Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

Rare

Confusion (more common in the elderly or with high doses); eye pain; skin rash

Symptoms of overdose

Clumsiness or unsteadiness; drowsiness (severe); dryness of mouth, nose, or throat (severe); fast heartbeat; hallucinations (seeing, hearing, or feeling things that are not there); mood or mental changes; seizures; shortness of breath or troubled breathing; trouble in sleeping; warmth, dryness, and flushing of skin

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

More common

Blurred vision; constipation; decreased sweating; difficult or painful urination (especially in older men); drowsiness; dryness of mouth, nose, or throat; increased sensitivity of eyes to light; nausea or vomiting

Less common or rare

Dizziness or lightheadedness when getting up from a lying or sitting position; false sense of well-being (especially in the elderly or with high doses); headache; loss of memory (especially in the elderly); muscle cramps; nervousness; numbness or weakness in hands or feet; soreness of mouth and tongue; stomach upset or pain; unusual excitement (more common with large doses of trihexyphenidyl)

After you stop using this medicine, your body may need time to adjust. The length of time this takes depends on the amount of medicine you were using and how long you used it. During this period of time check with your doctor if you notice any of the following side effects:

Anxiety; difficulty in speaking or swallowing; dizziness or lightheadedness when getting up from a lying or sitting position; fast heartbeat; loss of balance control; mask-like face; muscle spasms, especially of face, neck, and back; restlessness or desire to keep moving; shuffling walk; stiffness of arms or legs; trembling and shaking of hands and fingers; trouble in sleeping; twisting movements of body

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.