The dose of Haldol Decanoate 50 or Haldol Decanoate 100 should be expressed in terms of its haloperidol content. The starting dose of haloperidol decanoate should be based on the patient's age, clinical history, physical condition, and response to previous antipsychotic therapy. The preferred approach to determining the minimum effective dose is to begin with lower initial doses and to adjust the dose upward as needed. For patients previously maintained on low doses of antipsychotics (. up to the equivalent of 10 mg/day oral haloperidol), it is recommended that the initial dose of haloperidol decanoate be 10–15 times the previous daily dose in oral haloperidol equivalents; limited clinical experience suggests that lower initial doses may be adequate.
Haldol is available in sterile vials containing 5 mg strength Haldol per 1 ml of fluid used for injection. Usual starting dose is -5 mg intramuscularly. Dose may vary according to patient response to the drug. Switch to an oral form of this drug is recommended as soon as possible. Haldol may interact with other drugs so the patient needs close observation or monitoring to determine if other side effects develop. Haldol should only be used during pregnancy or in women likely to become pregnant only if the benefit clearly justifies a potential risk to the fetus; fetal abnormalities and fetal exposure to Haldol in the third trimester have shown dependence at birth. Women who are breastfeeding should not take Haldol because the drug may affect the infant. Although reports of use for behavior modification exist, the drug is not approved for use in children.
It should not be used concomitantly with medications known to prolong the QTc interval (. 5-HT3 antagonists , tricyclic antidepressants , citalopram , etc.) as this may lead to an increased risk of QTc interval prolongation.   Neither should it be given concurrently with lithium (medication) as it may increase the risk of lithium toxicity and neuroleptic malignant syndrome .    It should not be given concurrently with other antipsychotics due to the potential for this to increase the risk of side effects, especially neurological side effects such as neuroleptic malignant syndrome .    It should be avoided in patients on CNS depressants such as opioids, alcohol and barbiturates.