The older tricyclic antidepressants (TCAs) were quite dangerous in overdose (one of the reasons they're so rarely used nowadays). It wasn't because of how they affected the brain, however, but because of their ability to alter cardiac conduction & cause arrhythmia. read more
Yes, most definitely. Depending on the particular medication, consequences can range from death to sedation to stroke, heart arrhythmias, Serotonin Syndrome with fever and seizures, brain damage- far from complete list here. read more
An antidepressant overdose often occurs when someone takes antidepressants in large doses, attempts self-harm, or combines them with other drugs and alcohol. 1,6 Signs and Symptoms Because there are many different types of antidepressants, overdose symptoms may vary. read more