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Uses

What is trihexyphenidyl used for?

Trihexyphenidyl is commonly used to manage symptoms caused by Parkinson’s disease, a condition that affects part of your brain that controls your movement. It may also be used to treat involuntary movements that may occur as a side effect of some medicines.

Trihexyphenidyl may also be used for other conditions as determined by your healthcare provider.

How does trihexyphenidyl work (mechanism of action)?

Trihexyphenidyl works by slowing down the activity of the parasympathetic nervous system, which controls certain automatic functions in your body, like digestion and breathing. It also helps relax muscles in your body. 

How is trihexyphenidyl supplied (dosage forms)?

Brands and other names

  • Artane

Dosage forms and strengths

  • 2 mg/5 mL oral solution
  • 2 mg, 5 mg oral tablets

How should I store trihexyphenidyl?

Oral Tablet. Trihexyphenidyl tablets should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Oral Liquid. Trihexyphenidyl liquid should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Do not freeze.

Side Effects

What are the most common side effects of trihexyphenidyl?

The most common side effects of trihexyphenidyl are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Dry mouth
  • Blurred vision or dilated pupils
  • Dizziness or drowsiness
  • Nausea, vomiting, or constipation
  • Confusion or nervousness
  • Fast heartbeat
  • Problems peeing
  • Feeling unusually weak or tired
  • Headache

There may be other side effects of trihexyphenidyl that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of trihexyphenidyl?

While less common, the most serious side effects of trihexyphenidyl are described below, along with what to do if they happen.

Severe Allergic Reactions. Trihexyphenidyl may cause allergic reactions, which can be serious. Stop taking trihexyphenidyl and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Body Temperature Regulation. Trihexyphenidyl can affect your ability to regulate your body temperature. This could make you become very hot, especially in hot weather or after exercising a lot. You should drink water and avoid overheating and dehydration. Call your healthcare provider right away if you are severely ill and have the following symptoms.

  • Excessive or no sweating
  • Dry mouth
  • Feeling very hot
  • Feeling thirsty
  • Not able to pee

Neuroleptic Malignant Syndrome (NMS). Trihexyphenidyl can cause a rare but serious condition called neuroleptic malignant syndrome. NMS is a serious condition that can lead to death. Stop taking trihexyphenidyl and call your healthcare provider right away if you have any of the following symptoms.

  • High fever
  • Muscle stiffness or rigidity, where it is hard to move
  • Changes in your breathing or heart rate
  • Increased sweating
  • Confusion

Salivary Gland Infection. Trihexyphenidyl can cause an infection in your salivary gland, a condition known as suppurative parotitis. When the mouth becomes too dry, it can lead to a decrease in saliva flow and creates an environment where bacteria can grow. Contact your healthcare provider if you notice any of the following symptoms of infection.

  • Swelling or pain on the inside of the cheek
  • Foul taste in mouth
  • Fever or chills 
  • Problems chewing or swallowing 

Slowed Gut Movement. Trihexyphenidyl may cause paralytic ileus, which is a type of ileus where your intestines are unable to move food through them. Call your healthcare provider right away if you have any of the following severe symptoms.

  • Nausea or vomiting
  • Stomach pain or bloating
  • Feeling full after eating a small portion of food
  • Problems pooping or passing gas
  • Poop that is black or looks like tar
  • Blood in your stool (poop)

Hallucinations or Psychotic-like Behaviors. Trihexyphenidyl may cause hallucinations or psychotic-like behaviors. Tell your healthcare provider right away if you have any of the following symptoms, or if you have been told by others you have these symptoms.

  • Hearing, seeing, smelling, tasting, or otherwise perceiving things that others do not
  • Delusional thoughts, such as false beliefs that you are being controlled
  • Disorganized thoughts, such as jumping between topics or having a hard time focusing
  • Sudden decline in self-care, such as personal hygiene or academic/work performance
  • Aggressive behavior

Risk of Misuse. Misusing trihexyphenidyl can lead to serious side effects like coma or death. Misuse means taking a medicine in a way other than how it was prescribed. Take trihexyphenidyl exactly as prescribed. Call your healthcare provider right away or go to the nearest emergency room if you have any of the following serious symptoms.

