Tricyclic antidepressants are a class of antidepressant drugs. They are named after the drugs' molecular structure, which contains three rings of atoms (compare tetracyclic antidepressant). The term 'tricyclic antidepressant' is sometimes abbreviated to TCA.

  1. Initial or mild symptoms include drowsiness, a dry mouth, nausea, and vomiting. More severe complications, include hypotension, cardiac rhythm disturbances, hallucinations, and seizures.
  2. Electrocardiogram (ECG) abnormalities are frequent and a wide variety of cardiac dysrhythmias can occur, the most common being sinus tachycardia and intraventricular conduction delay (QRS prolongation).
  3. Seizures and cardiac dysrhythmias are the most important life threatening complications.