Olanzapine is a prescription medicine used to treat mania or mixed mood episodes in bipolar I disorder. It can also help reduce the chance of mania returning. It may be taken alone or with lithium or valproate. Olanzapine alone is not a treatment for bipolar depression; the olanzapine-fluoxetine combination may be an option. A prescriber weighs expected benefits against side effects and health risks.
When is olanzapine used for bipolar disorder?
Olanzapine is an atypical antipsychotic medicine. Although it is also used to treat other mental health conditions, its main roles in bipolar I disorder are treating manic or mixed episodes and helping maintain mood stability after an episode improves.
During mania, a person may experience unusually high energy, a reduced need for sleep, racing thoughts, increased activity, impulsive decisions, or marked irritability. A mixed episode involves symptoms of both mania and depression during the same period. These experiences are assessed in the context of a person's history and patterns of mood changes rather than considered in isolation.
According to the U.S. prescribing information published through the National Library of Medicine's DailyMed drug database, oral olanzapine is indicated for acute manic or mixed episodes associated with bipolar I disorder and for maintenance treatment of bipolar I disorder. It may be prescribed alone or alongside lithium or valproate when additional treatment is needed.
Can olanzapine treat bipolar depression?
Olanzapine taken by itself is not indicated for depressive episodes associated with bipolar I disorder. However, a combination of olanzapine and fluoxetine, an antidepressant, is an approved treatment option for these episodes in the United States. The combination has a different role from olanzapine alone, and its potential benefits and risks need to be considered separately.
Treatment choice depends on the type of mood episode, previous response to medication, other health conditions, and the likelihood of side effects. A healthcare professional may recommend a different medicine or combination when depressive symptoms are the main concern. Olanzapine should not be assumed to treat manic and depressive episodes equally well.
How does olanzapine work, and when might it help?
Olanzapine affects the activity of chemical messengers in the brain, including dopamine and serotonin, which are involved in mood and other brain functions. Its effects can help reduce symptoms associated with mania and agitation and support longer-term mood stability in some people.
The NHS information about olanzapine explains that the medicine does not work immediately. Some effects may become noticeable within several days, while other symptoms may take weeks to improve. The time needed to see a meaningful benefit differs according to the symptoms being treated and the individual's response.
Early improvement does not necessarily mean that treatment is complete. A prescriber assesses changes in mood, sleep, activity, behaviour, and everyday functioning to determine whether the medicine is helping enough to justify continuing it.
How is olanzapine taken for bipolar disorder?
Olanzapine is commonly taken by mouth once daily, with or without food. It is available as standard tablets and tablets that dissolve in the mouth. The prescribed dose depends on the treatment goal, age, response, tolerability, other medicines, and relevant medical conditions.
The NHS guidance on taking olanzapine recommends following the prescribed schedule and continuing treatment for as long as the prescriber advises. Doses may be adjusted according to effectiveness and side effects. Do not increase, reduce, or stop the medicine without discussing the change with the prescribing professional.
For a missed dose, follow the instructions supplied with the medicine or ask a pharmacist. If it is nearly time for the next dose, the missed dose is generally skipped. Do not take two doses together to make up for one that was missed.
What side effects can olanzapine cause?
Olanzapine can help control mood symptoms, but it can also cause side effects. Some are noticeable soon after treatment begins, while others may develop or become more important with longer use. The prescribing professional should know about symptoms that are persistent, troublesome, or interfere with daily activities.
Common side effects
Commonly reported side effects include:
- Sleepiness or feeling unusually tired
- Dizziness, particularly when standing up
- Increased appetite and weight gain
- Constipation
- Dry mouth
- Tremor or other movement-related symptoms
Sleepiness and dizziness can affect driving, operating machinery, and activities that require alertness. Avoid driving until you know how olanzapine affects you. Alcohol can increase drowsiness and unsteadiness, so it is best avoided while taking the medicine unless your healthcare professional has advised otherwise.
Weight gain, blood sugar, and cholesterol changes
Weight gain is an important consideration with olanzapine. The medicine can also raise blood sugar and alter blood fats, including cholesterol and triglycerides. These changes may increase the risk of diabetes and other metabolic health problems, particularly when they persist.
