That's not true; I suspect it depends on how many other receptors they hit. One reason Lexapro/escitalopram is liked for its laser precision, in the prescribing information it has the following aside, relevant to receptors it doesn't hit:
"Antagonism of muscarinic, histaminergic, and adrenergic receptors has been hypothesized to be associated with various anticholinergic, sedative, and cardiovascular side effects of other psychotropic drugs."
"Antagonism of muscarinic, histaminergic, and adrenergic receptors has been hypothesized to be associated with various anticholinergic, sedative, and cardiovascular side effects of other psychotropic drugs."