Before taking trihexyphenidyl, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: personal or family history of glaucoma (angle-closure type), blockage of the bladder/esophagus/stomach/intestines (e.g., bowel obstruction), severe ulcerative colitis.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: breathing problems (e.g., asthma, emphysema), diarrhea caused by an infection, heart problems (e.g., angina, heart attack, heart failure, fast/irregular heartbeat), high/low blood pressure, intestinal problems (e.g., chronic constipation, ileus, ulcerative colitis), kidney disease, liver disease, mental/mood problems (e.g., anxiety, dementia, psychosis), certain muscle disease (myasthenia gravis), certain nerve disease (autonomic neuropathy), seizure, stomach problems (e.g., acid reflux, hiatal hernia, ulcer), stroke, overactive thyroid (hyperthyroidism), problems urinating (e.g., due to enlarged prostate, neurogenic bladder), personal or family history of a substance use disorder (such as overuse of or addiction to drugs/alcohol).
This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).
To minimize dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.
This medication decreases saliva production, an effect that can increase gum and tooth problems (e.g., cavities, gum disease). Take special care with your dental hygiene (e.g., brushing, flossing) and have regular dental check-ups.
Liquid forms of this product may contain alcohol. Caution is advised if you have diabetes, alcohol dependence, or liver disease. Some medications (e.g., disulfiram, metronidazole) may cause a serious reaction when combined with alcohol. Tell your doctor if you are taking any medication that should not be used with alcohol. Ask your doctor or pharmacist about using this product safely.
This drug can cause decreased sweating, which could cause a severe rise in your body temperature (hyperthermia). The risk of this serious side effect is greater in hot weather, during vigorous exercise, and/or if you drink alcohol. Drink plenty of fluids and dress lightly while in hot weather and when exercising. If you experience signs of hyperthermia such as mental/mood changes, headache, or dizziness, promptly seek cool or air-conditioned shelter and/or stop exercising, and seek immediate medical attention. Consult your doctor for more details.
Older adults may be more sensitive to the side effects of this drug, especially dizziness, drowsiness, heatstroke, memory problems, difficulty urinating, and constipation. Dizziness and drowsiness can increase the risk of falling.
Children may be more sensitive to the effects of this drug, especially effects on heart rate.
This drug should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor.
It is not known if this drug passes into breast milk. Consult your doctor before breast-feeding.