Explains what antipsychotics are used for, how the medication works, possible side effects and information about withdrawal.

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What are the safety issues?

This page covers safety considerations regarding:

For safety considerations if you're pregnant or breastfeeding, see our page on antipsychotics in pregnancy.

Remember: when thinking about taking any antipsychotic safely, you'll also need to be aware of risks around dosage and side effects. If you have any concerns at all about being prescribed an antipsychotic, make sure you discuss them with your doctor.

Before you take any medication

Before you decide to take any medication, you should make sure you have all the facts you need to feel confident about your decision. For guidance on the basic information you might want to know about any drug before you take it, see our pages on:

What tests do I need before taking an antipsychotic?

Before you start taking an antipsychotic, your doctor should do the following tests to assess your physical health:

  • Physical examination (including asking you questions about your health and lifestyle) to record:
    • your weight
    • your waist size
    • your blood pressure and pulse rate
    • your diet and level of physical activity
    • whether you show any signs of movement disorders
  • Blood tests to measure your:
    • blood sugar
    • haemoglobin (red blood cells)
    • blood fats (cholesterol)
    • prolactin level – this is the hormone which stimulates breast tissue development and milk production, so levels are normally low for both men and women, unless you're a women who is pregnant or breastfeeding
  • ECG (heart test), but only if:
    • you have high blood pressure or any other symptom that may relate to your heart
    • you have a family history of heart problems
    • you're going to be admitted to hospital as an in-patient
    • an ECG is particularly recommended for the specific drug that your doctor is considering prescribing for you

Will I need more tests after I start taking it?

After you start taking the medication, your mental health team will need to continue to monitor all the above aspects of your physical health regularly. They will also need to monitor and record:

  • whether you're taking the drug in the way you're supposed to
  • whether it's actually helping you
  • what side effects it's causing – especially any that might be confused with symptoms of psychosis, such as agitation

If you're on a high dose of antipsychotics, you should be given an ECG every one to three months because antipsychotics can sometimes cause heart problems as a side effect. The risk is greater with higher doses. Whatever your dose, if you have unexplained blackouts, you should let your doctor know and they should monitor your heart rhythm regularly.

If you've been on the drug for a year and are getting on well with it, your GP can monitor your physical health instead of your mental health team. Your doctor should review your treatment at least once a year to check whether it's still working well for you – but you can ask them for a review whenever you want one. You can see the screening guide they may use here.

What if I have a medical condition?

If you have any of the following conditions, your doctor should use particular caution when prescribing you an antipsychotic. They may also need to monitor you even more regularly to check its effects:

  • liver or kidney disease
  • cardiovascular (heart and circulation) disease – or a family history of it
  • diabetes – or a family history of it
  • Parkinson’s disease
  • epilepsy
  • depression
  • myasthenia gravis (a rare disease affecting nerves and muscles)
  • an enlarged prostate
  • glaucoma (a serious eye disease)
  • lung disease with breathing problems
  • certain blood disorders

If you have any medical condition at all (even if it's not listed here) make sure that you tell your doctor about it so they can consider it when prescribing your medication.

In some medical circumstances, your doctor may decide it's not safe to prescribe you an antipsychotic at all. For example, you should never be given an antipsychotic if:

  • you have phaeochromocytoma (a type of tumour causing very high blood pressure)
  • you are semi-conscious, unconscious or in a coma

What if I'm an older person?

If you're an older person, your doctor will need to be particularly cautious when prescribing an antipsychotic, and they may need to adjust your dosage. This is because:

  • the medication is more likely to cause your blood pressure to drop when you stand up (which can lead to falls) and more likely to cause both high and low body temperature
  • as you get older your body becomes less efficient at dealing with drugs generally, so you're likely to need a smaller dose – higher doses will carry greater risks

Could they interact with other drugs?

Combining other medication with antipsychotic drugs can sometimes cause unpleasant or dangerous interactions. You should always check with your doctor or pharmacist before taking any drugs together, or closely following one another, in case they could interact with each other badly.

This table lists the main interaction risks between antipsychotics and other psychiatric medications. To learn about the interaction risks of a specific drug, you can look it up in our antipsychotics A-Z.

Other psychiatric medications Interaction risk with antipsychotics
all drugs that have antimuscarinic properties

All antipsychotics can cause antimuscarinic side effects. Combining them with other drugs that also have antimuscarinic properties is likely to make these side effects worse.

This particularly applies in the case of:

Anti-Parkinson’s drugs are also antimuscarinic. It's possible that an anti-Parkinson's drug could interact with your antipsychotic to make you delirious, which may be confused with your psychotic symptoms.

certain sleeping pills and minor tranquillisers

These can increase the sedative action of all antipsychotics, so they will make you feel even more drowsy. This is particularly true of:

  • the minor tranquillisers used for anxiety (buspirone, pregabalin and meprobamate)

  • benzodiazepines

  • the 'z-drugs': zolpidem, zopiclone and zaleplon


(a mood stabiliser)

Taking carbamazepine with antipsychotics has the following risks:

  • it increases the risk that you might experience unpleasant side effects

  • it can make your body process the following antipsychotics faster, which makes them less effective: aripiprazole, clozapine, haloperidol, olanzapine, paliperidone, quetiapine, risperidone

tricyclic antidepressants

Taking a tricyclic antidepressant at the same time as antipsychotic medication increases the risk of causing dangerous disturbances to your heart rhythm. This especially applies to fluphenazine, haloperidol, risperidone and sulpiride.

(an antidepressant)

First generation antipsychotics can all interact with trazodone. This can increase the risk of:

  • severe side effects

  • dangerous disturbances to heart rhythm

  • experiencing a sudden drop in blood pressure when you stand up

(a mood stabiliser)

Taking lithium at the same time as an antipsychotic can increase the risk of:

  • side effects such as muscular disorders (particularly with the first generation antipsychotics)

  • serious blood disorders (particularly with clozapine)

  • neuromuscular side effects (with flupentixol, sulpiride, haloperidol and risperidone)

  • neurotoxicity (a poisonous effect on the nervous system)

If your doctor decides to prescribe an antipsychotic alongside lithium, they should start it at a lower dose than usual.

Over-the-counter drugs

You should get advice from the pharmacist or another qualified professional before taking any non-prescription medicine – including complementary or alternative medicines – with your antipsychotic, so they can can tell you about any potential risks.

Alcohol and street drugs

  • Drinking alcohol can increase the sedative action of all antipsychotics, so it will make you feel even more drowsy. You might want to ask your doctor or pharmacist whether it’s safe to drink with the drug you've been prescribed, and take extra care to know your limits.
  • It's possible that street drugs may interact with antipsychotics. For example, if you take amphetamines with chlorpromazine, the effects of one or both can be reduced. See our pages on the mental health effects of street drugs for more information. You can also visit the FRANK website for confidential advice on street drugs.

This information was published in 2016. We will revise it in 2018.

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