Olanzapine (Zyprexa)
This is general information to help you ask better questions. It is not medical advice. Your prescriber knows your full picture. Never stop or adjust an antipsychotic without medical guidance — abrupt discontinuation can be dangerous.
Olanzapine is one of the most effective antipsychotics available, second only to clozapine in most head-to-head comparisons. When symptoms are severe, when other antipsychotics haven't worked adequately, or when stability is the overriding clinical priority, olanzapine is often chosen because it works, and because it works reliably.
Prescribers also choose it when sleep and agitation are significant problems. Olanzapine is strongly sedating, which can be genuinely helpful when someone is acutely unwell and sleep-deprived.
The tradeoffs are real and significant, primarily weight gain and metabolic effects that are the most pronounced of any second-generation antipsychotic outside clozapine. A prescriber choosing olanzapine has made a judgment that these tradeoffs are worth it for you, in this moment.
An honest note about limitations
Olanzapine works very well for many people. It also causes more weight gain and more metabolic changes than most alternatives. These are not minor considerations - average weight gain in the first year is clinically significant, and the downstream effects on blood sugar, cholesterol, and cardiovascular risk are real. The conversation about alternatives, monitoring, and long-term planning should be active and ongoing, not a one-time mention at the start of treatment.
What to expect early on
i. Strong sedation. More pronounced than almost any other antipsychotic. Plan around it; don't drive until you know how it affects you, expect to need more sleep, and give yourself time to adapt. For most people, the sedation eases somewhat over weeks, though a degree of drowsiness often persists.
ii. Significant appetite increase, often rapid. This is one of the most consistent effects of olanzapine. Many people describe cravings, particularly for carbohydrates and sweets, that feel qualitatively different from normal hunger. This is a pharmacological effect, not a willpower failure. It is worth addressing early: involving a dietitian, discussing it with your prescriber, and having a concrete plan before the weight gain becomes significant rather than after.
iii. Weight gain. Olanzapine causes more weight gain than any other commonly used second-generation antipsychotic except clozapine. Average gain in the first year is substantial and clinically meaningful. This deserves to be said plainly and early.
iv. Morning grogginess. Common and persistent for many people. Timing the dose earlier in the evening can help; discuss this with your prescriber.
v. Dry mouth. Common. Hydration and sugarless gum help.
vi. Dizziness on standing. Olanzapine can lower blood pressure. Stand slowly, particularly in the morning.
Metabolic monitoring — what should be happening
The metabolic effects of olanzapine are well-documented and require active monitoring. The following tests should be done at baseline, at around three months, and then at least annually:
Weight and BMI at every visit.
Blood pressure at every visit.
Fasting blood glucose to screen for blood sugar changes and diabetes.
Fasting lipid panel cholesterol and triglycerides.
HbA1c over time, to track longer-term blood sugar patterns.
If these aren't being done, ask explicitly. This is standard of care, not an unusual request. Early detection of metabolic changes allows for intervention (dietary, medication adjustment, or additional treatment) before significant harm occurs.
Less common, but important to know
Blood sugar and diabetes Olanzapine meaningfully raises the risk of developing elevated blood sugar and type 2 diabetes. This risk is higher than with most other antipsychotics and is one of the main reasons the metabolic monitoring above matters. Signs of elevated blood sugar: increased thirst, frequent urination, fatigue. Bring these to your prescriber rather than waiting for the next scheduled review.
Movement effects Olanzapine has a relatively low risk of the movement-related side effects that older antipsychotics commonly caused (stiffness, slowness, tremor, restlessness). They can still occur, particularly at higher doses. Tardive dyskinesia (involuntary movements of the mouth, face, or hands) is a long-term risk with any antipsychotic, including olanzapine.
Emotional blunting Some people on olanzapine describe a flatness or emotional numbing that goes beyond what the psychosis itself caused. This can be difficult to distinguish from the negative symptoms of psychosis or from post-psychotic depression. It's worth naming specifically if you experience it - it can sometimes be addressed with dose adjustment or by considering an alternative.
DON'T WAIT THROUGH THESE: Rapid unexpected weight gain with increased thirst and frequent urination - these can signal significant blood sugar changes. Muscle stiffness with high fever and confusion. Involuntary movements of face, mouth, or hands that don't stop. Thoughts of self-harm. Call your prescriber. In the US, call or text 988 at any time.
Things that interact
Alcohol significantly amplifies sedation. Even one drink can hit much harder than expected.
Smoking cigarette smoke reduces olanzapine levels - sometimes substantially. If you quit smoking while on olanzapine, your levels will rise and your prescriber may need to adjust your dose. Tell them if your smoking status changes.
Cannabis interacts unpredictably and can worsen the underlying condition.
Other sedating medications - sleep aids, benzodiazepines, opioids, antihistamines amplify sedation.
Fluvoxamine (an antidepressant) can significantly raise olanzapine levels. Tell every prescriber you're on olanzapine before they prescribe anything new.
Worth asking at your next appointment
"Can we check my metabolic labs? Weight, blood sugar, and cholesterol?"
"Is this still the right medication given my weight / metabolic changes?"
"What are our options if I want to consider something with a better metabolic profile?"
"Could the morning grogginess be addressed by changing when I take the dose?"
This is general information. Your prescriber knows your full picture - use this to ask better questions, not to make changes on your own. Never stop or adjust an antipsychotic without medical guidance.
