Description
This medicine is classified as an antipsychotic medication and is used to treat all forms of parkinsonism. This medicine may also be prescribed to control extrapyramidal disorders (except tardive dyskinesia) due to central nervous system drugs.

General Information
This information is for educational purposes only. Not every known side effect, adverse effect, or drug interaction is in this database. If you have questions about your medicines, talk to your healthcare provider.

Proper use of this medicine
Take this medicine exactly as directed by your doctor or pharmacist. This medicine should be taken continually, even if you are feeling better. Follow the directions on your prescription label. Do not take more or less of this medicine that prescribed. Do not share this medicine with other people.

If gastrointestinal upset occurs, take this medication with food.

Missed Dose
Take your next dose as soon as you remember. If it is time for your next dose, skip the missed dose and go back to your regular schedule. Do not double doses.

Storage
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture. Throw away any medication that is outdated or no longer needed.

Possible Side Effects
This medicine can cause the following potential side effects:

• blurred vision
• confusion
• constipation
• delusions
• dizziness
• drowsiness
• dry mouth
• gastrointestinal problems (colon enlargement or paralytic ileus)
• hallucinations
• headache
• increased intraocular pressure
• memory impairment
• mild nausea
• movement disorders
• nervousness
• paranoia
• pupil dilation
• rapid heartbeat
• skin rash
• urinary hesitancy or retention
• vomiting
• weakness

Warnings/Precautions

• This medication may impair mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle.


• Because of increased sedative effects, avoid the use of alcohol or other CNS depressants while taking this medication.


• This medicine may cause narrow angle glaucoma. Patients should have close monitoring of intraocular pressures. Notify your doctor if you experience blurring of vision while taking this medicine. Blindness has been reported due to aggravation of narrow angle glaucoma.


• Since this medication may increase the susceptibility to heat stroke, use this medication with caution during hot weather. Promptly report the occurrence of gastrointestinal problems, fever, or heat intolerance since paralytic ileus, hyperthermia, or heat stroke may occur.


• Abrupt treatment withdrawal may exacerbate parkinsonism or cause neuroleptic malignant syndrome (a potentially fatal symptom complex).


• Many cough-and-cold products contain ingredients that may add a drowsiness effect. Before you use cough-and-cold medications, ask your doctor or pharmacist about the safe use of those products.

Overdose
Seek medical attention immediately. For non emergencies, contact your local or regional poison control center at 1-800-222-1222.

Drug Interactions
Let your doctor know if you are taking any of the following types of medications:

• amantadine (Symmetrel)
• central nervous system (CNS) depressants (medicines that make you drowsy) such as:
• sedatives or tranquilizers
• antidepressants
• antianxiety medications
• antipsychotics
• sleep medications
• antihistamines (often found in prescription and over-the-counter cold, allergy, and sleep medicines)
• narcotic pain medications
• heart medications such as:
• quinidine
• digoxin (Lanoxin, Lanoxicaps)
• monoamine oxidase inhibitors (MAO) inhibitors
• tricyclic antidepressants

Pregnancy/Nursing
Tell your doctor if you are pregnant or planning to become pregnant. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when this medication is administered to a nursing woman. As with other anticholinergics, trihexyphenidyl may cause suppression of lactation. Therefore, trihexyphenidyl should only be used if the expected benefit to the mother outweighs the potential risk to the infant.

More Information
For more information about this medicine, talk to your healthcare provider.

Last reviewed:

On 8 Aug 2006

By John M. Grohol, Psy.D.