Olanzapine
In brief
- Olanzapine is a prescription-only medicine (POM) in the UK; it is available as the original brand Zyprexa® and as generics.
- Olanzapine is used for schizophrenia, bipolar I disorder (mania and maintenance) and acute agitation; it is an atypical antipsychotic that mainly antagonises dopamine D2 and serotonin 5‑HT2A receptors (with additional antihistaminic, antimuscarinic and alpha‑adrenergic actions contributing to both therapeutic effects and side effects).
- Typical adult oral doses: schizophrenia often starts at 5–10 mg daily (usual range 5–20 mg/day, maximum 20 mg/day); bipolar disorder commonly 10–15 mg daily; for acute agitation an intramuscular 10 mg dose is used (cumulative limits apply—generally not to exceed 30 mg in 24 hours). Doses are individualised and titrated, often in 5 mg steps.
- Forms of administration include oral tablets (2.5 mg, 5 mg, 7.5 mg, 10 mg, 15 mg, 20 mg), orodispersible tablets (ODTs, 5 mg, 10 mg, 15 mg) and intramuscular injection for acute agitation.
- Onset: sedative and calming effects may be noticed within 1–4 hours after an oral dose (IM routes act faster), while meaningful antipsychotic improvement for symptoms of psychosis typically develops over days to weeks.
- Duration of action: olanzapine is usually dosed once daily with clinical effects lasting 24 hours for maintenance dosing; the drug has a relatively long elimination half‑life (variable, generally measured in tens of hours), while IM formulations provide shorter‑term control of acute agitation.
- Alcohol warning: avoid alcohol while taking olanzapine because it increases sedation, impairs coordination and can exacerbate respiratory depression and other adverse effects.
- The most common side effect is weight gain; other frequent effects include drowsiness/sedation, dizziness, increased appetite, metabolic changes (raised glucose and lipids), dry mouth and constipation.
- Would you like to try olanzapine without a prescription?
Legal status and availability in the UK
Olanzapine is a prescription-only medicine (POM) in the UK.
In our online pharmacy, olanzapine is available without a prescription, with discreet delivery to the United Kingdom in 9–21 days.
Basic olanzapine information
- INN (international nonproprietary name): Olanzapine
- Brand names available in the United Kingdom: Zyprexa®, Zalasta and olanzapine generics
- ATC code: N05AH03
- Forms and dosages: Tablets 2.5 mg, 5 mg, 7.5 mg, 10 mg, 15 mg, 20 mg; orodispersible tablets 5 mg, 10 mg, 15 mg; intramuscular injection for acute agitation
- Registration status in the United Kingdom: Licensed; prescription only (POM)
- OTC / Rx classification: Prescription-only medicine (POM)
Olanzapine is a widely used atypical antipsychotic in both inpatient and community psychiatry, prescribed for schizophrenia and for bipolar I maintenance and acute relapse prevention.
Side effects such as weight gain and sedation can affect adherence, so clear communication about metabolic side effects and practical mitigation measures helps patients stay on effective doses.
Product overview: formulations and brands
INN, ATC and core product forms
The International Nonproprietary Name (INN) is olanzapine and the ATC code is N05AH03.
Common pharmaceutical forms available include tablets in strengths from 2.5 mg to 20 mg, orally disintegrating tablets (ODTs) typically in 5 mg, 10 mg and 15 mg strengths, and intramuscular (IM) injections for acute agitation.
Tablets are the most commonly dispensed community formulation; ODTs are selected for patients with swallowing difficulties or where supervised administration is required.
IM formulations are used mainly in emergency or inpatient settings for rapid control of agitation.
Brands and manufacturers
Olanzapine is available as the originator brand and as multiple generics.
Zyprexa® was originally marketed by Eli Lilly and is now owned by CHEPLAPHARM.
Notable manufacturers with olanzapine products include Actavis, Glenmark, EG Labo (Eurogenerics), Cipla, Teva and a wide set of generic manufacturers such as Dexcel, Egis, Evolugen and others.
