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.

Establishing Tolerability


  • 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.
  • 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).
  • 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.
  • Highest recommended dose is 450 mg/month.
  • The 1-year-relapse rate for 25 mg-50 mg-100 mg-200 mg IM every four weeks are 60-25-23-15%, respectively; for most people with chronic schizophrenia, 25 mg is too low.
  • There is no established protocol for Haldol Dec regarding switching schedule or oral cross coverage. The plan for cross coverage will depend on understanding that it can take a few injections to reach stable therapeutic levels, the risks in the individual patient regarding side-effects and reduction in medication effectiveness, and ongoing monitoring of effectiveness and side effects in the patient.

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

  • Therapeutic drug monitoring (TDM) can guide dosing. A haloperidol plasma level between 1 and 10 ng/mL is a target range, and this can be utilized when encountering clinical problems.

Practical issues (including administration)

  • Haldol Dec does not need to be refrigerated or reconstituted. Haldol Dec is directly drawn up from vial that can be stored after each use and used until empty.
  • 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.
  • 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.
  • Haldol Dec is oil-based, which is more painful than water-based long-acting injectables. You also will need to push harder.

FDA Medication Label

Information on this topic is found in the FDA medication label.  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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