Senna
Cassia angustifolia
“Senna is a reliable and quite powerful laxative. Small doses of 1-2g will result in pultaceous stools being produced within 5-7 hours. Higher doses of 2-4g will act more rapidly, but the stools will then often be liquid and accompanied with abdominal pain. The side effects are even more marked if the dose is increased to 8-12g, when severe colic, nausea and vomiting may develop.
“Senna pods have a gentler action than the leaves, although they contain a higher concentration of sennosides. This is probably due to other, as yet unknown, constituents.
“The fact that senna leaves are not well tolerated in large doses is largely due to the resins they contain. Senna leaf tea should therefore always be made with cold water, leaving it to stand for some time, so that it is a maceration rather than a tea, and the resins do not go into solution to any extent.
“Removal of the resin reduces the colic-inducing effect of senna leaves. On the other hand the laxative action is also reduced. Deresinated senna leaves will often be very useful for highly irritable bowels. The price is a little higher than for ordinary senna leaves.”
- Herbal Medicine