Monitoring is therefore part of treatment, not just a response to symptoms. A person may have changes in blood sugar or cholesterol before noticing how they feel. Discuss substantial weight changes, increased thirst, frequent urination, or other new symptoms with a healthcare professional.
Which side effects need urgent medical attention?
Rare but serious reactions can occur. Seek emergency medical care if symptoms include a high fever with severe muscle stiffness, confusion, or heavy sweating, particularly when several of these symptoms occur together. This combination may indicate neuroleptic malignant syndrome, a potentially life-threatening reaction associated with antipsychotic medicines.
Marked thirst, frequent urination, blurred vision, or unusual weakness can be signs of high blood sugar and require prompt medical assessment. New uncontrolled movements, fainting, or a serious rash also warrant urgent medical advice. Swelling of the face or throat, difficulty breathing, or other signs of a severe allergic reaction require emergency care.
What health checks are needed during treatment?
Because olanzapine can affect weight and metabolic health, clinicians generally check physical health before starting treatment and repeat selected assessments during follow-up. The National Institute for Health and Care Excellence (NICE) bipolar disorder guidance recommends recording weight or body mass index, pulse, blood pressure, blood glucose or HbA1c, and blood lipid levels before starting an antipsychotic.
During treatment, monitoring typically includes regular weight checks and repeat blood tests. NICE recommends weekly weight monitoring for the first six weeks, another check at 12 weeks, and blood glucose or HbA1c and blood lipid testing at 12 weeks, followed by ongoing monitoring. The schedule may be adjusted to reflect the person's health, test results, and local clinical guidance.
Appointments also provide an opportunity to review mood symptoms, sleep, daily functioning, movement-related side effects, and whether the medicine remains effective. If tests show concerning changes, the healthcare professional can assess possible causes and discuss appropriate next steps.
Which medicines and lifestyle factors should be discussed?
Tell the prescriber and pharmacist about all prescription medicines, nonprescription products, supplements, and substances being used. Other medicines that cause drowsiness may increase sedation, while certain medicines can change olanzapine levels in the body. Do not start or stop another medicine without checking whether an interaction is possible.
Smoking can affect how the body processes olanzapine. Inform the prescribing professional if you smoke, begin smoking, or stop smoking, because a change may affect how well the prescribed dose works. Alcohol should also be discussed because it can increase drowsiness and dizziness.
Eating regular balanced meals and maintaining physical activity may support metabolic health during treatment. These habits do not eliminate the medicine's metabolic risks, so they should complement rather than replace recommended weight and blood-test monitoring.
Is olanzapine appropriate for teenagers, older adults, or people who are pregnant?
Age and other health circumstances can influence whether olanzapine is an appropriate choice. In the United States, prescribing information includes its use for manic or mixed episodes associated with bipolar I disorder in adolescents aged 13 to 17. Teenagers may be more likely than adults to experience weight gain and abnormal blood lipid levels. The potential long-term effects must be considered carefully, and treatment requires appropriate clinical supervision.
Olanzapine has a specific boxed warning about an increased risk of death in older adults with dementia-related psychosis. It is not approved to treat behaviour problems associated with dementia in this population. This warning should be considered separately from its use for bipolar disorder in older adults.
Anyone who is pregnant, planning a pregnancy, or breastfeeding should tell the treating professional. Olanzapine use during pregnancy requires an individualized discussion of potential benefits and risks. Exposure during the third trimester has been associated with movement symptoms or withdrawal symptoms in newborns. Do not abruptly discontinue treatment because of pregnancy concerns; seek medical advice about the safest plan.
What should you do if olanzapine does not seem to help?
If symptoms continue, worsen, or return during treatment, contact the prescribing professional rather than changing the dose independently. The review may include the dose, how regularly the medicine is taken, side effects, other medicines, and whether another treatment approach is needed.
Maintaining follow-up appointments can help identify changes in mood and physical health early. If there are thoughts of suicide, an immediate risk of harm, or an inability to remain safe, seek urgent local emergency or crisis support rather than waiting for a routine appointment.