The antihistamine properties of nimbidin in neem leaf extracts cause blood vessels to dilate and may be responsible for reducing blood pressure. Alcoholic extract of neem leaf (intravenous) produced a significant and immediate decrease in blood pressure, which lasted for several hours. Another neem leaf extract, sodium nimbidinate, administered to people with congestive cardiac failure acted successfully as a diuretic. Drinking a cup of neem leaf tea several times a week may promote lower blood pressure via these mechanisms.