Trihexyphenidyl is used alone or together with other medicines to treat Parkinson's disease. Parkinson's disease is a disorder that affects movement of a person, causing symptoms such as tremors, muscle stiffness, slowed movement and impaired balance or walking.
Trihexyphenidyl cannot cure Parkinson's disease but it can improve the quality of life for people who have the disease.
Trihexyphenidyl may also be used to treat other conditions, as decided by your doctor.
Take Trihexyphenidyl exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.
Take Trihexyphenidyl with food. However, you may take Trihexyphenidyl before food if you experience dry mouth; or after food if drooling occurs. Try to take Trihexyphenidyl at the same time each day.
Trihexyphenidyl must be taken regularly for it to be effective. Continue taking Trihexyphenidyl even when you feel better. Do not stop taking Trihexyphenidyl unless instructed otherwise, as stopping it suddenly could worsen your condition.
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal schedule.
DO NOT double a dose under any circumstances.
If you often forget to take your medicine, let your doctor or pharmacist know.
Alert your doctor if you have glaucoma (increased pressure in the eye) as Trihexyphenidyl may not be suitable for you.
Inform your doctor if you have the following conditions:
- kidney disease
- liver disease
- heart disease
- high blood pressure
- prostate enlargement or urinary problems
- stomach or bladder blockage
Let your doctor know if you are pregnant or breastfeeding.
As Trihexyphenidyl may cause the pressure in your eyes to increase, you will need to have regular eye examination to monitor for any changes in your eyes. Your doctor will advise you about how often you need to have these tests.
Trihexyphenidyl may cause drowsiness, tiredness and dizziness. If affected, do not drive or take part in any activity in which you need to be alert.
Dry mouth is a common side effect of Trihexyphenidyl. If you experience severe dry mouth, take some sweets, mints or chewing gum to help reduce the discomfort.
Other side effects include any of the following: vomiting, nausea, stomach pain, constipation, urinary difficulties, headache and blurred vision. These side effects are common especially when you have just started taking Trihexyphenidyl.
Trihexyphenidyl reduces the ability of your body to sweat. Avoid prolonged exposure to sunlight or exercise which may cause your body to overheat as you are not able to sweat.
Let your doctor know if you experience:
- confusion and hallucinations (seeing, hearing or feeling things that are not existent)
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Inform your doctor and pharmacist if you are taking any of these medicines:
- medicines for mood disorder or depression e.g. chlorpromazine, doxepin, barbiturates
- medicine for nausea or vomiting e.g. metoclopromide
- medicine for cold or allergy e.g. chlorpheniramine
- other medicines for Parkinson's disease e.g. amantadine, levodopa
- Alzheimer's disease medicine e.g. memantine
This list does not include all medicines that may interact with Trihexyphenidyl.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicine, supplements and medicines that you buy without a prescription.
Avoid alcohol, citrus foods and coffee.
Store in a cool, dry place away from the reach of children.
Medicines must not be used past the expiry date.