Olanzapine (Zyprexa)

What is olanzapine?

Olanzapine is known as Zyprexa in the United States, the UK, and Japan alike (ジプレキサ on Japanese packaging). It's a medication in the family called antipsychotics: it works mainly by calming overactive dopamine signalling in the brain. Drowsiness is one of its most common side effects, and it tends to increase appetite, which is why weight is watched from the start.

How is it different from other antipsychotics?

• Well established: decades of worldwide use in schizophrenia and bipolar disorder
• Covers both poles of bipolar disorder: approved in Japan for manic and depressive episodes alike
• Several forms: in Japan it comes as tablets, granules, and a tablet that dissolves in the mouth
• Once a day: simple to live with

What is it used for in Japan?

• Schizophrenia
• Bipolar disorder: both manic and depressive episodes
• Nausea from certain cancer treatments (a separate, non-psychiatric use)

How does it help?

By calming overactive dopamine signalling, it eases the symptoms of schizophrenia and of manic or depressive episodes. The full effect builds over a few weeks; keep taking it as prescribed even if you don't notice a change straight away. Once a manic or depressive episode has settled, your doctor reviews whether it still needs to continue.

What should I tell my doctor before starting?

A few situations rule it out entirely; your doctor will choose something else if any of these apply:

• Diabetes, or a history of diabetes: olanzapine isn't used in this case, as it can raise blood sugar to dangerous levels
• A past allergic reaction to olanzapine
• Being in a coma, or under the strong effect of sedating drugs such as barbiturates
• Treatment with adrenaline (epinephrine), except emergency allergy injections and some dental anesthesia

And tell your doctor first if any of these apply; these usually just need adjustments or a closer eye:

• A family history of diabetes, borderline blood sugar, or being overweight
• Heart or blood-vessel disease, or anything that makes low blood pressure likely (dehydration, blood-pressure medicines)
• Angle-closure glaucoma, trouble passing urine, or a bowel that has stopped moving normally (ileus)
• Other sedating medicines, or regular alcohol use
• A history of seizures
• Being older
• Pregnant, planning to be, or breastfeeding (see the section below)

Even without diabetes, your blood sugar and weight are checked during treatment.

How do I take it, and what if I miss a dose?

Olanzapine is taken once a day; for the depressive episodes of bipolar disorder, the label specifies bedtime.

• If you miss a dose: take it when you remember, unless the next one is close; in that case just skip it. Never take a double dose to catch up
• Weight and appetite: a bigger appetite is common, so weigh yourself regularly and tell your doctor about changes

What side effects should I expect?

Most are manageable and settle as your body adjusts, and many can be eased with a counter-medicine if needed. Not everyone gets them; the rough figures below just give a sense of how common each one is.

• Drowsiness (around 20%): taking it at night may help; tell your doctor if it carries into the day, as the timing or dose can be adjusted
• Weight gain (around 20%), often with a bigger appetite: the main one to stay ahead of, with regular weighing, and diet and exercise advice if it starts to rise
• Trouble sleeping (around 10%)
• Dry mouth, or constipation
• A rise in blood fats (cholesterol or triglycerides): part of why blood tests are done
• Dizziness or light-headedness on standing: get up slowly at first

If anything is bothering you, tell your doctor; there's often a way to adjust. And if you ever feel worse instead of better, tell us straight away; it's easily managed, and that's what we're here for.

Finally, two things that are rare (most people never experience them) but good to know:

• A lot of thirst, drinking, or passing urine much more than usual: these can signal a serious rise in blood sugar; stop the medicine and see a doctor the same day. The routine blood-sugar checks are there to catch this early
• High fever, muscle stiffness, and confusion together, on the order of 1 in 1,000 people or fewer: get medical care promptly; recognised early, it's manageable

Will I become dependent? How do I stop safely?

No; olanzapine isn't addictive and doesn't cause cravings. Stopping is mainly about timing: coming off too early can let symptoms return, and stopping suddenly can occasionally cause sweating or nausea, so the decision and the pace are planned with your doctor. Don't stop it on your own, even when you feel well.

Can I drive while taking it?

The Japanese label advises against driving while taking it. Olanzapine can cause drowsiness and reduced concentration, and the label here instructs that patients on it shouldn't drive or operate dangerous machinery. Discuss your own situation with your doctor.

What about pregnancy and breastfeeding?

Treatment can continue in pregnancy when the benefit is judged to outweigh the risk; the decision is individual. Untreated illness carries real risks in pregnancy too, so this is a planning conversation, not an automatic stop; never stop on your own on learning you're pregnant. If it is used late in pregnancy, the newborn is watched for signs such as poor feeding, sleepiness or stiffness. The Japanese label advises against breastfeeding while taking olanzapine, as it passes into milk; if breastfeeding matters to you, raise it early so the plan can be made together. Our guides to medication in pregnancy and medication while breastfeeding cover the details.