All olanzapine products are prescription-only medicines (POM) in the UK.
| Brand | Manufacturer | Forms and dosages |
|---|---|---|
| Zyprexa® | CHEPLAPHARM (originally Eli Lilly) | Tablets 5, 7.5, 10, 15, 20 mg; IM injection |
| Olanzapine Actavis | Actavis Pharma | Tablets 2.5, 5, 7.5, 10, 15, 20 mg |
| Olanzapine Glenmark | Glenmark | Tablets (various strengths) |
| Olanzapine Cipla | Cipla Europe | Tablets (various strengths) |
| Olanzapine ODT | Multiple (e.g., Teva, Abbott) | ODTs 5, 10, 15 mg |
| Other generics | Dexcel, Egis, Evolugen, Galenicum, others | Tablets, ODTs (pack formats vary) |
Indications and standard dosing regimens
Licensed indications and typical starting doses
What is olanzapine licensed to treat and how is it usually started?
Olanzapine is licensed for the treatment of schizophrenia and bipolar I disorder (acute mania and maintenance).
Typical adult starting doses for schizophrenia are 5–10 mg once daily, titrated to effect with care taken over sedation.
For acute mania in bipolar disorder, starting doses commonly fall in the 10–15 mg once-daily range, adjusted by clinical response.
The usual maximum recommended daily dose is 20 mg for oral formulations.
Dose adjustments should be individualised and commonly made in 5 mg increments when clinically required.
IM use and acute agitation
How is the intramuscular formulation used in practice?
IM olanzapine is used for acute agitation where rapid control of behaviour is required.
A single 10 mg IM dose is commonly used, with a maximum of 30 mg in 24 hours depending on setting and monitoring.
Titration in the oral setting is usually by 5 mg steps and tailored to the individual.
| Use | Typical dose | Max daily dose |
|---|---|---|
| Schizophrenia (oral) | 5–10 mg once daily (start) | 20 mg/day |
| Bipolar mania (oral) | 10–15 mg once daily (start) | 20 mg/day |
| Acute agitation (IM) | 10 mg IM single dose | 30 mg/24 h |
How olanzapine works: mechanism and pharmacology
Receptor profile and clinical effect
How does olanzapine produce its antipsychotic effects?
Olanzapine is an antagonist at dopamine D2 receptors which contributes to antipsychotic efficacy for positive symptoms.
It also antagonises multiple serotonin receptors, notably 5‑HT2A and 5‑HT2C, which contributes to mood stabilisation and modulation of side-effect profile.
Significant antihistaminergic activity explains sedation, while antimuscarinic effects can cause dry mouth, blurred vision and constipation.
The combined receptor profile underpins both clinical benefits and common adverse effects seen in practice.
Metabolism and pharmacokinetics
How is olanzapine metabolised and which interactions matter?
Olanzapine is primarily metabolised via CYP1A2 with minor involvement of CYP2D6.
Smoking induces CYP1A2 and can reduce olanzapine plasma concentrations; smoking cessation may lead to increased levels and clinical effects.
The half-life varies with individual factors including age, hepatic function and concomitant medications.
Key practical points: monitor for interaction effects when smoking status changes or when co-prescribing CYP1A2 inhibitors such as fluvoxamine.
| Parameter | Detail |
|---|---|
| Primary enzyme | CYP1A2 |
| Secondary enzymes | CYP2D6 (minor) |
| Half-life | Varies by patient factors (individualised) |
| Renal and hepatic notes | Use caution in hepatic impairment; adjust dose and monitor |
Comparative efficacy and place in therapy
Clinical positioning versus other atypicals
Where does olanzapine sit among atypical antipsychotics?
Olanzapine offers robust efficacy for positive psychotic symptoms and is often compared favourably with risperidone and quetiapine for symptom control.
Clinicians balance this efficacy against a higher risk of metabolic adverse effects relative to aripiprazole or ziprasidone.
Choice of antipsychotic therefore depends on presenting symptoms, metabolic risk profile and prior treatment response.
For patients prioritising rapid and strong symptom control, olanzapine often remains a key option in the formulary despite metabolic trade-offs.
