Trihexyphenidyl, commonly known as Artane, is a prescription-only medication used to treat symptoms associated with Parkinson's disease. Use this medication only as prescribed to reduce unwanted side effects and adverse reactions.

Trihexyphenidyl brand names

Trihexyphenidyl is available under the following brand names [5] [6]:

  • Artane
  • Tremin
  • Trihexane
  • Tritane

What is trihexyphenidyl prescribed for?

Trihexyphenidyl is approved by the U.S. Food and Drug Administration (FDA) for treating the nervous system disorder Parkinson's disease [1]

Parkinson's disease symptoms include involuntary movement, lack of muscle control, balance problems, and tremors. Trihexyphenidyl reduces tremors and muscle spasms associated with this disease [1].

This medication is often used with levodopa or other antiparkinson medications. It is not considered a front-line medical treatment. 

Doctors may also prescribe this medication as an alternative option for treating other disorders through off-label use. Off-label use of a pharmaceutical drug means the FDA has not approved it to treat the condition it is being used for. 

Off-label uses of trihexyphenidyl include:

  • Tardive dyskinesia
  • Other muscular conditions caused by central nervous system drugs 

Tardive dyskinesia is a side effect of long-term antipsychotic medication use or neuroleptic treatments.  

Some people find that trihexyphenidyl alleviates tardive dyskinesia symptoms caused by chronic neuroleptic treatments. However, tardive dyskinesia caused by antipsychotic drug use may be exacerbated by trihexyphenidyl use [2].

How does trihexyphenidyl work?

Trihexyphenidyl is an antimuscarinic drug that relaxes the muscles throughout the body [6]. Further research is needed to understand how and why this medication works.

The general consensus amongst experts is that trihexyphenidyl causes inhibited nerve impulses controlling muscle functioning through its effects on certain neurochemical receptors in the brain [1].

How is trihexyphenidyl usually taken?

Trihexyphenidyl is taken orally as a tablet or liquid solution. It can be taken with or without food. 

This medicine is only available by prescription. Take it exactly as prescribed by your doctor or healthcare provider. 

Do not tamper with tablets or alter them by cutting or crushing them unless directed to do so by your doctor. Use the supplied measuring device for accurate dosing if taking the oral solution. 

Trihexyphenidyl may be prescribed up to four times daily. Take this medication around the same time(s) each day [6].

Take missed doses as soon as possible unless it is almost time for the next dose. Do not take two doses of trihexyphenidyl at one time.

Your doctor will gradually increase the dose when first starting trihexyphenidyl to monitor for therapeutic dosage and avoid unnecessary side effects. 

Do not stop taking trihexyphenidyl without consulting with your doctor. Suddenly stopping this medicine may cause a worsening of Parkinson's symptoms [1].

How long does trihexyphenidyl stay in your system?

Trihexyphenidyl has a half-life of slightly over 3 hours, meaning the body metabolizes and expels the drug from the system within 6 hours [2]

Traces of this medication may remain detectable in the system for up to 10 days. Hair follicle testing may detect the drug for longer than other substance screenings.

Trihexyphenidyl side effects

As with any prescription medicine, trihexyphenidyl may cause side effects. Studies have found 30-50% of participants taking this medication experience at least one side effect [2]

Some side effects are more serious than others and may require changes to the prescription. Report any adverse effects experienced to your doctor for medical advice on how to continue.

Side effects from trihexyphenidyl are more likely with higher dosages.

Common side effects of trihexyphenidyl include [2]:

  • Dry mouth
  • Blurred vision
  • Dizziness
  • Muscle weakness
  • Nausea
  • Drowsiness
  • Nervousness 

Other reported trihexyphenidyl side effects include [2]:

  • Constipation
  • Irregular heart rate
  • Pupil dilation
  • Urine retention
  • Intraocular tension
  • Vomiting
  • Headaches 

Rare side effects of trihexyphenidyl have included hallucinations, agitation, confusion, delirium, delusions, and depersonalization. If any sudden changes in mental state or cognitive function occur, notify your doctor immediately [2].

Some people experience a reduced ability to sweat while taking this medication. Avoid prolonged exposure to the sun or exercising during hot weather until its effects are known [1]

Side effects may decrease over time as the body adjusts to the medication and builds tolerance. The dosage of this medication may require adjustments while taking it due to tolerance development [1].

An allergic reaction to trihexyphenidyl is unlikely but may occur. If an allergic reaction develops after taking this medicine, seek immediate medical attention. 

Signs of an allergic reaction include:

  • Hives or a skin rash
  • Swelling in the hands, mouth, lips, or extremities
  • Fever
  • Difficulty breathing 
  • Throat constricting
  • Irregular heart rate

Trihexyphenidyl precautions

Trihexyphenidyl may cause an adverse reaction when taken by people with certain preexisting medical conditions, or who are taking other medications that interact with the drug.

Discuss with your doctor all medications currently being taken, including over-the-counter medicines, medical history, and family medical history before taking trihexyphenidyl.

