What is the main side effect associated with tricyclic antidepressants (TCAs)?

Tricyclic antidepressants (TCAs) are known for their anticholinergic effects, which stem from their mechanism of action involving the blockade of acetylcholine receptors. These effects can lead to a variety of symptoms, including dry mouth, constipation, urinary retention, blurred vision, and cognitive disturbances. The anticholinergic properties are particularly significant because they can affect the overall tolerability of the medication, especially in certain populations, such as older adults, who may be more sensitive to these side effects.

While weight gain, increased energy, and sleep disruption can occur with TCAs, they are not considered the main or most characteristic side effect. Weight gain can result from the antihistaminergic properties of some TCAs, but it does not encompass the broad range of anticholinergic side effects that are more prominently associated with these medications. Increased energy is not typically a direct effect of TCAs, as they are primarily used for depression and may not universally increase energy levels in all patients. Sleep disruption is variable and can depend on individual patient response or specific TCA formulations, but again, it does not represent the hallmark side effects of this class.