Table 1.

Characteristics of included trials.

Study ID	Sample size	Diagnosis standard	Intervention	Control	Course (week)	Outcome measure
Yang et al., 2000	230	1999 WHO -ISH GMH	EIH (SLCT)	felodipine sustained release tablet	2	BP; side effect
Hui and Shu, 2002	63	1978 WHO -ISH GMH	EIH (SLCT)	captopril	4	BP; LVH; no side effect
Liu, 2002	101	CGPMHBP-2000	EIH (SLCT)	amlodipine	4	BP; no side effect
Tang et al., 2004	80	JNC-VI	EIH (SLCT)	nitrendipine	2	BP; no side effect
Yang, 2006	52	JNC-VI	EIH (SLCT)	captopril	4	BP; LVH; no side effect
Su and Guo, 2015	166	CGPMHBP-2000	EIH (SLCC)	nifedipine	12	BP; side effect

WHO -ISH GMH, WHO -ISH guidelines for the management of hypertension; CGPMHBP, China Guidelines on Prevention and Management of High Blood Pressure; JNC-VI, Sixth Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure; BP, blood pressure; LVH, left ventricular hypertrophy; EIH, extract of I. hainanensis; SLCT, shan_lv_cha antihypertensive tablet; SLCC, shan_lv_cha antihypertensive capsule. The dosage of EIH varied from 6 to 8 tablets (1.5 to 2 g) per day divided into three times, with an average dose of about 7 tablets (1.75 g) daily.