People with the following conditions may not be suitable for trihexyphenidyl or may need more frequent monitoring while taking it [6]:

  • Glaucoma
  • High blood pressure
  • Kidney, bladder, or liver diseases
  • Gastrointestinal diseases
  • Heart conditions
  • Prostate enlargement

Trihexyphenidyl may not be the safest or most effective medication for those aged 65 years or older [6]. Discuss with your doctor alternative medications that may be used.

Trihexyphenidyl may affect breast milk in women who are breastfeeding. Speak with your doctor about whether trihexyphenidyl is safe for use while breastfeeding or if planning to breastfeed [5].

Trihexyphenidyl may not be safe for use during pregnancy. Discuss with your doctor if pregnancy occurs while taking this medicine.

Do not suddenly stop taking this medication without first consulting with your doctor. Doing so may cause an exacerbation of Parkinson's symptoms.

Your doctor may recommend an eye exam before prescribing trihexyphenidyl to reduce the risk of glaucoma [5]. Symptoms of glaucoma include eye pain, blurred vision or tunnel vision, or a sudden or gradual loss of vision. Notify your doctor immediately if any vision changes occur while taking this medicine.

Speak with your doctor if dry mouth occurs for longer than two weeks. Continued dry mouth may lead to tooth decay or other dental complications [5].

Trihexyphenidyl interactions

Trihexyphenidyl may adversely react with certain other medications. Your doctor must know all the prescriptions currently being taken, including over-the-counter medicines and vitamin or herbal supplements.

Potassium or potassium citrate may not be recommended for use with trihexyphenidyl [5].

Avoid using this drug with other medications that cause drowsiness such as tranquilizers. Doing so may worsen the effect. 

Avoid drinking alcohol while taking trihexyphenidyl due to its sedating effects.  

Speak with your doctor about the safety of taking trihexyphenidyl with medications used for the following [4]:

  • Depression
  • Anxiety
  • Psychosis 
  • Colds
  • Allergies
  • Other Parkinson's medicines
  • Motion sickness 
  • Irritable bowel syndrome 
  • Overactive bladder 
  • Asthma 

Additionally, the following medications have been reported to have drug interactions with trihexyphenidyl [3]:

If any drug known to interact with trihexyphenidyl is being taken, your doctor may request more frequent follow-ups or additional medical testing to monitor for any negative reactions. They may also prescribe an alternative medication.

Trihexyphenidyl storage

Trihexyphenidyl should be kept in a tightly closed container away from moisture. This medication should be kept at room temperature and away from direct light sources [6].

Keep all prescription medications stored safely away from the reach of children and pets to prevent accidental ingestion. Remember, most daily pill containers are not child safe.

There is a risk of dependence with trihexyphenidyl as it is known to cause an initial euphoric feeling. There have been reports of Iraqi soldiers misusing this medication as a substitute for LSD [1]

Prevent prescription drug misuse amongst teenagers by storing trihexyphenidyl, and all prescription medications, where teens cannot access them. 

Do not share trihexyphenidyl with anyone else. 

Speak with a pharmacist or medical professional about proper ways of disposing of unused trihexyphenidyl. Avoid flushing this medication down the toilet or putting it in household garbage.

What to do if you overdose on trihexyphenidyl

An overdose of trihexyphenidyl can be fatal. Find emergency medical care if an overdose has occurred or is suspected. 

Symptoms of a trihexyphenidyl overdose are [1]:

  • Irregular heart rate
  • Nausea
  • Vomiting
  • Rash
  • Hyperthermia
  • Confusion
  • Restlessness and/or agitation
  • Incoordination
  • Paranoid thinking or psychosis
  • Delirium
  • Coma or loss of consciousness 

The poison control helpline at 1-800-222-1222 can provide additional information on what to do in case of an overdose of trihexyphenidyl. 

FAQ

How long does it take trihexyphenidyl to work?

Trihexyphenidyl is a fast-acting medication with notable changes occurring within 1 hour of the initial dose. These effects peak after 2-3 hours of taking it. 

Trihexyphenidyl's effects can last up to 12 hours. Tolerance is more likely to develop the longer the medication is used and may require an adjustment to the dosage by the physician for continued clinical results. 

Resources:

  1. Jilani TN, Sabir S, Sharma S. Trihexyphenidyl. [Updated 2022 Feb 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519488/
  2. National Center for Biotechnology Information (2022). PubChem Compound Summary for CID 5572, Trihexyphenidyl. Retrieved November 7, 2022 from  https://pubchem.ncbi.nlm.nih.gov/compound/Trihexyphenidyl.
  3. Trihexyphenidyl Interactions. (n.d.). Drugs.com. https://www.drugs.com/drug-interactions/trihexyphenidyl.html
  4. Trihexyphenidyl. (n.d.). Drugs.com. https://www.drugs.com/mtm/trihexyphenidyl.html
  5. Trihexyphenidyl (Oral Route). (2022, November 3). Â. https://www.mayoclinic.org/drugs-supplements/trihexyphenidyl-oral-route/description/drg-20072660
  6. Trihexyphenidyl: MedlinePlus Drug Information. (n.d.). https://medlineplus.gov/druginfo/meds/a682160.html