thoughtscape NP Psychiatry · Patient education
Trihexyphenidyl
Artane • historical brand name
For certain movement problems, with close attention to memory, vision, bowel function, and heat safety.
Draft for review · Clinical content has not been revalidated for this website.
mAChR means muscarinic acetylcholine receptor. Blocking it can help movement and also cause side effects.
What it is used for
Used with other treatment for Parkinson disease, or for stiffness, shaking, and slowed movement caused by some medicines.
A specialist may also use it for certain dystonias, which cause twisting or sustained muscle contractions. That use is off-label.
How it works
Blocks a messenger called acetylcholine in movement pathways. It may reduce some stiffness or shaking.
It does not help every movement problem. It can worsen tardive dyskinesia, including repeated lip-smacking or tongue movements. Report any new movements.
What to expect over time
LOW START
Your team starts with a small amount and increases gradually.
EARLY REVIEW
Some effects begin within hours. Useful improvement and side effects guide the dose.
ONGOING CHECKS
Ask whether the movement benefit still outweighs memory, eye, or bowel problems.
Taking your medication
Follow the dose schedule on your prescription. Doses are usually divided three or four times daily, not taken all at once.
Food may help an upset stomach. Ask whether taking it before or after meals suits your symptoms.
If instructed to take half a tablet, have the pharmacist confirm the tablet and demonstrate how. Do not change the dose yourself.
When to get help
Get urgent eye care: a painful red eye, sudden blurred vision, or vision loss. Do not wait for the next eye appointment.
Get emergency help: overheating with little sweating, severe confusion, or fever with marked muscle stiffness, especially after a dose change.
Seek prompt care: inability to urinate, severe belly swelling, or pain, hallucinations, or a fast or irregular heartbeat.
Early side effects
Dry mouth, constipation, nausea, dizziness, headache, and blurred vision may occur. Drowsiness can affect driving. Call if symptoms interfere with daily activities or do not improve.
Other effects to discuss
Watch for forgetfulness, confusion, falls or worsening movements. Older adults are more sensitive. Keep eye-pressure checks even if you feel well; sudden painful vision changes need urgent care.
What to keep track of
Track movement symptoms, bowel movements, urination, alertness, and vision. Your team should arrange an eye assessment before treatment and eye-pressure checks during it. Other tests depend on your health and symptoms.
Before you start
Mention glaucoma, urinary or prostate problems, severe constipation, or bowel blockage, heart-rhythm problems, high blood pressure, kidney or liver disease, memory problems, and falls. Discuss pregnancy or breastfeeding if relevant. Tell the surgery or dental team that you take it.
Medicines & interactions
Allergy, bladder, and sleep products
Some add drying, constipation, blurred vision, and confusion. Check products bought without a prescription before using them.
Mental-health and movement medicines
Some antidepressants, antipsychotics, and amantadine add side effects. Levodopa combinations may need dose changes; do not make those changes yourself.
Alcohol, opioids, and cannabis
These can worsen sleepiness or confusion. Avoid alcohol and have your prescriber review any sedating substances.
Everyday tips
Stay cool, especially during hot weather or exercise; take cooling breaks.
Use good dental care and sugar-free gum for dry mouth; drink fluids if allowed.
Ask for a constipation plan and report persistent problems.
Keep a simple dose and symptom log; ask someone you trust to notice memory changes.
Your questions, answered
What if I miss a dose?
Take it when remembered unless the next dose is near. Then skip it; never double. If several doses are missed, ask how to restart rather than catching up.
Can I stop when I feel better?
Do not stop suddenly. Your team may reduce it gradually and watch for returning movement symptoms, sweating, nausea, or sleep changes. Call about symptoms during a reduction.
Can I drive?
Do not drive when sleepy, dizzy, confused, or unable to see clearly. Wait until you know how it affects you, including after dose changes.
What if I take too much?
Call Poison Control now: 1-800-222-1222. Do not wait for symptoms or make yourself vomit. Call 911 for collapse, seizure, breathing trouble, or inability to wake up.
Storage & safety
Store tightly closed at room temperature, away from heat and moisture, out of children's and pets' reach. Do not share the medicine. Ask the pharmacist about a take-back program for unused tablets.
About this information
For general information only; not a substitute for individualized medical advice. This sheet does not cover every risk or interaction. Ask your prescriber or pharmacist before changing how you take this medication.
Sources
Educational inclusion does not mean this medication or its indications are treated at this practice. Review the guide for your exact product with your prescriber or pharmacist.