Common Side Effects of Antidepressants
The major classes of antidepressants available are selective serotonin reuptake Inhibitors (SSRI), tricyclic antidepressants (TCA), serotonin norepinephrine inhibitors (SNRI), dopamine reuptake inhibitors, noradrenergic and specific serotonergic antidepressants (NaSSA), and monoamine oxidase inhibitors (MAOI). All these medications seem to alter the levels of either serotonin, norepinephrine, or dopamine in various combinations within the brain. The most common side effects reported in studies were blurred vision, insomnia, fatigue, and sweating. Insomnia was more prevalent with TCA administration in comparison to SSRIs, while SSRIs resulted in greater cases of sweating and loss of appetite.
Cardiovascular side effects, tachycardia, and postural hypotension occur with TCA use. The gastrointestinal effect of dry mouth was associated with TCAs, while there was a significant link between nausea and SSRIs. In relation to neurological side effects, TCAs were associated with headaches, while SSRIs were associated with tremor.
Interestingly, patients on SSRIs also reported anxiety, agitation, and nervousness. These pro-stimulatory events were especially pronounced in those prescribed either fluoxetine or escitalopram. In one study, 52% of patients prescribed either of these two medications experienced excitatory side effects in comparison to the newer class of antidepressants such as venlafaxine. In fact, patients on SSRIs were less likely to experience sedation and headache than those on TCAs and SNRIs. Remarkably, patients taking Bupropion were even less likely to experience sedation than those taking SSRIs.
Sexual dysfunction was associated with SSRIs while urinary hesitancy was more commonly evident in those taking TCAs. The latter agents were also associated with increased liver enzymes, orthostatic hypotension, and urinary retention.
In summary, TCAs were characterized to a greater degree by dry mouth and blurred vision, while agitation and sexual dysfunction were more pronounced in SSRIs. The newer antidepressants (especially SNRIs) were associated with nausea and fatigue to a larger extent than the other two classes.
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