Depot antipsychotic injections

Depot antipsychotics are given as an injection. It slowly releases the antipsychotic medicine into your body over a few weeks.

On this page, you can find the following information:

What are ‘depot’ antipsychotics?

A depot injection is a slow-release, slow-acting form of your medicine. It isn't a different medicine – it's the same as the antipsychotic medicine you're used to taking in tablet or liquid form, but it's given by injection instead. A depot injection releases the medicine slowly over time, so the injection is given every 2 to 4 weeks. The effects are generally the same as medicines taken by mouth. 

When are depot antipsychotics used?

Depot injections might be a good option if you:

  • have difficulty remembering to take your medicine regularly 
  • have difficulty swallowing your medicine in tablet or capsule form
  • prefer not to have to think about taking your medicine every day.

It's important to discuss available treatment options with your healthcare provider, to see which might be the best for you. Read more about what to consider when deciding on having a depot injection.

You would usually only be given a depot injection if you've already been on your medicine (as a tablet, capsule or liquid) for a while, you know it's working well for you and you expect to keep taking it for a long time.

Examples of depot antipsychotics available in Aotearoa New Zealand

Not all antipsychotic medicines are available as depot injections. Examples of medicines that have a depot injection formulation are:

Atypical antipsychotics

Typical antipsychotics

  • flupentixol (Fluanxol)
  • fluphenazine (Modecate)
  • haloperidol (Haldol)
  • pipothiazine (Piportil)
  • zuclopenthixol (Clopixol)

Things to consider when deciding about a depot injection

  • Because the depot is given every few weeks, you don't have to remember to take your medicine every day.
  • They are a good option if you have difficulty swallowing medicine.
  • Some people may find having an injection unpleasant, although the pain is slight and doesn't last long (see below: how are the injections given).
  • It takes a long time to know the effect of changing the dose. If the dose is changed, you may not know what the effect of this change is for several weeks or months. 
  • If a particular dose is giving you side-effects, lowering it may make little difference for several weeks.

How are the injections given?

The injections are usually given every 2 to 4 weeks, depending on the medicine.

A doctor or nurse will give you the injection. You would never give this at home by yourself.

  • The injection is given into a large muscle, such as your buttock, or the largest muscle of your shoulder.
  • It's best to change the injection site every time you have your injection to help prevent injection site problems, eg, pain, redness, soreness, irritation, swelling, abscess and bleeding.
  • If you do have problems with your injection site, make sure you tell whoever gives you your medication. 

The first injection is usually a small dose (called a test dose) to check how your body copes with the injection. If there are no problems, then you can start having regular injections at a higher dose. After each injection, the medicine will stay in your body for several weeks.

Where can I have the injections done?

You can usually decide yourself where to have the injections. This might be at your local GP surgery, at a community mental health centre, at a special out-patient clinic or at your home, when a nurse visits you.

When can I expect to feel better?

Depot injections don't start working immediately, so you may need to continue to take your tablets, capsules or liquid for a time. It usually takes a few weeks before the benefits occur and for your symptoms to reduce. At first, most people find that the medicine helps them feel more relaxed and calm and with time other symptoms will improve.  

Would I still need to take antipsychotic tablets, capsules or liquid?

When you first start taking depot antipsychotics, the first injection won't start to work straight away, so during the first few weeks of treatment you may still need to take additional tablets, capsules or liquid, which can be taken by mouth.

Later, depending on how well the treatment is working, you may be able to stop taking the medicine in other forms. Your healthcare provider will monitor you to see how much and what type of medicine you need.

What happens if I miss a dose?

The injections are usually given every 2 to 4 weeks, depending on the medicine.

If you miss an injection, you should have another one as soon as you can. If you don't, over a few weeks the medicine will stop working and some of the old problems will come back, like hearing voices or feeling troubled or scared. You may start to feel worse than before you started the medicine if you keep missing the depot injections.

How long will I need to have the injections for?

Most people need antipsychotic depot injections for quite a long time, often years. If you stop your injections, your symptoms are likely to return, but this may not be for 3 to 6 months after stopping. If you want to stop taking the depot injections, talk to your doctor.

What about side effects?

Common side effects after having the injection include:

  • Pain at the injection site – this should pass quickly but if the area becomes red, swollen, or lumpy, tell your doctor.
  • Feeling dizzy or sleepy or having blurred vision – don't drive for a few hours after having the injection if you are affected.

Read more about the possible side effects of antipsychotic medicines.


  1. Depot medication Royal College of Psychiatrists
  2. Antipsychotic depot injections NZ Formulary
  3. Long-acting injectable antipsychotics – a practical guide for prescribers Psychopharmacology Institute
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland and Patrick Cabasag, Pharmacist Last reviewed: 26 Sep 2022