What is the major complication associated with combining SSRIs and TCAs?

When combining SSRIs (Selective Serotonin Reuptake Inhibitors) and TCAs (Tricyclic Antidepressants), serotonin syndrome is a significant risk due to the pharmacological effects of both classes of medications. Both SSRIs and TCAs increase serotonin levels in the brain, and when used together, they can lead to an excessive accumulation of serotonin, resulting in serotonin syndrome. This potentially life-threatening condition is characterized by symptoms such as agitation, confusion, rapid heart rate, dilated pupils, muscle rigidity, and can progress to severe outcomes if not recognized and treated promptly.

Understanding this risk is crucial for practitioners prescribing these medications. While the other options may present some concerns in a general context, they do not capture the unique and acute danger posed by the interaction of SSRIs and TCAs, making serotonin syndrome the primary concern when these two classes of antidepressants are used in conjunction.