  • Sudden confusion or feeling disoriented
  • Feeling paranoid
  • Feelings of intense happiness, pleasure, and well being
  • Seizures
  • Changes in your heart rate or rhythm, such as a fast, slow, pounding or skipping heartbeat
  • Trouble breathing

Warnings & Precautions

Who should not use trihexyphenidyl?

Allergies to Ingredients. People who are allergic to any of the following should not take trihexyphenidyl.

  • Trihexyphenidyl
  • Artane
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific trihexyphenidyl products they stock.

Glaucoma. Glaucoma is a condition that may lead to trouble seeing or blindness because of damage to the optic nerve in your eye. Trihexyphenidyl may increase pressure inside the eye and worsen narrow-angle glaucoma. 

What should I know about trihexyphenidyl before using it?

Do not take trihexyphenidyl unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share trihexyphenidyl with other people, even if they have the same condition as you. It may harm them.

Keep trihexyphenidyl out of the reach of children.

Use an accurate measuring device to measure your dose of liquid trihexyphenidyl. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist to recommend an appropriate measuring device.

Your health care provider may have you take trihexyphenidyl before or after you eat, depending on how you react to the medicine. Taking trihexyphenidyl with food may help reduce some side effects.

Do not stop taking your other medicines for Parkinson’s disease when you start trihexyphenidyl unless your health care provider tells you to do so. Trihexyphenidyl is a medicine that is usually added to your current medicines.

Trihexyphenidyl can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how trihexyphenidyl affects you.

People who are 60 or older can be at greater risk for some side effects from trihexyphenidyl. Talk to your healthcare provider about your risks if you are in this age group.

It is important to keep all of your healthcare appointments while you are taking trihexyphenidyl, including eye appointments. These appointments help your healthcare provider know if the medicine is causing eye problems.

 If you need to stop taking trihexyphenidyl, talk to your healthcare provider first. They will give you instructions on the best way to stop the medicine so that your body can adjust, helping to reduce any uncomfortable symptoms. 

What should I tell my healthcare provider before using trihexyphenidyl?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if trihexyphenidyl is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Heart, liver, or kidney problems
  • High blood pressure
  • Stomach or bowel problems 
  • Bladder or prostate problems
  • Uncontrolled movements called tardive dyskinesia (TD)

Other Medicines and Supplements. Trihexyphenidyl may interact with other medicines and supplements. Before taking trihexyphenidyl, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how trihexyphenidyl could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take trihexyphenidyl while you are pregnant or trying to get pregnant.

Breastfeeding. It is not known if trihexyphenidyl passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should stop breastfeeding or stop trihexyphenidyl.

Interactions

Does trihexyphenidyl interact with foods or drinks?

There are no known interactions between trihexyphenidyl and foods or non-alcoholic drinks.

Do not drink alcohol. The risk of drowsiness and dizziness may be increased if you drink alcohol while taking trihexyphenidyl.

Does trihexyphenidyl interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

 In particular, make sure that you discuss if you are using any of the following before taking trihexyphenidyl.

  • A cannabinoid, such as tetrahydrocannabinol (THC) or cannabidiol (CBD), which can be found in marijuana, some prescription medicines, and other products
  • A barbiturate, such as phenobarbital, butalbital, or primidone, which is a medicine that may be used to treat insomnia, migraines, or seizures
  • An opioid, such as oxycodone, morphine, codeine, or fentanyl, which is a medicine used for certain types of pain
  • A monoamine oxidase inhibitor (MAOI), which is a medicine usually used for depression or Parkinson’s disease
  • A tricyclic antidepressant, such as amitriptyline, nortriptyline, or protriptyline, even if it is not used for depression
  • Any other medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, and medicines for anxiety

This may not be a complete list of medicines that can interact with trihexyphenidyl. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much trihexyphenidyl?

If you or someone else has used too much trihexyphenidyl, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of trihexyphenidyl?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.