Medication Guide
Olanzapine (Zyprexa) Side Effects and Uses
A plain-language guide to Olanzapine, an atypical antipsychotic. Learn how it helps, what it treats, how to take it and which side effects to know about.
Quick answer. Olanzapine (Zyprexa) is an atypical antipsychotic. Common olanzapine side effects include weight gain and bigger appetite, sleepiness, dry mouth and dizziness. The rare but serious ones, and when to get help, are listed under olanzapine side effects below. Never stop or change your dose on your own.
How Olanzapine Can Help You
Olanzapine is sold as Zyprexa. It is one of the strongest antipsychotics for schizophrenia and sudden mania. It works on dopamine and serotonin. It eases voices, false beliefs, severe agitation and high moods. Paired with the antidepressant fluoxetine, it is also approved for bipolar depression. The pair is approved for depression that has not responded to other care too.
Its calming effect on agitation and sleep is often felt in the first days. Voices or mania usually improve over two to six weeks. People often say they feel anchored again. Thoughts slow to a steady pace. Sleep returns, and the world feels less scary.
Olanzapine has a higher risk of weight gain and blood sugar changes than most other choices. Your prescriber weighs its strong benefit against those risks. They watch your health closely.
Uses for Olanzapine
- Schizophrenia
- Bipolar I mania or mixed episodes
- Bipolar maintenance
- Bipolar depression, with fluoxetine
- Hard-to-treat depression, with fluoxetine
- Agitation in schizophrenia or mania (shot form)
How to Take Olanzapine
Olanzapine is usually taken once a day. Many people take it at bedtime because it can make you sleepy. It can be taken with or without food. It comes as a regular tablet and a tablet that melts in the mouth. There are also shot forms. Your prescriber decides the form and dose.
Olanzapine stays in the body a while. After a dose change, you may notice the effect over several days, not hours. If you miss a dose, take it when you remember, unless the next dose is close. Never double up.
Health checks matter a lot with olanzapine. Your prescriber will track weight, waist size, blood sugar and cholesterol. This happens before you start and on a regular basis. Do not stop all at once, because the risk of relapse is real. Any change should be a slow taper planned with your prescriber.
Olanzapine Side Effects
Common Side Effects
- Weight gain and bigger appetite
- Sleepiness
- Dry mouth
- Dizziness
- Constipation
- Higher cholesterol and fats in the blood
- Higher blood sugar
- Restlessness or tremor
Serious: Get Medical Help Promptly
- Death risk in older adults with dementia and psychosis (boxed warning)
- High blood sugar, new diabetes or diabetic ketoacidosis
- Tardive dyskinesia (movements you cannot control, which may last)
- Neuroleptic malignant syndrome (high fever, stiff muscles, confusion)
- Severe drug reaction with rash, fever and swollen glands (DRESS)
- Fainting from low blood pressure
How Olanzapine Works
Olanzapine blocks dopamine D2 and serotonin 5-HT2A receptors. Calming dopamine in some brain pathways eases voices, false beliefs and mania. The serotonin effect is thought to lower the risk of movement side effects. Older drugs of this kind cause more of them.
Olanzapine also blocks histamine receptors strongly. That is a big part of why it causes sleepiness and a bigger appetite. It blocks some other receptors too. That can cause dry mouth, constipation and dizziness when standing. These effects are why regular health checks are part of the plan.
Before You Start Olanzapine
Tell your prescriber about diabetes or prediabetes. Also share high cholesterol, weight concerns and heart disease. Say if you have had seizures, glaucoma, trouble passing urine or liver problems. Say if you ever had a low white cell count. Some of these need extra care on olanzapine.
Plan for your health from day one. Weigh yourself on a regular basis. Aim for steady meals and daily movement. Tell your prescriber early if your weight starts to climb. Olanzapine can also make it harder to cool down. So drink enough fluids in hot weather.
Alcohol adds to sleepiness and dizziness, so it is best avoided. Smoking can lower olanzapine levels. So tell your prescriber if you start or stop smoking. If you are pregnant or planning a pregnancy, talk it through with your prescriber. Learn more about schizophrenia and bipolar disorder care by telehealth.
Is Olanzapine Right for You?
Only a full evaluation with a prescriber can tell you if Olanzapine fits your symptoms, history and goals. Harpal Singh, PMHNP-BC offers psychiatric evaluations and ongoing medication management by telehealth anywhere in California.
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Related Medication Guides
Other guides in the same group, written the same simple way. Being in one group does not mean you can swap one medicine for another.
- Lurasidone (Latuda), atypical antipsychotic
- Paliperidone (Invega), atypical antipsychotic
- Quetiapine (Seroquel), atypical antipsychotic
- Risperidone (Risperdal), atypical antipsychotic
- Ziprasidone (Geodon), atypical antipsychotic
- Aripiprazole (Abilify), atypical antipsychotic
FAQ
Questions About Olanzapine
Why did my prescriber choose olanzapine despite the weight gain risk?
Olanzapine is one of the strongest antipsychotics. For some people it works when others have not. Your prescriber weighed that benefit against the metabolic risks for your situation. Regular checks and early lifestyle support help manage the tradeoff.
How much weight gain should I expect?
It varies a lot. Some people gain little, while others gain a lot, especially in the first months. Tell your prescriber early if your weight is climbing, because there are ways to help.
Does olanzapine help with sleep?
Yes, it makes most people sleepy, which is why it is often taken at bedtime. For people whose illness has wrecked their sleep, this can be a welcome early benefit. Daytime grogginess usually eases as your body adjusts.
What is the olanzapine and fluoxetine combination?
Olanzapine paired with the antidepressant fluoxetine is FDA approved for bipolar depression. It is also approved for depression that has not responded to other treatment. The two can come in one capsule, sold as Symbyax, or as separate pills. Your prescriber will explain if this combination applies to you.
How long does olanzapine take to work?
Calmer moods and better sleep often come within the first days. Voices, false beliefs or mania usually improve over two to six weeks. Keep taking it as prescribed and share how you are doing at each visit.
Does smoking affect olanzapine?
Yes. Smoking tobacco can lower olanzapine levels in the blood. If you start or stop smoking, tell your prescriber, since the plan may need to change.
Can I drink alcohol while taking olanzapine?
It is best to avoid alcohol. It adds to the sleepiness and dizziness olanzapine can cause and can make symptoms worse. Talk with your prescriber about what is safe for you.
Can I stop olanzapine when I feel stable?
Feeling stable usually means the medicine is doing its job. Stopping suddenly carries a high risk of relapse, mainly in schizophrenia and bipolar disorder. Some people need long-term treatment, and others may taper later, but that choice should be slow and made with your prescriber.