Paliperidone (Invega)

What it treats

Paliperidone is approved by the U.S. Food and Drug Administration to treat schizophrenia and to treat schizoaffective disorder, either on its own or added to a mood stabilizer or antidepressant. It is used for both acute episodes and long-term maintenance. This guide focuses on those uses.

Because it is the active metabolite of risperidone, many people who have done well on risperidone can transition to paliperidone, and many of the same clinical decisions apply. The long-acting injectable forms are especially relevant for people who prefer not to take a daily pill or who have had trouble staying on oral medication consistently.

How it works

Paliperidone is an atypical antipsychotic. Nerve cells in the brain communicate using chemical messengers, and two of them, dopamine and serotonin, are central here. In psychosis, dopamine activity in some brain circuits is thought to be too high, and paliperidone dampens that activity while also modulating serotonin signaling. That combined action is the shared mechanism of the atypical class.

Because paliperidone is 9-hydroxyrisperidone, it works essentially the same way risperidone does at the receptors that matter. The differences between the two are more about how the body handles the medication, and about the range of formulations available, than about what happens at the neuron.

Receptor mechanism (detail)

Paliperidone is a potent 5-HT2A and D2 antagonist, with meaningful activity at alpha-adrenergic (α1, α2) and histamine H1 receptors. In plain terms, it blocks a dopamine signal that is overactive in psychosis and blocks a serotonin signal that helps soften the movement side effects of pure dopamine blockade. The alpha and histamine activity explain some of the practical experience of taking it, occasional dizziness on standing, and some sedation, especially early on. Because D2 blockade is meaningful, prolactin elevation is common; among atypical antipsychotics, paliperidone and risperidone raise prolactin the most.

Potency and typical dosing pattern

Ranges are typical framework only, not a prescription for any individual. Paliperidone is a moderate- to high-potency antipsychotic by milligram.

For oral Invega, a common starting and target dose is 6 mg once daily, with a usual range of 3 to 12 mg per day. The tablet is an extended-release form and should be swallowed whole. For long-acting injectables, three options exist: Invega Sustenna is given monthly by a clinician, Invega Trinza is given every three months (used only after a person is stable on Sustenna), and Invega Hafyera is given every six months (used only after stability on Sustenna or Trinza). The every-six-months option is currently unique in psychiatry, no other antipsychotic offers that interval. The prescriber sets and adjusts the dose based on response, side effects, and other medications.

Safety monitoring

• Metabolic labs. Weight and BMI at baseline, weeks 4, 8, and 12, then quarterly. Fasting glucose or HbA1c and a lipid panel at baseline, three months, and at minimum annually. Paliperidone carries moderate metabolic risk, less than olanzapine or clozapine, more than lurasidone or ziprasidone.
• Blood pressure at baseline and periodically, including checking for a drop on standing.
• Prolactin. Paliperidone raises prolactin more than most other atypicals. Ask about breast tenderness, unexpected milk production, menstrual changes, and sexual side effects at each visit. A blood level is checked if symptoms suggest it.
• Movement effects. Ask about akathisia (restlessness) and stiffness at every early visit. An involuntary-movement screen (AIMS) every six months looks for tardive dyskinesia over the long term.
• ECG if there are other QT-prolonging medications or cardiac risk factors.

Metformin co-commencement. Aoife Carolan / Schizophrenia Bulletin guideline.

A clinical guideline led by Aoife Carolan strongly recommends co-commencing metformin alongside high-risk antipsychotics like olanzapine or clozapine. This proactive approach helps mitigate severe metabolic side effects, significantly reducing antipsychotic-induced weight gain and improving insulin resistance. The Schizophrenia Bulletin guideline states that when prescribing olanzapine or clozapine, metformin should be initiated immediately to prevent weight gain and cardiometabolic issues. Paliperidone is classified as medium-risk in the guideline; metformin is recommended when other cardiometabolic conditions are present, and metformin should be started if weight rises by more than 3 percent of pre-medication weight.

Typical titration used in the guideline: 500 mg once daily → 500 mg twice daily after one week → 500 mg increments every two weeks as tolerated → up to 1000 mg twice daily by about week six. Contraindicated with eGFR below 30 mL/min/1.73 m²; renal function is checked annually and metformin is held during acute illness or dehydration.

Source: Carolan A, et al. Metformin for the Prevention of Antipsychotic-Induced Weight Gain: Guideline Development and Consensus Validation. Schizophrenia Bulletin. 2025;51(5):1193 to 1203.

What to expect

Common side effects

Most people get some side effects. The common ones include:

• Restlessness or an inability to sit still, akathisia.
• Stiffness, tremor, or slowed movement, the parkinsonian side effects of dopamine blockade.
• Sedation, especially early on.
• Dizziness or lightheadedness on standing.
• Weight gain and increased appetite.
• Prolactin-related effects: breast tenderness, unexpected milk production, missed periods, and reduced sex drive or function.

Akathisia and stiffness are treatable and worth flagging early. Many of the milder early effects ease within the first weeks. If a side effect is severe, or it is not improving, that is a conversation to have with the prescriber rather than a reason to stop on your own.

Serious side effects and warnings

Serious problems are uncommon, but a few are worth knowing.

Boxed warning. Like all antipsychotics, paliperidone carries an FDA boxed warning that it increases the risk of death in older adults with dementia-related psychosis, and antipsychotics are not approved for that use.

• Metabolic effects. Weight gain, and rises in blood sugar and cholesterol, can happen over time and are monitored.
• Tardive dyskinesia. A movement disorder linked to long-term antipsychotic use, involving repetitive involuntary movements, often of the face or mouth. The risk rises with longer use.
• Neuroleptic malignant syndrome. A rare but serious reaction. Signs include high fever, muscle stiffness, confusion, and an unstable heartbeat or blood pressure. It is a medical emergency.
• Orthostatic hypotension. A drop in blood pressure on standing can cause dizziness or falls, especially in older adults.
• Prolactin elevation. Long-term high prolactin can affect bone density, fertility, and sexual function. Symptoms should be raised with the prescriber.

