Trihexyphenidyl Patient Information

Find out why trihexyphenidyl is prescribed, side effects of trihexyphenidyl, trihexyphenidyl warnings, effects of trihexyphenidyl during pregnancy, more - in plain English.

Generic name: Trihexyphenidyl hydrochloride

Trihexyphenidyl Full Prescribing Information

Why is Trihexyphenidyl prescribed?

Trihexyphenidyl is used, in conjunction with other drugs, for the relief of certain symptoms of Parkinson's disease, a brain disorder that causes muscle tremor, stiffness, and weakness. It is also used to control certain side effects induced by antipsychotic drugs such as Thorazine and Haldol. Trihexyphenidyl works by correcting the chemical imbalance that causes Parkinson's disease.

Most important fact about Trihexyphenidyl

Trihexyphenidyl is not a cure for Parkinson's disease; it merely minimizes and reduces the frequency of symptoms such as tremors.

How should you take Trihexyphenidyl?

You may take Trihexyphenidyl either before meals or after meals, whichever you find more convenient. Your doctor will probably start you on a small amount and increase the dosage gradually. Take Trihexyphenidyl exactly as prescribed.

If the medication makes your mouth feel dry, try chewing gum, sucking mints, or simply sipping water.

Trihexyphenidyl comes in tablet and liquid form. With either, you will probably need to take 3 or 4 doses a day.

Once you have reached the dosage that is best for you, your doctor may switch you to sustained-release capsules ("Sequels") which are to be taken only once or twice a day. Do not open or crush the sequels. Always swallow them whole.

--If you miss a dose...

Take it as soon as you remember. If it is within 2 hours or your next dose, skip the one you missed and go back to your regular schedule. Do not take 2 doses at the same time.

--Storage instructions...

Store at room temperature. Do not allow the liquid to freeze.

What side effects may occur taking trihexyphenidyl?

Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Trihexyphenidyl.

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  • Common side effects of Trihexyphenidyl​​​​​​​ may include: Blurred vision, dry mouth, nausea, nervousness

These side effects, which appear in 30% to 50% of all people who take Trihexyphenidyl, tend to be mild. They may disappear as your body gets used to the drug; if they persist, your doctor may want to lower your dosage slightly.

  • Other potential side effects include: Agitation, bowel obstruction, confusion, constipation, delusions, difficulty urinating, dilated pupils, disturbed behavior, drowsiness, hallucinations, headache, pressure in the eye, rapid heartbeat, rash, vomiting, weakness

Why should Trihexyphenidyl not be prescribed?

Do not take Trihexyphenidyl if you are known to be sensitive to it or if you have ever had an allergic reaction to it or to other antiparkinson medications of this type.

Special warnings about Trihexyphenidyl 

The elderly are highly sensitive to drugs such as Trihexyphenidyl and should use it with caution.

Artane can reduce the body's ability to perspire, one of the key ways your body prevents overheating. Avoid excess sun or exercise that also cause you to become overheated.

If you have any of the following conditions, make sure your doctor knows about them, since Trihexyphenidyl could make them worse:

Enlarged prostate
Stomach/intestinal obstructive disease
Urinary tract obstructive disease

It is important to stick to the prescribed dosage; taking larger amounts "for kicks" could lead to an overdose.

Your doctor should watch you carefully if you have heart, liver, or kidney disease or high blood pressure, and should check your eyes frequently. You should also be watched for the development of any allergic reactions.

Possible food and drug interactions when taking Trihexyphenidyl

If you take Trihexyphenidyl along with any of the drugs listed below, your doctor may need to adjust the dosage of Trihexyphenidyl, the other medication, or possibly both.

Amantadine (Symmetrel)
Amitriptyline (Elavil)
Chlorpromazine (Thorazine)
Doxepin (Sinequan)
Haloperidol (Haldol)

Special information if you are pregnant or breastfeeding

No specific information is available concerning the use of Artane during pregnancy or breastfeeding. If you are pregnant or plan to become pregnant while taking Artane, inform your doctor immediately.

Recommended dosage for Trihexyphenidyl

Your doctor will individualize the dose to your needs, starting with a low dose and then increasing it gradually, especially if you are over 60 years of age.


Parkinson's Disease:

The usual starting dose, in tablet or liquid form, is 1 milligram on the first day.

After the first day, your doctor may increase the dose by 2 milligrams at intervals of 3 to 5 days, until you are taking a total of 6 to 10 milligrams a day.

Your total daily dose will depend upon what is found to be the most effective level. For many people, 6 to 10 milligrams is most effective. Some, however, may require a total daily dose of 12 to 15 milligrams.

Drug-Induced Parkinsonism:

Your doctor will have to determine by trial and error the size and frequency of the dose of Trihexyphenidyl needed to control the tremors and muscle rigidity that sometimes result from commonly used tranquilizers.

The total daily dosage usually ranges between 5 and 15 milligrams, although, in some cases, symptoms have been satisfactorily controlled on as little as 1 milligram daily.

Your doctor may start you on 1 milligram of Trihexyphenidyl a day. If your symptoms are not controlled in a few hours, he or she may slowly increase the dose until satisfactory control is achieved.

Use of Trihexyphenidyl​​​​​​​ with Levodopa:

When Trihexyphenidyl is used at the same time as levodopa, the usual dose of each may need to be reduced. Your doctor will adjust the dosages carefully, depending on the side effects and the degree of symptom control. Trihexyphenidyl dosage of 3 to 6 milligrams daily, divided into equal doses, is usually adequate.

Trihexyphenidyl​​​​​​​ tablets and Liquid:

You will be able to handle the total daily intake of Trihexyphenidyl tablets or liquid best if the medication is divided into 3 doses and taken at mealtimes. If you are taking high doses (more than 10 milligrams daily), your doctor may divide them into 4 parts, so that you take 3 doses at mealtimes and the fourth at bedtime.

Overdosage of Trihexyphenidyl

Overdosage with Artane may cause agitation, delirium, disorientation, hallucinations, or psychotic episodes.

  • Other symptoms may include: Clumsiness or unsteadiness, fast heartbeat, flushing of skin, seizures, severe drowsiness, shortness of breath or troubled breathing, trouble sleeping, unusual warmth

If you suspect an overdose of Trihexyphenidyl, seek medical attention immediately.

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Trihexyphenidyl Full Prescribing Information

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APA Reference
Staff, H. (2009, January 4). Trihexyphenidyl Patient Information, HealthyPlace. Retrieved on 2024, July 16 from

Last Updated: January 23, 2019

Medically reviewed by Harry Croft, MD

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