Senna belongs to a kind of laxative, between 3-6 hours to take the effect, the specific time will still vary from person to person, it is not recommended to rely on senna to treat constipation and help excretion. Senna is a stimulant drug, particularly potent, if often use senna for constipation treatment, may form a dependence on the drug, insomnia, anxiety, anorexia, not often take senna orally. Senna takes effect slowly and can be taken at night before going to bed to have a bowel movement early the next morning. It is best to drink a glass of honey water on an empty stomach in the morning before defecation, which is very helpful in lubricating the intestines, promoting digestion, improving constipation and promoting bowel movements.