How it works
What does quetiapine do?
Dopamine is a chemical messenger (‘neurotransmitter’) in the brain mainly involved with thinking, emotions, behaviour and perception.
In some illnesses, there may be too much dopamine, causing some unwanted symptoms. The main effect that quetiapine has is to block the effects of dopamine in the brain, resulting in a reduction of symptoms.
Quetiapine also has effects on other neurotransmitters in the brain such as serotonin, and its beneficial effects may be related to this as well.
How long does quetiapine take to start working?
Many people say that it takes four to six weeks for quetiapine to show its full effect. However, some people experience benefits sooner than this.
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 two to three weeks, your doctor may increase the dose or change the medicine.
Your doctor will start with a low dose, which they will increase slowly until you find a dose that is effective for you. This may take several days or weeks.
How long will I need to take quetiapine?
You and your doctor should talk about how long you need to take quetiapine before you start your treatment.
If you take quetiapine for mania, bipolar depression or schizophrenia you will probably take it for a few years, otherwise your old symptoms can come back.
If you stop the medicine, you will go back for checks to see that your old symptoms do not come back.
Your doctor needs to know if...
You need to talk to your doctor or pharmacist before starting treatment with quetiapine if you have any of the following:
- heart problems, such as a very fast heart beat or prolonged QT on an electrocardiogram (ECG), or if you are taking any medicines that affect the way your heart beats
- low blood pressure
- a stroke
- problems with your liver
- seizures (fits)
- low levels of white blood cells
- blood clots, or a family history of blood clots
- sleep apnea (a condition where you stop breathing for short periods during your normal nightly sleep)
You should only take quetiapine as agreed with your doctor.
Take your medicine at a regular time every day to get the best effect.
Make sure that you know your dose. If it is not written on the label, check with your pharmacist or doctor.
You will start with a low dose that your doctor will increase slowly to a dose that is effective for you. This may take several days or weeks.
You will usually take your dose once or twice a day.
It doesn’t matter what time you take it each day. Choose a time that you can always remember. This could be a mealtime, or when you brush your teeth.
You can take the ordinary tablets with or without food and they should be swallowed with a drink of water – the tablets have an unpleasant bitter taste if chewed.
The prolonged-release (long-acting) tablets should not be broken as they have a special system in them to deliver the medicine into your body slowly over a few hours.
You should take the prolonged-release (long-acting) tablets by swallowing them whole (do not chew or crush) with a glass of water on an empty stomach – one hour before food, or two hours after food.
What if I miss a dose?
If you remember later during the day, take it as soon as possible.
If you forget to take it by your next dose, just take the next dose at the correct time. Do not try to catch up on missed doses.
Do not take a double dose.
What will happen if I forget to take my quetiapine?
If you forget to take your tablets for a few days, you may start getting your old symptoms back or some withdrawal symptoms. Talk to your doctor if this happens.
Stopping the use of quetiapine
Once you start taking an antipsychotic, the brain adjusts to having a new level of dopamine around.
If you stop taking the antipsychotic all at once, or reduce the dose too much all at once, the balance starts to change again. You could get your old symptoms back or experience unpleasant side effects including feeling or being sick, difficulty sleeping, headache, diarrhoea, feeling dizzy or irritable.
It is better to agree stopping with a doctor who will reduce your dose gradually over several weeks.
You will probably go for checks after you finish to see that your old symptoms have not come back.
Some people have thoughts about harming themselves or taking their own lives soon after they stop this medicine – you must go straight to a hospital if this happens to you.
The information on this page was reviewed by the College of Mental Health Pharmacy in October 2019.