Sexual side effects

Paliperidone can affect sex drive, arousal, and function, and much of this is tied to prolactin elevation. Reduced desire, difficulty with arousal, and, in men, erectile problems or reduced ejaculation volume can occur. These are treatable, a dose adjustment, a switch to another medication, or specific treatment for the prolactin effect are all options. It is worth raising rather than living with.

Weight, appetite, and sleep

Weight gain is common, and appetite often rises. Weight, blood sugar, and cholesterol are checked periodically, and lifestyle steps and, when indicated, metformin can help. Sleep is usually easier rather than harder on paliperidone, since it can be mildly sedating. If sedation is a problem during the day, that is worth discussing with the prescriber.

Starting and dosing basics

This section is general background, not a dosing instruction for any individual. The right dose is a decision for a prescriber.

Oral Invega is an extended-release tablet taken once daily, swallowed whole rather than crushed or chewed. It can be taken with or without food. The long-acting injectable forms are given by a clinician in the office, on a monthly, three-month, or six-month schedule depending on which product is used. Switching between forms is done in a planned way by the prescriber, since each has its own loading and steady-state pattern.

Missed doses and interactions

If a dose of oral paliperidone is missed, the general guidance is to take it when you remember, unless it is almost time for the next dose. In that case, skip the missed dose and carry on. Don't take two doses to make up for one. For long-acting injections, missing a scheduled dose has its own rules, the clinician's office should be contacted so the correct restart plan can be used.

Paliperidone is largely cleared by the kidneys rather than heavily metabolized in the liver, so it has fewer drug interactions than some other antipsychotics. Even so, the prescriber and pharmacist need a full list of your medications and supplements, including over-the-counter ones. Alcohol is not formally prohibited, but it can worsen sedation and is generally best limited.

Stopping and tapering

Stopping paliperidone should be gradual and planned with a prescriber. The body adjusts to the medication over time, and stopping suddenly can cause a return of symptoms. For long-acting injections, the medication continues to be released for weeks or months after the last dose, so "stopping" is really a matter of not scheduling the next one and then watching over that release window. Deciding to stop because you feel better is understandable, but it is still worth doing slowly and with guidance.

Pregnancy and breastfeeding

This is an area where individual circumstances matter and the decision belongs with a clinician. Untreated psychosis carries its own significant risks during pregnancy, and paliperidone also passes into breast milk. None of that adds up to one answer that fits everyone. Anyone who is pregnant, planning a pregnancy, or breastfeeding should talk it through with their prescriber so the specific risks and benefits can be weighed for their situation. This is not medical advice.

Cost and generic availability

Oral paliperidone is available as a generic and is moderately priced, more expensive than generic risperidone but less than the brand-name Invega. The long-acting injectable forms (Sustenna, Trinza, Hafyera) are still brand-only and are considerably more expensive, though insurance and patient-assistance programs often cover them for people with schizophrenia. The brand and generic contain the same active medication and work the same way.

Common questions

How is paliperidone different from risperidone? Paliperidone is 9-hydroxyrisperidone, the same molecule the body makes when it processes risperidone. At the receptor, they are very similar. The differences are practical: paliperidone is cleared mostly by the kidneys rather than the liver, so it has fewer drug interactions, and it comes in extended-release oral and long-acting injectable forms that risperidone doesn't offer in the same way.

What are the long-acting injectables like? They are given by a clinician in the office. Sustenna is monthly, Trinza is every three months, and Hafyera is every six months. Most people start on Sustenna to make sure they tolerate paliperidone, then move to a longer interval if they and the prescriber agree. The injection is in the deltoid or gluteal muscle depending on the product.

Why is the every-six-months shot a big deal? Invega Hafyera is currently the only antipsychotic injection that can be given every six months. That is a meaningful change for people who value not having to take a daily pill or attend monthly injection visits. It is only used after someone is stable on shorter-interval paliperidone first.

Will it raise my prolactin? Often, yes. Paliperidone raises prolactin more than most other atypical antipsychotics. Symptoms are worth raising with the prescriber, because they are treatable.

Will it make me gain weight? Some weight gain is common. The metabolic risk is moderate, less than olanzapine or clozapine, more than lurasidone or ziprasidone. Weight, blood sugar, and cholesterol are monitored over time.

Questions to ask your prescriber

• What are we hoping this treats, and how will we know it's working?
• Which side effects should I expect early, and which ones should I call about?
• Is a long-acting injection an option for me, and what would that look like?
• What should I watch for in terms of prolactin symptoms?
• If we decide to stop it later, how would we do that safely?

Sources

This guide draws on current prescribing information and public health references. It is reviewed for clinical accuracy and updated as guidance changes, and current as of June 8, 2026.

• U.S. Food and Drug Administration. Prescribing information (DailyMed).
• MedlinePlus, U.S. National Library of Medicine.
• National Institute of Mental Health.
• American Psychiatric Association. Practice Guideline for the Treatment of Patients with Schizophrenia, 3rd edition.
• National Institute for Health and Care Excellence (NICE). CG178, Psychosis and schizophrenia in adults.
• American Diabetes Association / American Psychiatric Association. Consensus Statement on Antipsychotic Drugs and Obesity and Diabetes.
• Carolan A, et al. Metformin for the Prevention of Antipsychotic-Induced Weight Gain: Guideline Development and Consensus Validation. Schizophrenia Bulletin. 2025;51(5):1193 to 1203.