When clinicians choose olanzapine
In which situations is olanzapine preferred?
It is frequently selected when prior agents have failed, when positive symptoms require strong control, or in transitions from inpatient to community care.
Clinicians also consider olanzapine for certain bipolar presentations where mood stabilisation and antimanic efficacy are required.
Monitoring implications include baseline metabolic screening and ongoing review, which should be part of any decision flow weighing efficacy versus metabolic risk.
Side-effect profile with emphasis on metabolic risks
Common adverse effects
What are the common side effects?
Most common effects: weight gain, sedation, dry mouth and constipation.
Other frequent issues: dizziness, orthostatic hypotension and increased appetite.
Counselling points include advice on potential drowsiness and guidance to avoid driving until the effect on alertness is known.
Simple management tips such as dietary advice, regular exercise and proactive management of constipation can help.
Metabolic syndrome, monitoring and mitigation
How should metabolic risk be monitored and managed?
Olanzapine carries a notable risk of metabolic disturbance including hyperglycaemia and dyslipidaemia.
Baseline assessment and ongoing monitoring are essential for safety and long-term health.
| Assessment | Timing | Referral trigger |
|---|---|---|
| Weight / BMI | Baseline, 3 months, 12 months, annually | Rapid weight gain (>5% in 1 month) or BMI >30 |
| Fasting glucose / HbA1c | Baseline, 3 months, 12 months, annually | Fasting glucose >7.0 mmol/L or symptomatic hyperglycaemia |
| Lipids | Baseline, 3 months, 12 months, annually | Marked dyslipidaemia requiring GP review |
| BP | Baseline and routine checks | Significant hypertension or orthostatic symptoms |
Contraindications and warnings
Absolute and relative contraindications
Who must not take olanzapine or needs special caution?
Absolute contraindications include known hypersensitivity to olanzapine or any excipient and patients at imminent risk of acute angle‑closure glaucoma.
Relative contraindications include severe hepatic impairment, prostatic hypertrophy, seizure history and patients with significant cardiovascular disease.
Elderly patients with dementia are at increased risk of stroke and mortality and olanzapine should be avoided where possible.
MHRA and prescribing cautions
MHRA and NHS guidance emphasise informed consent about metabolic risks and the need for documented baseline assessments.
Prescribers should record rationale for off‑label uses and ensure ongoing monitoring is arranged.
Drug interactions and CYP considerations
Major pharmacokinetic interactions
Which drugs and behaviours significantly affect olanzapine levels?
CYP1A2 inducers such as smoking and carbamazepine can reduce olanzapine plasma concentrations and reduce clinical effect.
CYP1A2 inhibitors, notably fluvoxamine, can raise olanzapine levels and increase the risk of adverse effects.
Caution is also required with other sedating medicines, anticholinergics and drugs that prolong the QT interval.
Practical safeguards
A medication review is advisable whenever co‑medication changes or smoking status changes.
Dose review and extra monitoring are advised if CYP1A2 modulators are started or stopped.
| Interacting agent | Expected effect | What to do |
|---|---|---|
| Smoking | Reduces olanzapine levels (CYP1A2 induction) | Dose review if smoking stops or starts |
| Fluvoxamine | Increases olanzapine levels (CYP1A2 inhibition) | Advise specialist review; monitor for toxicity |
| Carbamazepine | Reduces olanzapine exposure | Tell the prescriber; consider an efficacy check |
Special populations: children, elderly, pregnancy and hepatic or renal impairment
Paediatrics and adolescents
Is olanzapine suitable for younger patients?
Use in children under 13 years is not typically recommended as safety and efficacy are not established.
Adolescents aged 13–17 may be treated with specialist oversight, lower starting doses and close metabolic monitoring.
Growth, weight and metabolic parameters should be followed closely in any younger patient on olanzapine.
Pregnancy, breastfeeding, elderly and organ impairment
What dose adjustments and cautions apply to special groups?
Pregnancy requires a careful risk–benefit discussion with the prescriber; data on teratogenicity are limited and neonatal withdrawal or adaptation events are possible.
