What should clinicians know about haloperidol decanoate (“Haldol Dec”)?

Haloperidol decanoate is one of the first-generation antipsychotics available as long-acting antipsychotics available in the United States.

Haloperidol Decanoate



Dosing available as prefilled syringes

50mg/mL and 100mg/mL vial concentration available.

Recommended starting and maintenance dose

A standard maintenance regimen will be 10 to 15-times the daily, oral haloperidol dose (e.g., 10 mg haloperidol daily corresponds to Haldol Dec 100 or 150 mg IM every four weeks). 
Highest recommended dose is 450 mg/month.

Drug Metabolizing Enzyme


Loading dose

More aggressive loading-dose strategies have been published (e.g., giving 100 mg every week for 4 weeks). Be careful, however, to avoid prolonged extrapyramidal symptoms, particularly in antipsychotic-naïve patients. Do not give more than 100 mg as the initial Haldol Dec injection.

Oral overlap

Continue the oral dose for the first 2-3 injections if not using loading dose

Establishing tolerability

Prior to initiating Haldol Dec, establish tolerability with oral haloperidol in haloperidol-naïve patients.
In young patients who are at risk for extrapyramidal symptoms (e.g., an acute dystonic reaction), consider temporarily adding an anticholinergic during the initiation phase.


Room temperature. Haldol Dec is directly drawn up from vial that can be stored after each use and used until empty.

Reconstitution or mixing

50mg/mL and 100mg/mL vial concentration available.

Injection site

Deltoid or gluteal injections are both possible; the site can be chosen based on patient preference. Alternate sites and use appropriate needles for deep intramuscular injection. Do not inject more than 3 cc volume per injection site.
Use Z-track technique to avoid leakage.

Injection interval

Haloperidol Dec is typically given IM every four weeks. However, reducing the injection interval (rather than the individual dose) can be used to increase steady state haloperidol plasma levels.


As this is a sesame oil vehicle, it may be pulled out of vial with a larger gauge needle (i.e. 18 gauge) then injected with a new, smaller gauge needle (i.e. 21 gauge) for patient comfort

Administration considerations

Haldol Dec is oil-based, which is more painful than water-based long-acting injectables. You also will need to push harder.
Be careful to select the correct concentration: Haldol Dec is available as 50 mg/cc and as 100 mg/cc. Consider only using one concentration in your clinic to avoid dosing mistakes.

When a dose is missed

If the second or third doses are missed, Haldol Decanoate should be administered not later than 5 weeks after the last injection.
If the fourth or subsequent doses are missed, Haldol Decanoate should be administered not later than 8 weeks after the last injection.

See more information in this tip.



Additional information

Sesame oil base - check for sesame allergy.

Dose Conversion of Oral Haloperidol to Haloperidol Decanoate LAI

PO Dose - Haloperidol

LAI/IM Dose - Haloperidol Decanoate

Initiate LAI dose – for elderly, debilitated, or stable on low doses of oral haloperidol 

10-15x PO dose

Maintenance LAI dose – for stabilized or elderly patients

10-15x PO dose every 4 weeks

Initiate LAI dose – for patients with high relapse risk / higher dose

20x PO dose

Maintenance LAI dose – for patients with high relapse risk / higher dose

10-15x PO dose every 4 weeks

General conversion formula: For each 5 mg/day oral, give 50-75 mg Decanoate every 4 weeks.

Recommended available dose formulations include 50 mg/ml strength, in 3 ml multiple dose vials or 100 mg/ml strength, in 5 ml multiple dose vials.

Dose reduction may be necessary for CYP450 interactions of side effect intolerance.

1. Janssen Pharmaceuticals. (2019). Haloperidol decanoate for IM injection only.
2. American Psychiatric Association. (2020). The American Psychiatric Association Practice Guideline for the Treatment of Patients With Schizophrenia. American Psychiatric Association Publishing. https://doi.org/10.1176/appi.books.9780890424841

FDA Medication Label

Information on this topic is found in the FDA medication label. Not all information in the FDA medication label is included here, and clinicians should read the entire FDA medication label before making treatment decisions.

Prescribing should always be informed by the FDA medication label. Medication labels can be found by searching Drugs@FDA at the FDA website. Labels are also available using the Drugs@FDA app for Apple or Android devices.

Labels change over time, and the current label should always be consulted. Here is the most recent label, at time of writing.

If you would like more information on this topic, or would like to provide any feedback, please send us a message using our consultation system. Be sure to let us know about which tip you are writing. We would love to hear from you, and the consultation system is free to use and confidential. Thank you!


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