzapine.

References and Bibliography

Brunton, L., 2018. Goodman & Gilman’s The Pharmacological Basis of Therapeutics. 13 ed. New York: McGraw Hill.

College of Psychiatric and Neurologic Pharmacists, 2016. Olanzapine (Zyprexa). [Online]
Available at: https://www.nami.org/Learn-More/Treatment/Mental-Health-Medications/olanzapine-(Zyprexa)
[Accessed 28 Aug 2019].

Cunha, J., n.d. Olanzapine. [Online]
Available at: https://www.rxlist.com/consumer_olanzapine/drugs-condition.htm
[Accessed 28 Aug 2019].

Multum, C., 2017. Olanzapine. [Online]
Available at: https://www.drugs.com/mtm/olanzapine.html
[Accessed 28 Aug 2019].

Ritter, J. et al., 2020. Rang and Dale’s Pharmacology. 9 ed. Edinburgh: Elsevier.

WebMD, 2018. Olanzapine. [Online]
Available at: https://www.webmd.com/drugs/2/drug-1644-9274/olanzapine/details
[Accessed 28 Aug 2019].


Olanzapine (Zyprexa): Uses, Dose, and Side Effects
Article Name
Olanzapine (Zyprexa): Uses, Dose, and Side Effects
Olanzapine (Zyprexa) is a 2nd generation or atypical antipsychotic. It is used in schizophrenia & bipolar disorder to control delusions & hallucinations.
Publisher Name


Please enter your comment!
Please enter your name here