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Haldol Injection

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Generic Name: haloperidol decanoate
Product Name: Haldol Injection

Indication: What Haldol Injection is used for

Haldol is used to control the symptoms of mental illnesses with disturbances in thinking, feelings and behaviour.

Your doctor may have prescribed Haldol for another use. Ask your doctor or healthcare professional if you have any questions about why this medicine has been prescribed for you.

Haldol is not addictive.

Action: How Haldol Injection works

Haldol is a long-acting antipsychotic. It works by correcting the chemical imbalances in the brain, which may cause mental illness.

Haloperidol decanoate is a long-acting form of haloperidol. The basic effects of haloperidol decanoate are the same as those of haloperidol with the exception of duration of action. When it is administered as an intramuscular depot injection in sesame oil, esterases present in the blood and tissues hydrolyse haloperidol decanoate to provide a slow release of the active neuroleptic haloperidol from the depot into the systemic circulation. Haloperidol blocks the effects of dopamine and increases its turnover rate, however, the precise mechanism of action is unknown.

Each mL of Haldol Injection contains 50 mg haloperidol (as decanoate) as the active ingredient. Other ingredients are sesame oil vehicle and benzyl alcohol.

Dose advice: How to use Haldol Injection

Before you are given Haldol

When you must not be given it

Do not give Haldol to anyone who is unconscious or in a coma.

You must not be given Haldol if you:

  • Have severe drowsiness and slowness due to illness or the use of alcohol or medicine;
  • Suffer from severe depression;
  • Have or have ever had muscle stiffness, restricted or uncontrollable movement due to certain medical conditions, such as Parkinson’s disease;
  • Have an allergy to Haldol or any of the ingredients listed here. Signs of allergy may include skin rash, itching, shortness of breath, and/or swollen face that may lead to difficulty breathing or swallowing. If you think you are having an allergic reaction, tell your doctor immediately or go to the Accident and Emergency department at the nearest hospital.

Do not give Haldol if the packaging is torn or shows signs of tampering and if it is beyond the expiry date (month and year) printed on the pack.

Before you are given it

You must tell your doctor if you:

  • Are pregnant or planning to become pregnant. Like most antipsychotic medicines, Haldol is not recommended for use during pregnancy. Discuss with your doctor the risks and benefits involved in taking it;
  • Are breastfeeding or wish to breastfeed;
  • Suffer from loss of contact with reality and inability to think and judge clearly, or from a general decline mental ability (e.g. dementia related psychosis);
  • Have ever had bleeding in the brain, or your doctor has told you that you are more likely than other people to have a stroke;
  • Have or have ever had a heart problem, such as an unusual heartbeat or a fast heartbeat, or are taking a heart medication;
  • Have or have ever had low blood pressure;
  • Have or have ever had a rare heart disorder known as QT-prolongation which sometimes runs in families;
  • Have or have ever had uncontrolled movements of the tongue, mouth, cheeks or jaws which may progress to the arms and legs (also known as tardive dyskinesia);
  • Have or have ever had a sudden increase in body temperature, extremely high blood pressure and severe convulsions (also known as neuroleptic malignant syndrome);
  • Have or have ever had epileptic fits or convulsions;
  • Have or have ever had liver disease;
  • Have a very active thyroid gland (hyperthyroidism);
  • Have had blood clots, or a family history of blood clots. Blood clots in the lungs and legs have been seen in patients taking antipsychotic medicines;
  • Experience a significant increase in weight while taking other antipsychotic medications. Clinically significant weight gain has also been reported in patients taking this medicine.

Tell your doctor if:

  • You are taking medicines or have medical conditions which may cause an imbalance of potassium levels in your blood;
  • You suffer from an imbalance of electrolytes (naturally occurring chemicals present in body fluids, that are needed for normal body functions).

If you have not told your doctor or pharmacist about any of the above, tell them before you are given Haldol.

Your doctor will advise you on whether you should receive Haldol or whether to adjust the dose or alter your treatment.

Taking other medicines

Tell your doctor or pharmacist if you are taking any other medicines, including medicines you can buy without a prescription from a pharmacy, supermarket or health food shop.

In particular, tell your doctor or pharmacist if you are taking any of the following:

  • Medicines used to control depression or mood swings (such as nefazodone, buspirone, venlafaxine, fluvoxamine, fluoxetine, paroxetine, sertraline, lithium, alprazolam, chlorpromazine);
  • Antipsychotic medicines used to treat mental illness;
  • Promethazine (which is used to treat allergies, nausea or vomiting);
  • Antifungal medication (such as ketoconazole and itraconazole);
  • Medicines known to cause electrolyte imbalance or imbalance of naturally occurring chemicals present in body fluids, that are needed for normal body functions;
  • Alcohol or medicines which make you feel drowsy or slow your reactions, such as sleeping tablets, tranquillisers or strong painkillers;
  • Medicines used to lower high blood pressure and heart conditions (such as methyldopa);
  • Medicines used to treat fast or irregular heartbeats (arrhythmia) such as quinidine;
  • Certain cough and cold preparations and weight reduction medicines containing substances such as adrenaline;
  • Medicines that prevent adrenaline working, such as guanethidine;
  • Antibiotics such as rifampicin;
  • Medicines used to prevent travel sickness, treat Parkinson’s Disease or relieve stomach cramps or spasms (anticholinergics);
  • Medicines used to treat Parkinson’s disease, such as levodopa;
  • Medicines used to treat epilepsy (such as carbamazapine, phenobarbital);
  • Medicines used to slow or prevent blood clotting (anticoagulants).

