 - Severe symptom of orthostatic hypotension orthostatic syncope or presyncope, especially when patients take alpha-adrenergic blocker Alfuzosin, Doxazosin, Naftopidil, Tamsulosin, Terazosin, Arotinolol, Carvedilol, Labetalol, Trazodone, typical and atypical antipsychotics; 