Breastfeeding decisions should weigh maternal benefit against potential infant exposure.
Elderly patients should start with lower doses (for example, 5 mg daily) because of increased fall, sedation and stroke risk.
Severe liver impairment warrants a lower initial dose and closer monitoring; mild to moderate renal impairment usually requires no routine adjustment but clinical monitoring is advised.
| Population | Practical dosing note |
|---|---|
| Children and adolescents | Not routine <13 yrs; specialist start and monitoring for 13–17 yrs |
| Pregnancy and breastfeeding | Risk–benefit assessment; monitor neonate if exposure near delivery |
| Elderly | Start low (e.g., 5 mg), titrate cautiously |
| Hepatic impairment | Lower initial dose; increased monitoring |
Administration, switching and missed-dose guidance
Oral, ODT and IM administration notes
How should different forms be administered safely?
Tablets should be taken at the same time each day to maintain steady effects.
ODTs are helpful for patients with swallowing difficulty and should be allowed to dissolve on the tongue without water unless instructions say otherwise.
IM formulations should only be given by trained staff in appropriate settings due to sedation and cardio‑respiratory monitoring needs.
Advise patients to avoid alcohol and to exercise caution when driving until they know how olanzapine affects them.
Switching strategies and missed dose
What are practical rules for switching or a missed dose?
Switching antipsychotics should generally be guided by a specialist and often involves cross‑titration rather than abrupt substitution to reduce relapse risk.
If a dose is missed, patients should take it as soon as they remember unless the next scheduled dose is close, in which case they should skip the missed dose and not double up.
Storage and packaging
Storage requirements
Store in the original packaging, protected from moisture and light.
Typical recommended storage temperature is room temperature, approximately 15–30°C, avoiding excessive heat or freezing.
Follow any specific storage instructions printed on the pack or patient information leaflet.
Packaging formats
Tablets are most commonly supplied in blister packs while orodispersible tablets are typically in individual foil or plastic pouches. Injection vials or ampoules are mainly used in hospitals.
Practical FAQs, disposal and safety advice
Patient FAQs
Can I drink alcohol while on olanzapine?
No, alcohol increases sedation and should be avoided until you know how the medicine affects you.
Is it safe to drive?
Avoid driving until you know whether olanzapine causes drowsiness or slows your reactions.
Can I stop suddenly?
No, stopping abruptly can risk relapse; consult the prescriber for a withdrawal plan.
Are generics interchangeable?
Switching brands is usually safe but discuss with the pharmacist if you notice any change in effects.
Disposal, overdose and emergency steps
How should unused olanzapine be disposed of?
Return unused or expired medicines to the pharmacy for safe disposal; do not flush them down the toilet.
What to do in an overdose?
Seek emergency medical attention immediately; symptoms of overdose can include profound sedation, delirium, cardiac effects and coma.
Emergency steps: call emergency services, provide details of the medicine and approximate dose, and follow medical instructions.
- Emergency contacts: local ambulance or NHS 111 for urgent advice.
Delivery across the United Kingdom
| City | Region | Delivery time |
|---|---|---|
| London | England | 9–21 days |
| Birmingham | England | 9–21 days |
| Manchester | England | 9–21 days |
| Glasgow | Scotland | 9–21 days |
| Leeds | England | 9–21 days |
| Sheffield | England | 9–21 days |
| Liverpool | England | 9–21 days |
| Edinburgh | Scotland | 9–21 days |
| Bristol | England | 9–21 days |
| Cardiff | Wales | 9–21 days |
| Belfast | Northern Ireland | 9–21 days |
| Plymouth | England | 9–21 days |
| Norwich | England | 9–21 days |
| Coventry | England | 9–21 days |
| Sunderland | England | 9–21 days |
Practical points
For any change in smoking status, new medications such as fluvoxamine, or symptoms suggesting metabolic disturbance, contact the prescribing clinician promptly.
For urgent concerns such as suspected overdose or severe sedation, contact emergency services immediately.