These medicines may be affected by Haldol or may affect how well Haldol works. Your doctor or pharmacist can tell you what to do if you are taking any of these medicines.

Effects on driving and operating machinery

Haldol can affect your alertness and ability to drive and operate machinery. Do not drive or operate machinery until your doctor says it is safe.

Do not drink alcohol. Haldol can increase the effects of alcohol.

Using Haldol

How it is given

Haldol will be given as an injection by your doctor or nurse into a muscle in the buttocks.

Haldol should not be given into a vein.

It is usually given every four weeks, however, your doctor may lengthen or shorten this time.

Your doctor will decide how much Haldol you will be given. This will depend on your physical conditions such as your age, body weight, your medical history and conditions.

Your doctor will monitor you closely when you start receiving Haldol injection. Your dose and how often the injection is given may be altered until the medicine controls your symptoms. Follow your doctor’s instructions.

If you are elderly or physically unwell, you may need less Haldol. Your doctor may adjust your dose if necessary.

Haldol should not be used in children.

If you do not understand the instructions provided with this medicine, ask your doctor or pharmacist for help.

If you forget to use it

If you have missed your next injection, contact your doctor as soon as possible.

If you are given too much (overdose)

Immediately telephone your doctor or the Poisons Information Centre for advice, or go to Accident and Emergency at your nearest hospital. You may need urgent medical attention. Poisons Information Centre telephone numbers: Australia: 13 11 26; New Zealand: 0800 POISON or 0800 764 766. Keep these telephone numbers handy.

As this medicine will be given to you by your doctor or nurse, it is unlikely that you will be given too much.

Signs of overdose of Haldol may include severe tremor, fainting or drowsiness.

While you are given Haldol

Things you must do

Always follow your doctor’s instructions carefully.

Be sure to keep all of your doctor’s appointments so that your progress can be checked. Seek your doctor’s advice before changing or stopping Haldol treatment.

Tell your doctor if you become pregnant while using Haldol.

If you are about to start taking a new medicine, tell your doctor and pharmacist that you are being given Haldol.

Things you must not do

Do not use Haldol to treat any other complaint unless your doctor says so.

Do not give this medicine to anyone else, even if their symptoms seem similar to yours.

Schedule of Haldol Injection

Haldol Decanoate is an S4 – prescription medicine.

Side effects of Haldol Injection

All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical treatment if you get some side effects. Do not be alarmed by this list of possible side effects. You may not experience any of them.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor if you experience any of the following:

  • Drowsiness or sleepiness;
  • Restlessness;
  • Constipation;
  • Increased salivation;
  • Nausea or vomiting;
  • Changes in sex drive in both men and women;
  • Weight gain;
  • Muscle rigidity or weakness;
  • Redness, burning or pain at the site Haldol is given;
  • Blurred vision;
  • Low blood pressure which may cause dizziness or headache;
  • Shaking or tremors;
  • Uncontrollable twitching or jerking movements of the arms and legs; worm-like movements of the tongue or other uncontrolled movements of the mouth, tongue, cheeks or jaws which may progress to the arms and legs;
  • Uncontrollable muscle spasms affecting the eyes, head, neck and body;
  • Disease of the brain affecting movement, resulting in trembling, rigid posture, slow movements and a shuffling, unbalanced walk (parkinsonism).

Tell your doctor immediately if you notice any of the following as you may need urgent medical care:

  • Difficulty in breathing, or deeper and faster breathing;
  • Allergic reactions to signs such as skin rash, itching, shortness of breath, and/or swelling of the face, lips or throat that may lead to difficulty breathing or swallowing;
  • A sudden increase in body temperature, extremely high blood pressure, stiff muscles, decreased mental alertness or fits (seizures);
  • Fast or unusual heartbeat.

Other side effects not listed above may also occur in some people. Tell your doctor if you notice any other effects.

For further information talk to your doctor.


  1. Haldol Injection Consumer Medicine Information (CMI). Macquarie Park, NSW: Janssen-Cilag Pty Ltd. March 2016. [PDF]
  2. Haldol Injection Product Information (PI). Macquarie Park, NSW: Janssen-Cilag Pty Ltd. September 2017. [PDF]

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Posted On: 22 July, 2003
Modified On: 10 April, 2018
Reviewed On: 10 April, 2018


Created by: myVMC