This medication may cause flushing of the face, problems sleeping, headache, blurred vision, drowsiness, increased sensitivity to light, constipation, dry mouth, decreased sweating or thirst. If any of these symptoms persist or worsen, inform your doctor. Notify your doctor if you develop: confusion, tremors, rapid/irregular heartbeat, difficulty urinating. In the unlikely event you have an allergic reaction to this drug, seek immediate medical attention. Symptoms of an allergic reaction include: rash, itching, swelling, dizziness, trouble breathing. If you notice other effects not listed above, contact your doctor or pharmacist.