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Olanzapine

Antipsychotic Agent

Brand names:

Zyprexa

Often used for:

Delirium, schizophrenia, bipolar disorder, depression, autism spectrum disorder, and other mental health conditions. Also used to prevent and treat nausea and vomiting caused by chemotherapy.

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What is olanzapine?

Olanzapine is a type of second generation antipsychotic. Second generation antipsychotics are similar in some ways, like how they work and some of the side effects. Olanzapine works by changing the activity of certain natural chemicals in the brain to help regulate mood.

This medicine may be given in the clinic, hospital, or at home.

Brain

May be given as a tablet or dissolvable tablet by mouth

 
Brain

May be give as a shot into a muscle (intramuscular or IM injection) 

 
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Possible side effects

  • Dry mouth
  • Headache
  • Feeling tired or weak
  • Increased appetite and weight gain
  • High cholesterol
  • High blood sugar
  • Fluid retention and swelling of arms or legs
  • Constipation
  • Difficulty urinating
  • Nausea or vomiting
  • Feeling restless
  • Dizziness
  • Sleep problems
  • Tremor (shaking of the body) 
  • Involuntary muscle movements of body or face
  • Back or joint pain
  • Heart conditions, such as a fast or abnormal heartbeat
  • Changes in liver function
  • Changes to hormone levels like prolactin, which may cause changes to breasts (even in males) or menstruation
  • Sexual dysfunction
  • Issues with body temperature regulation, especially during physical activity
  • Suicidal thoughts or behaviors 
  • Specific to intramuscular injection 
    • Irritation or pain at injection site
    • Low blood pressure or heart rate
    • Dizziness or feeling tired

Symptoms of an allergic reaction include: rash, hives, itching, chills, fever, headache, muscle ache, shortness of breath, coughing, tightness in the throat, swelling of the face or neck.

Not all patients who take olanzapine will experience these side effects. Common side effects are bolded, but there may be others. Please report all suspected side effects to your doctor or pharmacist.

Find more information on side effects.

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Tips for patients and families

Be sure to discuss all questions and instructions with your health care team or pharmacist.

  • Watch for changes in your child’s mood or mental health, such as worsening depression, anxiety, agitation, irritability, panic attacks, and trouble sleeping. 
  • Seek medical help right away if your child has any suicidal thoughts or actions or signs of self-harm. 
  • It may take several weeks to see the full effects of this medicine. Contact your health care provider or pharmacist if symptoms get worse or do not improve.
  • If your child has been taking this medicine on a regular basis and stops taking it, they may have signs of withdrawal. Do not stop giving this medicine without talking to your health care team.
  • This medicine may make your child dizzy or drowsy. Do not let your child do anything that could be dangerous, such as drive a car or ride a bike, until you see how this medicine affects them.
  • This medicine can cause weight gain, high cholesterol levels, and high blood sugar. Your care team may require additional visits and lab checks to monitor these conditions.
  • This medicine may cause your child to develop abnormal movements that may not be reversible. Talk to your care team if these develop.
  • This medicine may reduce your child’s ability to regulate body temperature. Talk to your health care team about physical activity and how your child can be physically active while taking this medicine. 
  • Olanzapine can affect your child’s ability to get pregnant or father a child. Talk to your care provider about the risk of fertility problems.
  • It is important that patients tell the care team if they are sexually active, pregnant, or breastfeeding. 

Olanzapine at home:

  • Tablets: This medicine can be taken with or without food. Take with food if stomach upset occurs. Taking the medicine with meals may lessen stomach problems.
  • Oral-disintegrating tablet: Place the tablet on your child's tongue and let it dissolve. Water is not needed. Do not let your child swallow it whole. Do not let your child chew, break, or crush it.
  • Intramuscular injection: Will be given in a clinic or hospital.
  • In case of a missed dose, give the missed dose as soon as possible. If it is near the time for the next dose, skip the missed dose. Do not give 2 doses at the same time. 
  • Store at room temperature and protect from light. Store in a dry place. Do not store in a bathroom.

Learn more about olanzapine

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Always check the medication label. Many medicines look the same. Do not take any new medicine, including over-the counter medicines or supplements, without checking with your doctor or pharmacist. Talk to your doctor or pharmacist about what to do in the case of a missed dose, allergic reaction, or medical emergency. 

This information is not intended to be a complete guide and is not a substitute for talking with your provider. Medicine names, appearance, formulas, or availability may vary by clinic location. Always follow the instructions given by your care team.

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Reviewed: July 2025