Haloperidol belongs to the class of medications called antipsychotics. Haloperidol works by blocking a chemical, called dopamine, in the brain to decrease symptoms of psychosis. Haloperidol is used to manage acute and chronic psychosis and psychiatric disorders, including schizophrenia and manic states. It can also be used for the management of agitated behaviour in some people and can control verbal outbursts for people with Tourette's syndrome.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

For adults with psychosis or Tourette's syndrome, the usual starting dose of oral (taken by mouth) haloperidol ranges from 2 mg to 6 mg per day in 1 to 2 divided doses. Your doctor may gradually increase the dose to determine the most appropriate dose for you. Dosing depends on your age and needs and how well you tolerate the medication.

Seniors may require a lower starting dose, usually 0.25 mg to 0.5 mg taken 2 or 3 times a day.

For children 6 to 12 years old, the usual starting dose of oral haloperidol ranges from 0.25 mg to 0.5 mg taken 2 to 3 times a day. The doctor may recommend gradually increasing the dose and will determine the most appropriate dose. Dosing depends on how well the medication works for the child and how well it is tolerated. Haloperidol tablets should be taken with food or milk to avoid stomach upset.

Intramuscular injections of haloperidol can also be given to people with an acute psychotic attack or who are agitated or aggressive. For the ongoing treatment of psychiatric disorders, long-acting haloperidol injections are used to help decrease the number of pills some people have to take. The starting dose of the injection depends on the dose of oral haloperidol the person was previously taking. The long-acting injection is given intramuscularly (into a muscle), usually by a doctor or nurse, every 4 weeks. For some people who start using the long-acting injection, they may be taking both the oral and injection forms of haloperidol at the same time.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. Do not stop using the medication because you feel better. If you miss a dose, administer it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not administer a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect from light and moisture, and keep it out of the reach of children.

5 mg/mL injection
Each 1 mL amber vial contains haloperidol 5 mg, lactic acid sufficient to adjust the pH within the range of 3.0 to 3.8, and water for injection USP.

Do not use this medication if you:

• are allergic to haloperidol or any ingredients of the medication
• have a decreased level of consciousness, including those caused by using alcohol or other sedating medications, or coma
• have a history of spastic disease, lesions of the basal ganglia, or Parkinson's disease
• have a tumour of the adrenal gland (pheochromocytoma)
• have a severe heart or blood vessel disorder
• have severe kidney problems
• have brain damage
• have liver disease
• have a blood cell disorder (anemia, low white blood cell counts, low platelets)
• are going to receive anesthesia through the spine or for a specific region of the body

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• breast enlargement and discomfort
• changes in menstrual periods
• changed interest in sexual activity
• constipation
• dizziness, especially when getting up from a sitting or lying position
• drowsiness
• dry mouth or excessive drooling
• headache
• increased or decreased sweating
• nasal congestion
• nausea
• unusual secretion of breast milk
• vomiting
• weight changes

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• difficulty urinating or increased need to urinate
• having a feeling of internal restlessness
• heart palpitations or a racing heart
• increased blood pressure
• new or worsening constipation
• Parkinson-like symptoms such as tremor, rigidity, slowing of movement
• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg) or lungs (difficulty breathing, sharp chest pain that is worst when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of an upper respiratory tract infection such as a cold (e.g., sudden lack of energy, fever, cough, sore throat)
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• symptoms of tardive dyskinesia: rhythmical involuntary movements of the tongue, face, mouth, or jaw (e.g., protrusion of tongue, puffing of cheeks, puckering of mouth, chewing movements)
• vision changes

Stop taking the medication and seek immediate medical attention if any of the following occur:

• priapism (painful, persistent erection of the penis that is not relieved by sexual activity)
• seizures
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• sudden onset of sustained, often painful muscle spasms; can involve the neck, tongue, jaw, eyes (eyes roll back and neck arches), or body (body arches)
• symptoms of neuroleptic malignant syndrome, a potentially fatal syndrome characterized by muscle rigidity, fever, labile blood pressure, and fluctuating levels of consciousness

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Body temperature: This medication, like other antipsychotic medications, can disrupt the body's ability to control body temperature. People who exercise vigorously, who are exposed to extreme heat, are dehydrated, or are taking anticholinergic medications (e.g., benztropine, oxybutynin) are more at risk. Contact your doctor as soon as possible if you feel very hot and are unable to cool down.

