Why is this medicine prescribed?
Trihexyphenidyl is used along with other medications to treat the symptoms of Parkinson's disease (PD; a disorder of the nervous system that causes difficulties with movement, muscle control, and balance) and to control extrapyramidal symptoms (tremor, slurred speech) caused by certain medications. Trihexyphenidyl is in a class of medications called antimuscarinics. It works by relaxing muscles and nerve impulses that control the function of muscles.
Are there other uses for this medicine?
This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
How should this medicine be used?
Trihexyphenidyl comes as a tablet and elixir (liquid) to take by mouth. It usually is taken with or without food three or four times a day. Take trihexyphenidyl at around the same time(s) every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take trihexyphenidyl exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
Do not stop taking trihexyphenidyl suddenly without talking with your doctor, especially if you are also taking other medications. Sudden stoppage can cause symptoms of Parkinson's disease to return.
What special precautions should I follow?
Before taking trihexyphenidyl,
- tell your doctor and pharmacist if you are allergic to trihexyphenidyl, any other medications, or any of the ingredients in trihexyphenidyl preparation. Ask your doctor or pharmacist or check the package label for a list of the ingredients.
- tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: tranquilizers.
- tell your doctor if you have or have ever had glaucoma, high blood pressure, problems with your urinary system or prostate, stomach problems, or heart, kidney, or liver disease.
- tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking trihexyphenidyl, call your doctor.
- talk to your doctor about the risks and benefits of taking trihexyphenidyl if you are 65 years of age or older. Older adults should not usually take trihexyphenidyl because it is not as safe or effective as other medications that can be used to treat the same condition.
- if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking trihexyphenidyl.
What special dietary instructions should I follow?
Unless your doctor tells you otherwise, continue your normal diet.
What should I do if I forget to take a dose?
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
What should I do in case of overdose?
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help . If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.
What side effects can this medicine cause?
Trihexyphenidyl may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- dizziness or blurred vision
- dry mouth
- upset stomach
- difficulty urinating
Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:
- fast, irregular, or pounding heartbeat
- delusions or hallucinations
Trihexyphenidyl may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.
If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( http://www.fda.gov/Safety/MedWatch ) or by phone (1-800-332-1088).
What should I know about storage and disposal of this medication?
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).
It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org
Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( http://goo.gl/c4Rm4p ) for more information if you do not have access to a take-back program.
What other information should I know?
Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to trihexyphenidyl.
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.