Trihexyphenidyl (Benzhexol) is an anti-muscarinic muscle relaxant used as an antispasmodic drug for both movement disorder (dystonia) and for control of secretions (drooling) in children. In dystonia, Trihexyphenidyl (Benzhexol) relaxes dystonic, constantly tensed muscles and reduces dystonic movements. For secretions it reduces the amount of saliva produced in the mouth.

Trihexyphenidyl (Benzhexol) has two names and in Australia at the moment both are used on the packaging. This will change in 2023 when only Trihexyphenidyl will be shown on the bottle from the manufacturer. Trihexyphenidyl is the international name. Benzhexol is the outdated name, previously used in Australia. It is the same medicine. Trihexyphenidyl (Benzhexol) is also known by its brand name Artane. Ask your pharmacist if you have any questions.

While using this medicine – Remember

Try to give Trihexyphenidyl (Benzhexol) at about the same times each day. This will help you remember to give it every day.
Do not stop giving Trihexyphenidyl (Benzhexol) to your child suddenly as this may cause serious side effects Trihexyphenidyl (Benzhexol) should therefore only be stopped gradually, and you should talk to your doctor about how the medicine should be weaned. Your doctor will advise you how often and by how much to reduce your child’s dose
Tell your doctor if your child has dry eyes, enlarged (big) pupils, blurred vision, inability to pass urine or wee (urinary retention) or severe constipation.

Giving my child Trihexyphenidyl (Benzhexol)

Your doctor will work out the amount (the dose) that is right for your child. Trihexyphenidyl (Benzhexol) is started at a low dose, and slowly increased until a good response is seen

Trihexyphenidyl (Benzhexol) is available as:

ARTANE^®: 2 mg and 5 mg tablets, available from your local community or hospital pharmacy with a prescription.

When and how should I give Trihexyphenidyl (Benzhexol)?

Trihexyphenidyl (Benzhexol) can be given once, twice, three or four times each day depending upon your child’s age, weight and condition and your doctor will advise on how often is best for your child.

Your doctor will work out the amount (the dose) that is right for your child and it is important to follow your doctor’s instructions about how much to give.

Dosage Plan (for tablet administration)

Patient name:
UR Number:			Date of Plan:
Date of Birth:			Prescriber Name:
Use Trihexyphenidyl (Benzhexol) _______ mg tablets to make up the doses below
	Week 1 Date: __________	Week 2 Date: __________	Week 3 Date: __________	Week 4 Date: __________
Morning	____ tablets = ____ mg	____ tablets = ____ mg	____ tablets = ____ mg	____ tablets = ____ mg
Lunch	____ tablets = ____ mg	____ tablets = ____ mg	____ tablets = ____ mg	____ tablets = ____ mg
Dinner	____ tablets = ____ mg	____ tablets = ____ mg	____ tablets = ____ mg	____ tablets = ____ mg
Bedtime	____ tablets = ____ mg	____ tablets = ____ mg	____ tablets = ____ mg	____ tablets = ____ mg

Trihexyphenidyl (Benzhexol) can be given with or without food. Some people become very thirsty from this medicine. For these people, it can help to take the medicine before food.
Tablets should be swallowed with a glass of water or milk.
Tablets can be cut in half or crushed and mixed with liquid to be given via mouth or feeding tube. Do not mix with fruit juice or acidic foods. Your pharmacist can provide you with details on how to administer crushed or partial tablets.
Stopping the medication abruptly can be associated with potentially serious side effects. Trihexyphenidyl (Benzhexol) should therefore only be stopped gradually and you should talk to your doctor about how the medicine should be weaned. Your doctor will advise you how often and by how much to reduce your child’s dose.

What to do if a dose is missed or my child vomits

Never give a double dose of the medicine to catch up a missed dose. If several doses in a row are missed, contact your doctor for advice.

Give the missed dose as soon as you remember provided:

There is still at least 12 hours before the next dose is due for children taking trihexyphenidyl (benzhexol) once a day.
There is still at least eight hours before the next dose is due for children taking trihexyphenidyl (benzhexol) twice each day
There is still at least four hours before the next dose is due for children taking trihexyphenidyl (benzhexol) three or four times each day

Otherwise, skip the missed dose and give the next scheduled dose. You do not need to wake up a sleeping child to give a missed dose. Never give a double dose of the medicine to catch up a missed dose.

If your child vomits less than 30 minutes after having a dose, give them the same dose again. Otherwise wait and give the next dose as normal.

