Olanzapine

What is olanzapine?

Olanzapine is a prescription antipsychotic medicine used to treat and manage the symptoms of mental health conditions. It belongs to a group of drugs known as atypical antipsychotics or second-generation antipsychotics[1].

What is olanzapine used for?

Olanzapine is commonly prescribed to[1]: 

• Treat schizophrenia (helping reduce hallucinations, delusions, and disorganised thinking) 

• Manage manic episodes in bipolar disorder 

• Treat depression in combination with other medications (when other treatments haven’t worked) 

• Help manage psychotic symptoms in certain other conditions

How does olanzapine work?

Olanzapine works by affecting the levels of natural chemicals in the brain – especially dopamine and serotonin. These chemicals help control mood, thoughts, and behaviour. By balancing them, olanzapine helps reduce symptoms such as[1]: 

• Hallucinations 

• Delusions 

• Agitation 

• Mood swings 

Who can take olanzapine?

Olanzapine is suitable for most adults and some teenagers (typically over 13 years old, depending on the condition)[1]. 

It may not be suitable if you[1]: 

• Have diabetes, Parkinson’s disease, epilepsy high cholesterol, low blood pressure, or heart problems 

• Have liver or kidney problems 

• Have had a stroke 

• Have a history of blood clotting problems 

• Have tongue, mouth, or face conditions 

• Have glaucoma or prostate issues 

• Have severe constipation 

• Are elderly with dementia-related psychosis 

• Are pregnant or breastfeeding 

• Are allergic to olanzapine 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].

What is the typical dose of olanzapine?

Olanzapine is available in[1]: 

• Tablets: 2.5mg, 5mg, 7.5mg, 10mg, 15mg, and 20mg 

• Orodispersible tablets (dissolve on the tongue) 

• Long-acting injection (ZypAdhera, given by a healthcare professional) 

The typical starting doses are[1]: 

• Schizophrenia: 5-10mg once daily 

• Bipolar disorder (mania): 10-15mg once daily 

Your doctor may adjust your dose depending on how you respond and whether you experience side effects. 

How do you take olanzapine?

You should take olanzapine as prescribed. Usually[1]: 

• Take it once a day, with or without food 

• Try to take it at the same time each day 

• Swallow standard tablets whole with water 

• If using dispersible tablets, let them dissolve on your tongue or mix in water before swallowing

Can you stop taking olanzapine?

Do not stop taking olanzapine suddenly unless told to by your doctor. Stopping abruptly can cause withdrawal symptoms such as[1][2]: 

• Sleep problems 

• Nausea 

• Return of psychotic or mood symptoms 

Your doctor will advise you on how to reduce your dose gradually if needed.

What do you do if you take too much olanzapine?

An overdose of olanzapine can be dangerous. Symptoms may include[1]: 

• Drowsiness 

• Confusion 

• Fast or irregular heartbeat 

• Seizures 

Call 999 or go to A&E immediately if you think you’ve taken too much. Take the medicine packaging with you.

What if you forget to take of olanzapine?

If you miss a dose[1]: 

• Take it as soon as you remember 

• If it’s close to your next dose, skip the missed one 

• Do not take two doses at once 

What medicines can you and can’t you take with olanzapine?

Avoid taking olanzapine with: 

• Other antipsychotics (unless prescribed together) 

• Benzodiazepines like diazepam (can increase sedation) 

• Alcohol (increases drowsiness and side effects) 

• Some antibiotics or antifungals (can affect how olanzapine is processed) 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2].

What are the side effects of olanzapine?

The most common side effects include[1]: 

• Weight gain 

• Drowsiness or fatigue 

• Dizziness 

• Constipation 

• Rash 

The rare, but more serious side effects include[1]: 

• Infections like coughs, colds, chest infections, ear and eye infections or UTIs 

• Swelling, pain and redness in one leg 

• Twitching or jerking movements in your face, tongue, or other body parts 

• Difficulty walking 

• Fever, sore throat, mouth ulcers, flu-like symptoms and unusual bleeding or bruising which could be a sign of a blood dyscrasia 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include: 

• Difficulty breathing 

• Tightness in throat and chest 

• Swelling of the tongue or throat 

• Feeling faint or dizzy 

• Blue/grey skin or lips 

• Loss of consciousness 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2].

Frequently asked questions about olanzapine

Will olanzapine make me gain weight? 
Yes, weight gain is common. A healthy diet and regular exercise can help manage it[1]. 

Can I drink alcohol while taking olanzapine? 
Avoid alcohol – it can increase side effects like drowsiness and dizziness[1]. 

How long does olanzapine take to work? 
Some people notice an improvement in a few days. Full effects may take 4-6 weeks[1]. 

Will olanzapine cause sexual problems? 
Antipsychotics can affect your sex life. If you find you have reduced libido or erectile dysfunction while taking olanzapine, talk to your doctor[1]. 

Is olanzapine addictive? 
No, but stopping it suddenly can cause withdrawal and a relapse of symptoms. Always follow your doctor’s advice[1]. 

Can I drive while taking olanzapine? 
Avoid driving if you feel sleepy or dizzy. Let your doctor know if your concentration is affected[1]. 

For the official NHS guide to olanzapine, visit their website.