I've noticed that when I drink Hibiscus Tea when my blood pressure is high it takes around an hour before my blood pressure is lowered after drinking the Hibiscus Tea.
Some people have said that Hibiscus Tea has lowered there blood pressure Immediately but for me it takes around an hour but it does lower the blood pressure.
For some people it may take a few days of drinking Hibiscus Tea to see a reduced blood pressure especially if the blood pressure is always high.