May cause significant drowsiness and impaired alertness; avoid driving/alcohol. Use with caution in elderly, glaucoma, enlarged prostate/urinary retention, constipation, asthma/COPD, liver or kidney impairment. Can prolong QT interval and rarely cause serious heart rhythm problems—avoid in patients with known QT prolongation, significant electrolyte imbalance (low potassium/magnesium), or with other QT-prolonging medicines. Seek urgent care for palpitations, fainting, severe dizziness, or allergic reaction.
