HeadMeds gives young people in the United Kingdom general information about medication. HeadMeds does not give you medical advice. Please talk to your Doctor or anyone else who is supporting you about your own situation because everyone is different. Please read more important details about our site.

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Return to Olanzapine overview
  1. Use and Action
  2. Warnings and side effects
  3. Sex, drink, weight and everything else
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You can drink alcohol while taking olanzapine, but it could make you very sleepy and make you fall over

  • You can continue to drink some alcohol while taking olanzapine, but having the two together might make you very sleepy or make you fall over.
  • If you drink a lot of alcohol, these effects will be much more serious.
  • Alcohol can also make the symptoms of your condition worse.
  • So, during the first few days, it might be best to stop drinking alcohol until you see how the medicine affects you.
  • If you want to drink alcohol, remember that you might be sleepy and make sure you can get home safely.

Do not drive a car or ride a bike just after you start taking olanzapine

  • Taking olanzapine may make you feel tired or dizzy when you start taking it.
  • This could affect you if you drive a car, ride a bike, or do anything else that needs a lot of focus. It might be best to stop doing these things for the first few days, until you know how it affects you.
  • Do not worry - most people drive as normal while taking olanzapine.

Try not to take olanzapine for the first time just before your exams.

  • Olanzapine can make you feel tired and dizzy, and can affect your memory.
  • You should talk to your doctor about any future exams if you are starting olanzapine.
  • You might decide together to delay starting it until you have done them.
  • You might find that it is better, however, to start olanzapine to improve your symptoms and your ability to study and do the exams.
  • You could take your olanzapine at night (if you do not do that already) to see if that is better for you.
  • Do not worry - most people do exams as normal while taking olanzapine.

Olanzapine is not a banned substance in sport

  • Olanzapine is not a banned substance in sport.
  • It can, however, make you feel tired or dizzy, so this might affect your performance in sports that need a lot of focus.
  • You need to see how it affects you.
  • Do not worry - most people do sports as normal while taking olanzapine.

Your weight can be affected by olanzapine.

  • A common side-effect of olanzapine is weight gain.
  • You need to have your weight checked regularly while you are taking it.
  • Talk to your doctor about this if it worries you.
  • It is thought that one of the reasons olanzapine causes weight gain is increased appetite, meaning that you eat more.
  • Making sure to do enough exercise and eat a healthy diet (with vegetables and fibre) can help you to avoid putting on too much weight.

Let your family and friends know you are taking olanzapine so they can support you and help you look out for side effects.

  • The side-effects of olanzapine might put a strain on your friendships and relationships, especially in the first few days of taking it.
  • You might feel very tired, and your memory might be affected.
  • These side-effects should get better after a few days.
  • You should then be getting the good effects of olanzapine, and that should improve your relationships in itself.
  • It might actually be a great idea to choose a good friend to tell about your medicine when you start taking it. (Or - even better - to take a friend with you to the doctor before you start taking the medicine!)
  • They could look at the medicine leaflet, or at this website.
  • They could help you to understand whether the medicine changes your behaviour, or gives you side-effects (sometimes it is hard for us to see it ourselves).

Olanzapine can have side-effects that might affect your sex life, but they should not last for long.

The good effects of olanzapine may have a good effect on your sex life as your symptoms settle and you can concentrate on your relationships.

There are some side-effects that include:

  • Feeling less interested in sex.
  • For women, very occasionally periods might stop, breasts might grow, and in very rare instances, some milk might flow.
  • For men, very occasionally breasts might grow, and they may have difficulty getting an erection.
  • If you gain weight, or get a rash, you may not feel as sexy.

Some of these effects should pass after the first couple of weeks. If they do not, and this is a problem for you, go back to the doctor and see what else you could try.

Olanzapine is unlikely to affect fertility, but you should talk to your doctor if you are planning to get pregnant.

  • Olanzapine may increase the level of a hormone called prolactin in the body for a short time when you start taking it, but not to a very high level.
  • If prolactin levels do rise for a short time after starting olanzapine, then women may find it more difficult to get pregnant, and men may find it more difficult to get their partner pregnant.
  • However, this is not a common problem for people who take olanzapine.
  • Men who take olanzapine and are having difficulties with sex or fertility should speak to their doctor about this.
  • Women who take olanzapine and want to become pregnant should talk to their doctor and also see below for more information about taking olanzapine during pregnancy.

Is it safe to take olanzapine in pregnancy?

