If you read the indications and
contraindications for Lexapro , you will note that this SSRI can--rarely--cause either high OR low blood pressure, as well as many other side effects. SSRIs that are better known for causing hypertension are Buproprion (Wellbutrin, Zyban), Venlafaxine (Effexor), and Phenelzine (Nardil):
http://highbloodpressure.about.com/od/lifeafterdiagnosis/a/antidepressants.