Haloperidol - Intramuscular

Haloperidol is used to treat schizophrenia (long-term mental disorder that causes changes in thoughts, feelings, and behaviour). It helps to relieve symptoms common in schizophrenia, such as distorted thinking and emotional instability.

This medicine may also be used to prevent nausea and vomiting after surgery.

Haloperidol may be used to treat other conditions as decided by your doctor.

Haloperidol injection is to be given intramuscularly (into the muscle, usually into the muscles of the upper arm, thigh or buttocks).

Your doctor or nurse will administer the injection for you.

The dose of this medicine will be decided by your doctor. Your doctor will advise you on the treatment timeframe depending on your condition and response to the medication.

It is important that you continue with the injections even when you feel well. Do not stop using Haloperidol injection suddenly as this may worsen your condition.

Ensure that you keep all appointments with your doctor so that you do not miss any doses. Your doctor also needs to regularly monitor your response to Haloperidol.

If you miss an appointment or miss an injection, alert your doctor or nurse. A replacement appointment or injection should be given as soon as possible.

Alert your doctor if you have the following conditions:

• Parkinson's disease (disorder that affects the movement of a person, causing symptoms such as tremors, muscle stiffness, slowed movement and impaired balance or walking)
• dementia with Lewy bodies (a group of symptoms affecting thinking, memory, and social abilities)
• recent heart attack
• heart rhythm disorder or congenital long QT syndrome (an inherited disease causing abnormally fast and erratic heartbeats)
• progressive supranuclear palsy (rare brain disease which affects the swallowing, balance, walking and eye movements)
• heart failure (weakness and inability of the heart to pump blood)

as Haloperidol may not be suitable for you.

Inform your doctor if you have the following conditions:

• other heart diseases
• alcohol abuse
• myasthenia gravis (muscle weakness disorder)
• thyroid problem
• epilepsy (fits or seizures)
• arteriosclerosis (hardening and thinning of the artery wall of the heart)
• phaeochromocytoma (rare tumour of the adrenal gland causing high blood pressure)
• liver disease
• kidney disease

Let your doctor know if you are pregnant or breastfeeding.

Be sure to check with your doctor or pharmacist before giving Haloperidol to a child or the elderly. Children or elderly people may be more sensitive to the side effects.

Some genetic traits can affect the efficacy of Haloperidol. Individuals who are CYP2D6 ultrarapid metabolisers may have poor response to this medicine, while those who are CYP2D6 poor metabolisers may have enhanced side effects of Haloperidol. Although not routinely done, your doctor may advise you to undergo genetic testing to check if this drug is best suited for you. If you know you have this gene type, inform your doctor.

Why is it important to keep my appointments with the doctor?

Keep your appointments with your doctor. Your doctor needs to monitor your condition and check your response to the medication regularly.

• Routine tests (e.g. ECG [test used to record the electrical activity of the heart], blood electrolyte level, liver and kidney function, complete blood count, blood sugar level) may be done while you are being treated with this medicine. Your doctor will advise you about how often you need to have these tests.
• Regular monitoring of signs of movement disorders may also be needed.

Haloperidol may cause drowsiness. If affected, do not drive or take part in any activity in which you need to be alert.

This medicine may cause your blood pressure to fall suddenly when you get up from a sitting or lying down position and you may feel giddy. To minimise this problem, stand up slowly.

Other side effects include any of the following: headache, difficulty sleeping, constipation, nausea, vomiting, blurred vision, rash, and changes in weight.

Some side effects may need immediate medical help. Alert your doctor immediately if you experience any of the following:

• unusual changes in mood or behaviour (being too depressed, agitated, or having compulsive and impulsive behaviour)
• muscle stiffness, uncontrolled muscle movements of your body or face such as sticking out of the tongue, smacking of the lips
• fever, confusion, change in thinking, excessive sweating
• chest pain, fast or irregular heartbeats
• fits or seizures
• yellowing of the skin or eyes, abdominal pain, dark coloured urine, tiredness, swelling in the legs and ankles
• pain, swelling and tenderness in your leg accompanied by redness and warmth
• difficulty passing urine

Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.

Inform your doctor and pharmacist if you are taking any of these medicines:

• certain antibiotics e.g. erythromycin, moxifloxacin
• medicines for epilepsy (fits or seizures) e.g. carbamazepine, phenobarbital
• other medicines for mood disorders e.g. lithium, pimozide
• medicines to treat depression e.g. fluoxetine, fluvoxamine
• medicines for irregular heartbeat e.g. disopyramide, quinidine, amiodarone
• rifampicin (medicine to treat TB [infection known as tuberculosis])
• medicines to treat fungal infection e.g. itraconazole, ketoconazole
• water pills or medicines for water retention
• St. John’s wort (herbal medicine)

This list does not include all medicines that may interact with Haloperidol.

Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements, and medicines that you buy without a prescription.

Avoid alcohol. Alcohol intake may worsen the dizziness and drowsiness caused by Haloperidol.

Store in a cool, dry place away from the reach of children.

Medicines must not be used past the expiry date.