  • Olanzapine is not seen as high risk and if regular medicine is keeping you well there may be more risk by changing. Olanzapine is an antipsychotic medicines. Taking antipsychotics can cause folate levels to become low. Low folate is not good for a healthy pregnancy. Taking 5mg folic acid a day before and during pregnancy can reduce the risk of your baby having spine problems.
  • Information on over 800 mums who took olanzapine suggests no increased risk of malformations, miscarriage or having a baby born early.
  • Olanzapine may slightly increase your chance of getting high blood pressure linked to pregnancy (pre-eclampsia), putting on extra weight and gestational (pregnancy- linked) diabetes.
  • Expect your blood sugar levels, weight and blood pressure to be more closely checked from month 4 onwards of your pregnancy
  • A blood thinning agent may be advised. This is because sometimes there can be a risk of getting a blood clot in the leg during pregnancy
  • Taking olanzapine close to delivery may lead to some discontinuation effects in your baby. These may include being irritable, crying or problems feeding and sleeping. These are usually mild and go away in a few days without treatment.

Remaining well is particularly important during pregnancy and while caring for a baby. For some women treatment with olanzapine in pregnancy may be necessary.

Please consult the Bumps website for more information, including specific information on olanzapine in pregnancy

Can I breastfeed if I am taking olanzapine?

  • Olanzapine gets into breast milk, but only in small amounts (around 1%).
  • Breastfeeding may help with any discontinuation effects
  • There is a risk of the baby becoming a little more sleepy if breastfed when the mother is taking olanzapine.
  • You should talk to the doctor if you are taking olanzapine and thinking of breastfeeding after you give birth to your baby.
  • Remember that it is important for you to stay well whilst you are bonding with and looking after your baby. This means that you may need to take olanzapine or another medicine for your mental health when breastfeeding.
  • You may also need to consider bottle feeding with formula milk if there are any problems with breastfeeding whilst taking medicines.
  • Talk to your doctor or midwife about your feeding options.
  • Make sure that your doctor, nurse, or health visitor checks your baby for any side effects. These can include:
  • Being extra sleepy
  • Having colic
  • Feeding problems
  • Being floppy
  • Poor weight gain
  • If there any problems, the doctor may need to reduce your olanzapine dose or switch to an alternative medicine.
  • The second half of the feed (also known as “hind milk”) may contain more olanzapine than the first half.
  • If your baby was premature or has health problems, then you will need to be extra careful about taking medicines whilst breastfeeding. Discuss this with your doctor.

If you start or stop smoking while you are taking olanzapine, you may have to change your dose.

  • Cigarette smoke affects the amount of olanzapine in your body.
  • If you smoke, you may need a higher dose of olanzapine than someone who does not smoke.
  • Tell your doctor if you smoke, so that you get the right dose for you.
  • If you stop smoking, the body olanzapine level rises and you might need to reduce your dose of olanzapine slowly over one week
  • If you (re)start smoking, you may need to increase it again
  • Go to your doctor for advice if you stop or start smoking.

Reference sources

Search www.medicines.org.uk to find patient information leaflets and prescribing information on olanzapine. Plain tablets, orodisperible tablets and injection are listed separately and the original brand is Zyprexa but there are many other manufacturers. The SmPC lists all the inactive ingredients in the product so you can check against any allergies. If you are still unsure about this then speak to your pharmacist.

  • British National Formulary (BNF) and British National Formulary for children. Download the BNF/BNFC app (blue background) on to your mobile device. No longer available for public access via the web 
  • Taylor D, Barnes T, Young A. Maudsley Prescribing Guidelines in Psychiatry, 13th edition. Oxford: John Wiley & Sons, May 2018. ISBN: 978-1-119-44260-8
  • Royal Pharmaceutical Society. Medicines Ethics and Practice (42nd edition). London: RPS, 2018. Standards for pharmacists to work to. It is not a free publication
  • World Anti Doping Agency WADA Prohibited List https://www.wada-ama.org/en/resources/science-medicine/prohibited-list-documents 
  • Choiceandmedication; an independent source of information on many mental health conditions and their medicines with easy to read fact sheets www.choiceandmedication.org Personal subscriptions to download the app available for £1 per month (with proportionate discounts for longer periods) but your local mental health Trust may subscribe and provide information sheets for free.
  • Best Use of Medicines in Pregnancy (BUMPS). Information sheets on drugs in pregnancy http://www.medicinesinpregnancy.org/ 
  • Drugs and Lactation Database (LactMed). Information on drugs in breastfeeding https://toxnet.nlm.nih.gov/newtoxnet/lactmed.htm
  • NICE CG178 Psychosis and Schizophrenia in adults. Updated March 2014. Available online https://www.nice.org.uk/guidance/cg178
  • NICE CG155 Psychosis and schizophrenia in children and young people. Updated October 2016. Available online https://www.nice.org.uk/guidance/cg155
  • NICE CG185 Bipolar disorder: assessment and management. Updated April 2018. Available online https://www.nice.org.uk/guidance/cg185