What to do if I give too much Trihexyphenidyl (Benzhexol)

If you think your child has had too much Trihexyphenidyl (Benzhexol) call the Poisons Information Centre on 13 11 26 even if your child shows no effects. In an emergency, call 000 for an Ambulance or take your child to hospital straight away. Have the medicine packaging with you, even if it is empty, as this information will be useful.

What about using other medicines with Trihexyphenidyl (Benzhexol)?

Tell your doctor or pharmacist about any other medicines or products your child takes before starting Trihexyphenidyl (Benzhexol). This includes prescription, over the counter medicines, vitamins, supplements, herbal or complementary medicines that you buy from a pharmacy, supermarket, health food shop or online.

Check with your doctor or pharmacist before starting new medicines or products in your child.

You can give your child medicines that contain paracetamol or ibuprofen (to treat pain and fever), unless your doctor has told you not to.
Trihexyphenidyl (Benzhexol) should not be taken with some other medicines that you get on prescription or over the counter. Tell your doctor and pharmacist about any other medicines your child is taking before starting Trihexyphenidyl (Benzhexol) .

Possible side effects – what other effects can occur?

Side effects you must do something about

Take your child to hospital or call 000 for an Ambulance if your child has:

Dry eyes, enlarged (big) pupils, blurred vision (if eyes become red, sore or have discharge, or your child is having difficulty seeing)
Urinary retention (passing less urine than normal or feeling that their bladder is full but can’t be emptied). If unable to pass urine when they need to, you must consult your doctor or go to the nearest Emergency Department.
Constipation (difficulty passing bowel motions, or pooing). The dose of trihexyphenidyl (benzhexol) may need to be reduced. Rare cases have been reported where intestinal muscles stop working (paralytic ileus) leading to very severe vomiting or constipation.

Other side effects you need to know about

Some side effects go away with time or after the dose has been changed. Speak to your doctor if you are worried about any of the following, or if they continue:

Dry mouth. In some situations, this may make softening food for swallowing difficult. Taking sips of water may help with this. If your child is having significant difficulties swallowing, the dose of trihexyphenidyl (benzhexol) may need to be decreased.
Dizziness and nausea may occur. Vomiting is uncommon.
Nervousness is commonly reported in adult patients. In children, this may present as increased irritability and changes in personality. Confusion, hallucination and disorientation are rarely reported side effects.
Decreased sweating may mean your child’s body temperature increases in hot weather. It is important to avoid over-heating and vigorous exercise as this may lead to heat stroke. It is important to ensure adequate fluid intake.

There may be other side effects that are not listed above. Contact your doctor if you notice anything unusual and you are concerned about your child.

General medicine advice

Only give this medicine to your child who was prescribed it. Never give it to anyone else, even if their condition appears to be the same, as this could do harm. Contact Poisons Information Centre on 13 11 26 if another person takes this medicine.

Always have valid prescriptions and enough supply of Trihexyphenidyl (Benzhexol).

Store Trihexyphenidyl (Benzhexol) in a cupboard (a cool dry place away from heat, direct sunlight and moisture), below 25 ^oC, out of sight and where children cannot reach it. Always keep medicine in the container or box that it came in. Dispose of expired medicines or medicines you no longer need to your pharmacy.

For more information

This fact sheet is about using this medicine in children and young people. Some information may be different from the manufacturer’s Consumer Medicine Information (CMI). The manufacturer’s CMI is found at NPS MedicineWise. These should be read together.

Talk to your doctor, nurse or pharmacist.

Contact us

In an emergency, always contact 000 for immediate assistance

Pharmacy Department
Level 2, Queensland Children’s Hospital
501 Stanley Street, South Brisbane 4101
t: 07 3068 1901 (9am – 5pm Mon – Fri)
(9am – 12pm Sat – Sun/public holidays)

Endorsed by Queensland Children’s Hospital Medication Safety Committee and developed by Rehabilitation Medical Team and Pharmacy Department, Queensland Children’s Hospital with input from parents and carers.

Updated: 18/1/23

Contact CHQMedicationSafety@health.qld.gov.au for sources used to create this Fact Sheet.

Disclaimer: We take great care to make sure the information in this Fact Sheet is correct, up-to-date and reflects current use in Australia. However, medicines can be used in different ways for different patients. It is important that you ask the advice of your doctor or pharmacist if you are not sure about something.

This Fact Sheet is to be used as an aid, rather than a substitute for a discussion with your doctor or pharmacist. Children’s Health Queensland Hospital and Health Service accepts no responsibility for any inaccuracies, omissions, reliance placed, or the success of any treatment regimens detailed in this Fact Sheet.