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Trihexyphenidyl Oral Solution

Generic name: Trihexyphenidyl Oral Solution (try heks ee FEN i dill)
Drug class: Anticholinergic antiparkinson agents

Medically reviewed by Last updated on Jan 27, 2021.

Uses of Trihexyphenidyl Oral Solution:

  • 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 Oral Solution?

  • If you have an allergy to trihexyphenidyl or any other part of trihexyphenidyl oral solution.
  • If you are allergic to trihexyphenidyl oral solution; any part of trihexyphenidyl oral solution; 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 trihexyphenidyl oral solution.

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 trihexyphenidyl oral solution 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 Oral Solution?

  • Tell all of your health care providers that you take trihexyphenidyl oral solution. 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 trihexyphenidyl oral solution affects you.
  • Avoid alcohol or other drugs and natural products that slow your actions.
  • Do not stop taking trihexyphenidyl oral solution all of a sudden without calling your doctor. You may have a greater risk of side effects. If you need to stop trihexyphenidyl oral solution, 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 trihexyphenidyl oral solution. Be careful in hot weather and during physical activity.
  • If you are 60 or older, use trihexyphenidyl oral solution 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 Oral Solution) best taken?

Use trihexyphenidyl oral solution 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.
  • Measure liquid doses carefully. Use the measuring device that comes with trihexyphenidyl oral solution. If there is none, ask the pharmacist for a device to measure trihexyphenidyl oral solution.

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 Oral Solution?

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 Oral Solution?

  • Store at room temperature.
  • Do not freeze.
  • 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

  • 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 trihexyphenidyl oral solution, 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.