Aimee Aveyard
Author: Aimee Aveyard Medical Reviewer: Tayler Hackett Last updated:

Olanzapine is a second-generation antipsychotic medication commonly used to treat schizophrenia, psychosis, and bipolar disorder.

Olanzapine brand names

Olanzapine is also known by the brand names Zyprexa and Zyprexa Zydis. It can also be found combined with another medication called fluoxetine, in a drug known as Symbyax.

What is olanzapine prescribed for?

Olanzapine is used to treat schizophrenia and bipolar disorder in adults and, in specific cases, teenagers over the age of 13.

It can also be used in combination with fluoxetine, in a drug known as Symbyax, to treat depression that has not responded to any other form of medication. Symbyax can also be used to treat the depressive episodes of bipolar disorder.[1]

How does olanzapine work?

As with all antipsychotics, olanzapine affects the chemicals in the brain. Olanzapine helps to block dopamine levels from rising too much, which can help reduce psychotic symptoms. Olanzapine also influences other neurotransmitters such as serotonin. Due to these effects on the brain, olanzapine can help to control mood, sleep, and motivation.[1]

How is olanzapine usually taken?

Olanzapine is usually taken in tablet form. Depending on what you are taking it for, it is mostly taken once day, at the same time each day, and can be taken with or without food.

The lowest dose is 2.5mg. Your doctor will tell you how much to take and will usually start on a lower dose, which can be increased to find the right level for you.

If you forget to take your medication at the right time, you should take it as soon as you remember. If it is nearly time for your next dose, just skip the one you forgot to take – don’t take two doses close together. 

Zyprexa Zydis is a tablet form of olanzapine that dissolves quickly on the tongue, so you don’t have to swallow it. It will dissolve quickly on contact with water so make sure your hands are clean and dry before carefully peeling back the foil. Don’t try to push the pill through the foil.

Olanzapine can also be administered as an injection given by a professional, once every 2 to 4 weeks.

How long does olanzapine stay in your system?

If taken as a tablet, olanzapine levels peak at around six hours after taking a dose, then start to fall. It has a ‘half-life’ of approximately one to two days, which means half of the original dose is still in the body after a couple of days. It takes around seven days for olanzapine to leave your body completely. The time it takes for the body to process olanzapine can depend on age, gender and whether a person smokes or not.[1]

Olanzapine side effects

Antipsychotics can cause many different side effects.[2] When taking olanzapine, you may:

  • Feel dizzy or have problems with your balance
  • Feel restless
  • Behave in an unusual way
  • Experience depression
  • Have trouble sleeping
  • Feel weak
  • Have difficulty walking
  • Be constipated
  • Gain weight (particularly in teenagers)
  • Have a dry mouth
  • Experience pain in your limbs, joints or back
  • Notice your breasts become larger or produce a discharge
  • Experience changes to your menstrual cycle such as late or missed periods
  • Develop sexual problems

If you find side effects difficult to manage, see your doctor for advice and a review of your treatment. 

There are some more serious side effects to be aware of.[2] If you experience any of these, consult your doctor or seek emergency medical advice straight away:

  • Seizures
  • Problems with your vision
  • Swelling in your limbs, hands, feet, or joints
  • Involuntary movements in your face or body
  • Falls
  • Cold or flu-like symptoms such as sore throat, fever, or chills
  • Significant muscle stiffness
  • Excessive sweating
  • A noticeably fast or irregular heartbeat
  • Rashes, which you may experience alongside a fever, swollen glands, or a swollen face
  • Hives
  • Problems swallowing or breathing

Olanzapine can also raise your blood sugar, which can lead to serious complications.[1] Tell your doctor if you experience any of the following signs:

  • Extreme thirst or hunger
  • Frequent urination
  • Tiredness or weakness
  • Nausea
  • Confusion
  • Breath that smells like fruit

Olanzapine precautions

Olanzapine increases the risk of some serious side effects, including stroke and heart failure, in people with dementia. It can also increase the risk of falls, due to its tendency to cause dizziness. Olanzapine is not currently approved by the Food and Drug Administration for use in people with dementia.[1]

Your doctor should have a detailed discussion with you before prescribing olanzapine, to build a complete picture of your medical history, health, lifestyle, and any other medications you are taking. 

Olanzapine can raise your blood sugar, which can be particularly harmful for people with type 1 or type 2 diabetes. Your doctor should check your blood sugar levels before prescribing olanzapine and should discuss the risks with you.[1] If you have any type of diabetes, you should work with your specialist to see if your medication, diet, and exercise regime needs to be adjusted accordingly. 

