Headmeds fills the medicines information gaps for young people - things you might want to know about meds like will it affect my sex life? Can I still study?  Can I drink?
Headmeds does not give medical advice so this is just general information.
Each medicine has a balance of good and bad effects, and each person gets their own individual effects.
You might want to know just one thing about your medicine, but on each page we have given you the ‘safety headlines’. Please read them as they are important.
We have included lots of information about each medicine - but if you want all the details, please look at the patient information leaflet - which is inside every pack. These leaflets are also at www.medicines.org.uk - where there will be the most up-to-date information.

Safety headlines

• If you have taken more olanzapine than it said on the label, you must see a doctor quickly – even if you do not feel any different.
• Olanzapine can sometimes cause serious side effects. Tell your doctor immediately if you experience unusual movements (mainly of the face or tongue). Go to hospital immediately if you think you may have developed a blood clot (symptoms are usually swelling, pain and redness in the leg); a clot may travel through blood vessels to the lungs causing chest pain and difficulty breathing. Also go to hospital if you develop a combination of fever, faster breathing, sweating, muscle stiffness or drowsiness; and tell them that you are taking olanzapine.
• Stopping olanzapine suddenly can cause withdrawal effects, and stopping it too early could cause your illness to come back. See your doctor if you want to stop taking olanzapine because it is better to come off it gradually.
• You might feel sleepy or dizzy in the first few days after taking olanzapine – do not drive a car, ride a bike or operate machines until you see how this affects you.
• If you are pregnant, or thinking of becoming pregnant, please read the pregnancy section (see “Sex, drink, weight and everything else”) because olanzapine may affect the developing baby.

Basic details

The tablets contain lactose, the orodispersible melting tablets contain aspartame and gelatin.

• The olanzapine tablets that you swallow may not be suitable for you if you have problems eating some sugars or dairy (milk-based) foods, as they contain lactose.
• The olanzapine orodispersible (‘melt in your mouth’) tablets contain aspartame, which can be a problem for people who have a condition called phenylketonuria.
• The olanzapine orodispersible tablets also contain gelatin.

How does olanzapine work?

• There is a naturally occurring chemical messenger ('neurotransmitter') in the brain called dopamine.
• Dopamine is the chemical messenger in the brain mainly involved with thinking, emotions, behaviour and perception.
• In some illnesses, this dopamine may be overactive, which upsets the normal balance of chemicals in the brain.
• This excess activity of dopamine produces some of the symptoms of the illness.
• The main effect that olanzapine has is to block some dopamine receptors in the brain, correcting the overactivity of dopamine.
• Olanzapine also has effects on other neurotransmitters in the brain such as serotonin (5-HT) receptors, which may also contribute to the beneficial effects of olanzapine.

You should take olanzapine as agreed with your doctor.

• You will get the best effect from olanzapine if you take it regularly every day.
• Make sure that you know your dose. If it is not written on the label, check it with your pharmacist or doctor.
• You may start with a low dose that increases slowly to your normal dose over the first few days. This is more likely to happen for women who are non-smokers, as the medicine stays longer in their body than other people.
• You will usually take your dose once a day.
• It is usually recommended to take your olanzapine dose at bedtime because olanzapine can cause sleepiness as a side effect.
• However, it is important to choose a time of day to take it that you can easily remember, which could be bedtime, a mealtime, or when you brush your teeth.
• You can take it before or after food.
• For the normal coated tablets, swallow them whole with a drink of water - if you chew it, it tastes bitter.
• For the orodispersible (‘melt in your mouth’) tablets, put it on your tongue and let it dissolve there. You can also dissolve it in a glass of water, orange juice, apple juice, milk or coffee and then drink it all down.
• A doctor or nurse can use the long-acting injection in your bottom to give you a long-acting dose of olanzapine that lasts for 2 or 4 weeks – ask your doctor or nurse how often you have to come back.
• You may have a tablet at the same time – under the supervision of a doctor.
• The injection should change from the left buttock to the right side and back each time, so it’s not in the same place all the time.
• Every time you have the injection, you will be asked to wait there for at least 3 hours so that they can check that the injection is not giving you too much olanzapine. Someone will check that you are OK before you leave.
• The good thing about this is that you don’t have to remember to take your medicine every day. It is slowly working in your body all the time between injections.

What to do if you miss a dose of the tablets:

• If you remember later during the day, take it as soon as possible.
• If you forget to take it by bedtime, just start again on the next day.
• Do not take a double dose.
• If it is less than 12 hours before your next dose of olanzapine, then do not take the missed dose because taking the doses too close together could cause more side effects.

What to do if you miss an injection:

• If you miss your appointment for your injection, contact your doctor or nurse straight away to make another appointment.
• It is very important to have the injection every 2 or 4 weeks.

What might happen?

• If you forget to take your tablets for a while, or you miss an injection, you may start getting your old symptoms back. This means that you should talk to your doctor about it.

