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Trihexyphenidyl Tablets

Generic name: Trihexyphenidyl Tablets [ try-heks-ee-FEN-i-dill ]
Drug class: Anticholinergic antiparkinson agents

Medically reviewed by Last updated on Sep 28, 2023.

Uses of Trihexyphenidyl Tablets:

  • It is used to treat Parkinson's disease.
  • It is used to treat side effects caused by some other drugs.

What do I need to tell my doctor BEFORE I take Trihexyphenidyl Tablets?

  • If you have an allergy to trihexyphenidyl or any other part of this medicine (trihexyphenidyl tablets).
  • If you are allergic to this medicine (trihexyphenidyl tablets); any part of this medicine (trihexyphenidyl tablets); or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you have narrow-angle glaucoma.
  • If you have a very bad muscle problem called tardive dyskinesia.

This is not a list of all drugs or health problems that interact with this medicine (trihexyphenidyl tablets).

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this medicine (trihexyphenidyl tablets) with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take Trihexyphenidyl Tablets?

  • Tell all of your health care providers that you take this medicine (trihexyphenidyl tablets). This includes your doctors, nurses, pharmacists, and dentists.
  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how this medicine (trihexyphenidyl tablets) affects you.
  • Avoid alcohol or other drugs and natural products that slow your actions.
  • Do not stop taking this medicine (trihexyphenidyl tablets) all of a sudden without calling your doctor. You may have a greater risk of side effects. If you need to stop this medicine (trihexyphenidyl tablets), you will want to slowly stop it as ordered by your doctor.
  • Loss of eyesight has happened in people with narrow-angle glaucoma. Talk with the doctor.
  • Have your eye pressure and eyesight checked as you have been told by the doctor.
  • Heat stroke has happened in people taking this medicine (trihexyphenidyl tablets). Be careful in hot weather and during physical activity.
  • If you are 60 or older, use this medicine (trihexyphenidyl tablets) with care. You could have more side effects.
  • Tell your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding. You will need to talk about the benefits and risks to you and the baby.

How is this medicine (Trihexyphenidyl Tablets) best taken?

Use this medicine (trihexyphenidyl tablets) as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Take with or without food. Take with food if it causes an upset stomach.
  • Drink lots of noncaffeine liquids unless told to drink less liquid by your doctor.

What do I do if I miss a dose?

  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Hallucinations (seeing or hearing things that are not there).
  • Feeling agitated.
  • Change in how you act.
  • Feeling confused.
  • Memory problems or loss.
  • Very upset stomach or throwing up.
  • Trouble passing urine.
  • A fast heartbeat.
  • Very bad constipation.
  • Very bad belly pain.
  • Muscle weakness.
  • Trouble controlling body movements that is new or worse.
  • Change in eyesight, eye pain, or very bad eye irritation.
  • Fever.
  • Not sweating during activities or in warm temperatures.
  • Larger pupils.
  • A very bad and sometimes deadly health problem called neuroleptic malignant syndrome (NMS) may happen. Call your doctor right away if you have any fever, muscle cramps or stiffness, dizziness, very bad headache, confusion, change in thinking, fast heartbeat, heartbeat that does not feel normal, or are sweating a lot.

What are some other side effects of Trihexyphenidyl Tablets?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Dizziness.
  • Upset stomach or throwing up.
  • Constipation.
  • Blurred eyesight.
  • Feeling sleepy.
  • Headache.
  • Dry mouth.
  • Feeling nervous and excitable.
  • Weight loss.
  • Restlessness.
  • Trouble sleeping.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at

If OVERDOSE is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out Trihexyphenidyl Tablets?

  • Store at room temperature.
  • Store in a dry place. Do not store in a bathroom.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

Consumer Information Use and Disclaimer

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about this medicine (trihexyphenidyl tablets), please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.