Antipsychotic medications are often used to treat schizophrenia and come in oral form or by injection.

Schizophrenia is a progressive mental health condition. It can start with unassuming symptoms such as poor sleep and irritability, only to advance into more serious changes in function and psychosis in some cases.

Psychosis, or when the brain is unable to distinguish between what’s real and what isn’t, can come in the form of:

  • Hallucinations: Sensory experiences of things not present, such as seeing or hearing someone who isn’t really there.
  • Delusions: A stalwart belief in something proven to be untrue, no matter how much evidence is presented.
  • Disorganized thinking: Illogical patterns of thoughts and speech.
  • Movement disorder: Irregular, sometimes repetitive movement patterns.
  • Negative symptoms: A loss of functionality such as low energy, emotional “flatness,” or a loss of pleasure experience.

Symptoms of schizophrenia can be extremely challenging to overcome, but medications such as an antipsychotic injection may help keep debilitating features of this condition at bay.

Antipsychotic schizophrenia injections are considered long-acting injectables (LAIs). According to the National Alliance on Mental Illness, LAIs can last from 2 to 12 weeks, depending on the type you’re using.

LAIs fall into two categories:

First-generation LAIs used for schizophrenia injections have been around the longest and include:

  • fluphenazine decanoate (Prolixin Decanoate or “Dec”)
  • flupenthixol decanoate (Depixol)
  • haloperidol decanoate (Haldol)
  • zuclopenthixol decanoate (Clopixol)

Second-generation LAIs used for schizophrenia injections include some of the latest formulations and may come with fewer side effects. These LAIs include:

  • aripiprazole (Abilify Maintena, Aristada)
  • paliperidone (Invega Hafyera, Invega Trinza, Invega Sustenna)
  • risperidone (Risperdal Consta, Perseris)
  • olanzapine (Zyprexa)

According to research from 2018, antipsychotic injection works in the same manner as other antipsychotic medications — by targeting neurotransmitter receptors in the brain thought to be responsible for schizophrenia symptoms.

Though the exact modes of influence aren’t fully understood, experts believe antipsychotics influence the neuronal firing and plasticity of dopamine, adrenaline, and serotonin receptors.

What sets LAIs apart from many oral medications is the mechanism of delayed release.

Instead of relying on a daily pill to refresh your medication levels, a schizophrenia injection releases slowly over the course of a few weeks.

Invega Trinza, one of the most recent formulations of schizophrenia injection, is also one of the longest-lasting, with one dose offering 3 months of symptom control.

Newer generation antipsychotic injections appear to have similar safety and efficacy as their oral counterparts, according to research from 2017, but with several additional benefits.

A 2021 review on Invega Trinza found that the 3-month injectable was better at preventing symptom recurrence compared to the oral version of the medication. The authors noted this was likely due to the improved compliance factor of a longer dosing interval.

Invega Trinza was also found to be just as safe and effective as the oral version.

Similar efficacy and adherence benefits were seen in a 2017 review when LAIs were used to treat schizophrenia in children and adolescents.

In addition to compliance and consistent dosing, there may be other benefits to using a schizophrenia injection, including:

  • medical professionals can monitor adherence
  • interacting with your healthcare team more frequently
  • lower chance of accidental or deliberate overdose
  • fewer hospitalizations or symptom recurrences
  • lower incidence of side effects

If you and your doctor have decided to try a schizophrenia injection, what happens next can vary depending on the brand, your current medication status, and your history of treatment.


Before starting any medication, a healthcare or mental health professional will likely review your medical history, symptoms, and influencing factors such as family health, lifestyle habits, or environmental exposures.

You may also have a physical examination, diagnostic imaging, or laboratory testing to ensure there are no underlying conditions that might complicate the use of a schizophrenia injection.

The injection

If this is your first time on an LAI, you may also need to take an oral version of the medication to give the injectable time to start working.

It can take up to 6 weeks for your medication to fully kick in.

Receiving the schizophrenia injection takes only a moment. It’s generally administered in the muscle of your arm or buttocks.

The most common side effect of the injection is site irritation or pain, according to a 2021 review. Most mild injection site reactions resolve after 1 to 2 days.

Excessive amounts of swelling, redness, unbearable soreness, or signs of a severe allergic reaction should be immediately brought to the attention of your doctor.

Medical support will also be on the lookout for symptom breakthroughs and side effects during this time that may indicate a medication or dosing change is required.

Your return appointments will be likely set up before you leave your current visit.

Overall, LAIs and oral medications share the same list of side effects, though LAIs may have a lower rate of occurrence.

Common antipsychotic side effects include:

  • increased appetite
  • weight changes
  • dizziness
  • drowsiness
  • nausea
  • dry mouth
  • restlessness

Less commonly, antipsychotic use may result in more serious side effects such as:

  • tardive dyskinesia (movement disorder)
  • sexual dysfunction
  • increased chance of diabetes
  • vision changes
  • hyperprolactinemia (milk production)

If you’re interested in learning more about using a schizophrenia injection for symptom management, a healthcare or mental health professional can go over the options.

You can also learn more about schizophrenia or LAIs for treatment by calling the SAMHSA National Helpline at 800-662-4357.

To locate care facilities in your area, you can visit the SAMHSA service locator here.

If you’re still unsure where to start, you can check out Psych Central’s hub on finding mental health support.

If you’ve found it challenging to adhere to an oral medication schedule in the past, you might benefit from a long-term schizophrenia injection.

In addition to stabilized, consistent dosing, you may also find schizophrenia injections come with fewer side effects, fewer symptom breakthroughs, and improved control of treatment.

Consider reaching out to a mental health professional to learn more about antipsychotic injections and how they may work for you.