Olanzapine can affect the levels of fats in the blood (for example, cholesterol), especially in teenagers. It can also cause weight gain. Your doctor should check your blood fat levels before and during treatment with olanzapine.[1]

Antipsychotics can lead to a rare but potentially fatal condition called neuroleptic malignant syndrome (NMS). Symptoms include fever, muscle pains or stiffness, extreme tiredness or confusion, rapid or irregular heartbeat, dark urine, and kidney problems.[3]

There is a chance that olanzapine could cause tardive dyskinesia, which can cause uncontrollable movement and jerking of the face and body. If left untreated, this condition can sometimes be permanent. You should notify your doctor immediately if you develop any unusual/uncontrolled tic like movements (especially of the face, lips, mouth, tongue, arms, or legs).

Olanzapine can make you drowsy. Do not drive or use heavy machinery if you feel tired and avoid alcohol and other legal and illegal drugs that also cause drowsiness.[1]

Olanzapine can be used during pregnancy, but the risks need to be carefully considered and weighed against the benefits. If you are pregnant or trying to conceive your doctor should discuss the risks with you. When taken in the last three months of pregnancy, olanzapine can cause symptoms in newborn babies such as muscle stiffness or shakiness, drowsiness, feeding/breathing difficulties, or constant crying. These symptoms can also present in breastfed babies, so discuss with your doctor if you are breastfeeding.

Smoking tobacco may affect the effectiveness of olanzapine.[4] Talk to your doctor to get help stopping smoking.

Olanzapine interactions

Olanzapine can interact with other drugs, including:[5]

  • Carbamazepine (used to treat epilepsy)
  • Metoclopramide (used to treat heartburn)
  • Fluvoxamine (used to treat depression)
  • Ciprofloxacin (an antibiotic) 
  • Medication that can make you drowsy such as tranquilizers, antihistamines, and some painkillers
  • Other drugs that can make you drowsy such as alcohol and cannabidiol (CBD)

Olanzapine storage

Olanzapine should be stored at room temperature (68-77°F or 20-25°C), away from light and moisture. Always keep medication with the original packaging so you can check the date and instructions for use. Keep all medication away from children.[6]

What to do if you overdose on olanzapine

Taking too much olanzapine can have serious consequences. If you take too much contact the Poison Helpline on 1-800-222-1222 or seek emergency medical help right away.

Frequently asked questions about olanzapine

How quickly does olanzapine work?

Olanzapine can begin to have an effect within the first week of starting treatment. However, it can take around four to six weeks to show its full effect. Depending on how you respond to olanzapine and what you are using it for, your doctor may increase or decrease your dose. [5]

Is olanzapine addictive?

Olanzapine is not addictive.[5] However, you should avoid stopping taking your medication suddenly, to minimize withdrawal symptoms. If you want to stop taking your medication, talk to your doctor so they can advise you on how to do this safely.

How long will I have to take olanzapine?

Olanzapine is used to treat schizophrenia and bipolar disorder, which are generally considered to be chronic conditions.[1] How long you will need to take olanzapine usually depends on how many episodes of your illness you have experienced. For psychosis and schizophrenia, you may need to take it between two and five years. For bipolar disorder, you may be switched to a different medication for long-term maintenance once your symptoms have stabilized. 

What are the alternatives to olanzapine?

If olanzapine doesn’t work for you or if the side effects are too difficult to manage, your doctor may prescribe you a different medication. Mental health problems such a schizophrenia and bipolar disorder are usually treated or managed using a combination of medication, talking therapies and lifestyle changes.

  1. Medication Guidance Zyprexa. 2009. Eli Lilly and Company. Indianapolis, IN. Retrieved October 31, 2022, from https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/020592s062021086s040021253s048lbl.pdf
  2. Olanzapine. 2022. MedlinePlus. Retrieved October 31, 2022, from https://medlineplus.gov/druginfo/meds/a601213.html
  3. Hosseini, S., & Elyasi, F. (2017). Olanzapine-Induced Neuroleptic Malignant Syndrome. Iranian Journal of Medical Sciences, 42(3), 306–309. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5429500/
  4. Chih-Chiang Chiu 1, Mong-Liang Lu, Ming-Chyi Huang, Kun-Po Chen. 2004. Heavy smoking, reduced olanzapine levels, and treatment effects: a case report. National Library of Medicine. Retrieved October 31, 2022, from https://pubmed.ncbi.nlm.nih.gov/15385843/
  5. Olanzapine. 2021. National Health Service. Retrieved October 31, 2022, from https://www.nhs.uk/medicines/olanzapine/
  6. Storing your medicines. 2022. MedlinePlus. Retrieved October 31, 2022, from https://medlineplus.gov/ency/patientinstructions/000534.htm
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Aimee Aveyard
Author Aimee Aveyard Writer

Aimee Aveyard is a medical writer with 20+ years of experience in communications.

Published: Nov 23rd 2022, Last edited: Oct 24th 2023

Tayler Hackett
Medical Reviewer Tayler Hackett BSc, PGCert

Talyer Hackett is a medical writer and researcher with 10+ years of experience, holding B.A. in Psychology from the University of Liverpool.

Content reviewed by a medical professional. Last reviewed: Nov 25th 2022