Blood clots: Haloperidol has been associated with blood clots in the legs and lungs. If you experience unusual pain, heat, or swelling in one leg or sudden difficulty breathing and chest pain, get immediate medical help.

Blood counts: This medication can decrease the number of neutrophils (a type of white blood cell that helps fight infection), red blood cells (which carry oxygen), and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat) or unusual bleeding or bruising, contact your doctor immediately.

Blood sugar: Haloperidol may cause an increase in blood sugar levels (may cause a loss of blood glucose control) and glucose tolerance may change. This may happen to people who have never had high blood glucose levels. People with diabetes may find it necessary to monitor their blood sugar more frequently while using this medication.

If you have diabetes or are at risk for developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Cardiovascular effects: Cases of sudden death or altered heartbeats (torsade de pointes) have been reported by people receiving haloperidol, especially at higher than recommended doses of any formulation. If you have a heart condition called QT prolongation and electrolyte imbalances (especially potassium and magnesium) or are taking other medications that are associated with QT prolongation you should discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Dizziness when standing up: Haloperidol can cause dizziness, especially when standing from a sitting or lying position. If you have cardiovascular disease, diabetes, or are a senior, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed, since you may be more likely to experience this side effect.

Drowsiness/reduced alertness: Haloperidol may affect the mental or physical abilities needed to drive or operate machinery, particularly when you first start taking the medication or increase your dose. Avoid driving, operating machinery, or performing other hazardous tasks until you have determined how this medication affects you.

Hyperthyroidism: If you have uncontrolled high thyroid disease (hyperthyroidism), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: If you have decreased kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: If you have decreased liver function or liver disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Movement disorders: The use of haloperidol has been associated with a potentially irreversible movement disorder called tardive dyskinesia (TD). This syndrome involves the involuntary movements of facial muscles and the tongue. The risk of a person developing this syndrome is usually but not always linked to treatment duration and the total amount of antipsychotic medications taken.

If you develop signs and symptoms of TD during treatment with haloperidol, including sticking the tongue out, smacking the lips, pursing or puckering of lips, and blinking eyes rapidly, contact your doctor as soon as possible.

Neuroleptic malignant syndrome (NMS): Haloperidol, like other antipsychotic medications, can cause a potentially fatal syndrome known as neuroleptic malignant syndrome (NMS). If you notice the symptoms of NMS such as high fever; muscle stiffness; confusion or loss of consciousness; sweating; racing, or irregular heartbeat; or fainting; get immediate medical attention.

Prolonged erection (priapism): If an erection lasts longer than 4 hours (a rare occurrence), seek immediate medical assistance. If this condition is not treated quickly, tissue damage and permanent loss of the ability to have an erection could result.

Seizure disorders: Haloperidol may increase the frequency of seizures. If you have a seizure disorder or a history of drug- or medication-induced seizures, abnormal EEG, or head trauma, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Stopping the medication: If this medication needs to be stopped, it should be done gradually, under the supervision of your doctor. If you suddenly stop taking this medication, you may experience symptoms of withdrawal.

Take the medication exactly as prescribed by your doctor, and do not stop taking the medication without checking with your doctor first.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are breast-feeding and taking haloperidol, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for young children.

Seniors: Seniors taking this medication may be more likely to develop side effects from haloperidol, especially fatigue and a decreased ability to sense thirst. Seniors taking haloperidol should ensure that they drink enough fluids to remain hydrated.

There may be a higher risk of strokes, mental decline and deaths associated with the use of haloperidol by elderly people with dementia. Talk to your doctor about the risks and benefits of using this medication.

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.