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.
- Initial or mild symptoms include drowsiness, a dry mouth, nausea, and vomiting. More severe complications, include hypotension, cardiac rhythm disturbances, hallucinations, and seizures.
- 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).
- Seizures and cardiac dysrhythmias are the most important life threatening complications.