You must go to A&E if you take too much 

What to do if you take too much:

• If you have taken more olanzapine than it said on the label, you must get help quickly – even if you do not feel any different.
• Go to A&E. Take your medicine with you, to show to the doctors. Tell them how much you have taken.
• Get a friend to go with you, if you can, just in case you feel ill on the way.

You might get any of the following signs:

• rapid beating of the heart
• agitation/aggressiveness
• problems with speech
• unusual movements (especially of the face or tongue)
• reduced level of consciousness or coma
• confusion
• seizures (epilepsy)
• a combination of fever, faster breathing, sweating, muscle stiffness and drowsiness or sleepiness, slower breathing, aspiration (breathing in vomit, mucus, or blood), high blood pressure or low blood pressure, and unusual rhythms of the heart.

It can take 4-6 weeks for olanzapine to show its full effect, but some people get good effects right from the first week.

• Research evidence says that it takes 4-6 weeks for olanzapine to show its full effect.
• Some studies now, however, show a good effect for some people within the first week of taking olanzapine.
• You should stay in touch with your doctor to see how it goes over the first few weeks. They might do some tests to check your symptoms.
• If you have had no good effects after 2-3 weeks, your doctor may increase the dose or change the medicine
• Your doctor might start you on a low dose and then increase it slowly over 2-4 weeks to your full dose.
• If you are starting on the long-acting injection (Zypadhera™), it can take a few days for the first injection to start working.
• If you were already on olanzapine tablets, you may continue with them for those first few weeks on the injection, but you can start the injection on its own.

Many people take olanzapine for a few years.

You and your doctor should talk about how long you need to take olanzapine.

• How long you need to take olanzapine for depends on what condition you are taking it for. You should discuss how long you need to take it for with your doctor.
• If you stop the olanzapine, you will go back for checks to see that your old symptoms do not come back.
• For psychosis or schizophrenia, if you have had one episode of illness, then it is best for you to keep taking olanzapine for at least two years to reduce the chances to reduce the chances of becoming ill again. If you have had more than one episode of illness, then a period of at least five years is recommended.
• If you have been taking olanzapine to treat bipolar mania or bipolar depression, then after a few weeks you will need to discuss long-term medicines for your bipolar disorder with your doctor. This is to help stop the illness coming back.
• For bipolar disorder, it is important to remain on medicines in the long-term because every time you become ill, there is more chance of you becoming ill again. Olanzapine can be used as a long-term medicine, but lithium is thought to be the best long-term medicine for bipolar disorder. You should discuss your options with your doctor.
• For schizoaffective disorder, it is probably best to keep taking the olanzapine for a number of years to reduce the chances of the illness coming back. We know less about schizoaffective disorder, but it has some similarities to bipolar disorder and some similarities to schizophrenia.
• Depression is usually treated with an antidepressant medicine, and olanzapine is sometimes added to an antidepressant for more severe depression. For people with severe depression, it is best to continue the antidepressant medicine for at least two years to stop the illness from coming back. The doctor is likely to recommend continuing olanzapine for at least a few months.
• For eating disorders, olanzapine should be taken for several months, or sometimes years, to reduce the chances of the eating disorder getting out of hand again.

Reference sources

• Zyprexa tablets SPC last updated 18.10.16 Available online
  http://www.medicines.org.uk/emc/medicine/614 accessed 18/01/2017
• Zyprexa tablets PIL last updated 17.10.16 Available online http://www.medicines.org.uk/emc/medicine/14159 accessed 18/01/2017
• Zypadhera injection SPC last updated 18.01.16 Available online http://www.medicines.org.uk/emc/medicine/21361 accessed 18/01/17
• British National Formulary (BNF) 72nd edition, 2016.
• British National Formulary for Children (BNFc) 2016-2017, 2016.
• Taylor D, Paton C, Kapur S. Maudsley Prescribing Guidelines in Psychiatry, 12th edition. Oxford: John Wiley & Sons, 2015
• WADA Prohibited List 2015. Available online at http://list.wada-ama.org/ accessed 12.08.2015.
• Neal MC. Medical Pharmacology at a Glance (7th Edition). Oxford: John Wiley & Sons, 2012
• Royal Pharmaceutical Society of Great Britain. Medicines Ethics and Practice (37th edition). London: RPS, 2013
• Bumps – best use of medicines in pregnancy. Olanzapine Jan 2015. Accessed via http://www.medicinesinpregnancy.org/Medicine--pregnancy/Olanzapine/
• www.choiceandmedication.org accessed 12.08.15 (normally accessible for free via your mental health trust website.
• NICE CG178 Psychosis and Schizophrenia in adults. Feb 2014. Available online www.nice.org.uk
• NICE CG155 Psychosis and schizophrenia in children and young people. Jan 2013. Available online www.nice.org.uk
• NICE CG185 Bipolar disorder: assessment and management. Sep 2014. Available online www.nice.org.uk