The investigators will follow the patients with asymptomatic severe hypertension who attend ED of King Chulalongkorn Memorial Hospital (KCMH), an urban, 1,500-bed, university-affiliated, tertiary care hospital as well as treatment strategies. A management strategy whether to start the drugs in ED with or without a period of observation or immediately after discharge without any observation depends on the treating physicians' judgment. The investigators predefined the pre-discharge BP at ED into two groups; high BP (pre-discharge SBP \< 180 mmHg) and severely high BP (pre-discharge SBP \>= 180mmHg) groups. Every eligible patient was scheduled for the internal medicine clinic for continuous care of the high blood pressure within 3-7 days after discharge. Medical records were retrieved for the follow-up BP, compliance and associated adverse events at the clinic. The investigators will make telephone follow-ups to the participants or their contact personnel in every case at 10 days after ED presentation to identify the deceased cases or those with major morbidity as well as the compliance to their medications.
