Ha - lo - pe - ree - dol de - can - o - ate
Why have I been prescribed haloperidol decanoate?
Haloperidol decanoate is used to treat schizophrenia, psychosis and similar conditions.
When they have schizophrenia, many people hear voices talking to them or about them. They may also become suspicious
or paranoid. Some people also have problems with their thinking and feel that other people can read their thoughts. These
are called "positive symptoms". Haloperidol can help to relieve these symptoms. Many people with schizophrenia also
experience "negative symptoms". They feel tired and lacking in energy and may become quite inactive and withdrawn.
Haloperidol may help relieve these symptoms as well. Haloperidol is also useful to help manage agitation, anxiety, mania or
hypomania and some other conditions.
What exactly is haloperidol decanoate?
Schizophrenia and similar disorders are sometimes referred to as psychoses, hence the name given to this group of
medicines, which is the “antipsychotics”. They are sometimes also called the neuroleptics or (incorrectly) major
tranquillisers. Haloperidol decanoate is an antipsychotic. It is a depot injection that is a long-acting form of the medication.
When injected into a muscle, it creates a store or “depot” and is released slowly into the body over several weeks.
Haloperidol is the active drug. The decanoate is an inactive part that helps dissolve the flupenthixol in the oil for the
The brand or trade name of haloperidol decanoate is ‘Haldol Decanoate’.
Is haloperidol safe to have?
It is usually safe to have haloperidol depot injections regularly as prescribed by your doctor, but it doesn’t suit everyone. Let
your doctor know if any of the following apply to you, as extra care may be needed:
a) If you have epilepsy, diabetes, Parkinson’s disease or glaucoma, or suffer from heart, liver, kidney, thyroid or prostate
b) If you are taking any other medication. This includes medicines from your pharmacist, such as antihistamines;
c) If you are pregnant, breast feeding, or wish to become pregnant.
How is haloperidol given?
First of all, a test dose of haloperidol (which is a low dose) is given to see how your body copes with it. Then you will be
given regular injections. The injection is given deep into the buttock or thigh muscle. The injection can be given by a CMHN
(Community Mental Health Nurse) or by your GP’s practice nurse. The dose will depend on your symptoms and side
What is the usual dose of haloperidol decanoate?
The test dose is usually between 25mg and 50mg. The usual dose can vary from 12.5mg to 75mg a week (or up to 300mg
a month). Haloperidol injections are usually given every four weeks, but can they be given every two or three weeks.
What happens if I miss an injection?
You should contact your nurse/doctor as soon as you remember. They will probably arrange for another injection to be
given to you.
When I feel better, can I stop having my injections?
No. If you stop taking haloperidol, your original symptoms may return, but this may not be for 3 to 6 months after you stop
the drug. You and your doctor should decide together when you can come off it. Most people need to be on haloperidol for
quite a long time, sometimes years. Haloperidol is not addictive.
What will happen to me when I start haloperidol injections?
Antipsychotics do not work straight away. For example, it may take several days or even weeks for some of the symptoms
to reduce. To begin with, most people find that this medication will help them feel more relaxed and calm. Later, after one
or two weeks, other symptoms should begin to improve.
Unfortunately, you might get some side effects before you start to feel any better. Most side effects should go away after a
few weeks. Look at the table over the page. It tells you what to do if you get any of the usual side effects. Not everyone will
get the side effects shown. There are many other possible side effects. Ask your pharmacist, doctor or nurse if you are
worried about anything else that you think might be a side effect.
Side effect What is it? What should I do if it happens to me?
AKATHISIA You feel restless, unable to feel comfortable unless you
are moving.
Tell your doctor about this. It may be possible to
change your drug or dose, or give you something to
reduce these feelings.
Feeling shaky or having a tremor. Your neck may twist
back. Your eyes and tongue may move on their own.
It is not usually dangerous. If it is bad or worries you,
tell your doctor. They can give you something for it.
Prolactin is a natural chemical we all have. High levels
can affect periods in women or cause impotence in
men. It may also cause breast tenderness and milk
secretion, in men as well as women.
This sometimes wears off in a few weeks, but discuss
this with your doctor anyway. It may be that a change in
dose or different drug will help.
Dry mouth. Not much saliva or spit. Sugar-free boiled sweets, chewing gum or eating citrus
fruits usually helps. If not, your doctor can give you a
mouth spray. A change in medicine or dose may be
Blurred vision Things look fuzzy and you can’t focus properly. See
your doctor if you are worried. You won’t need glasses.
Feeling "bunged up" inside. You can't pass a motion or
Eat more fibre e.g. bran, fruit and vegetables. Do more
walking. Make sure you drink plenty of fluid. A mild
laxative from a pharmacy might help.
Difficulty in passing urine Contact your doctor now.
DROWSINESS Feeling sleepy or sluggish. Don’t drive or use machinery. As your treatment
continues you should feel less drowsy.
HYPOTENSION A low blood pressure. You may feel faint when you
stand up.
Try not to stand up too quickly. If you feel dizzy, don’t
drive. This dizziness is not dangerous
Finding it hard to have an orgasm. No desire for sex.
Men can become impotent.
Discuss this with your doctor when you next meet.
Injection site swells. It feels painful and lumpy. Report it to your nurse. Warm baths and regular
exercise like walking can help.
WEIGHT GAIN Eating more and putting on weight. Avoid fatty foods like chocolate, crisps and fizzy drinks.
A diet full of vegetables and fibre will usually help, as
will physical activities such as walking. If it becomes a
problem or you are worried, ask to see a dietician.
NMS Neuroleptic Malignant Syndrome includes a high body
temperature, muscle stiffness and being unable to
It usually occurs within a few weeks of a dose change.
Contact your doctor immediately. Keep cool, with fans
or cool water.
What about alcohol?
It is officially recommended that people taking haloperidol should not drink alcohol. This is because both haloperidol and
alcohol can cause drowsiness. If the two are taken at the same time, severe drowsiness can result. This can lead to falls or
accidents. As well as this, drinking alcohol often makes psychosis worse. Excessive drinking is especially likely to do this.
Once people are used to taking medication, they can sometimes drink alcohol in small amounts without any harm. Avoid
alcohol altogether for the first one or two months. After this, if you want a drink, try a glass of your normal drink and see
how you feel. If this doesn’t make you feel drowsy, then it is probably OK to drink small amounts. It pays to be very cautious
because alcohol affects people in different ways, especially when they are taking medication.
Don't stop taking your medication because you fancy a drink. Discuss any concerns you may have with your doctor,
pharmacist or nurse. If you do drink alcohol, drink only small amounts. Never drink any alcohol and drive.
Remember, leaflets like this can only describe some of the effects of medication. You may find other
books or leaflets also useful. If you have access to the internet you may find a lot of information
there as well, but be careful, as internet based information is not always accurate.
2001 United Kingdom Psychiatric Pharmacy Group www.ukppg.org.uk
This leaflet is to help you understand about your medicine. It is not an official manufacturer's Patient Information Leaflet.
For more information call the UKPPG National Telephone Helpline, 11am to 5pm, Monday to Friday on 020 7919 2999 or
visit www.nmhct.nhs.uk/pharmacy
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