purgative
/ˈpɜ:gətɪv; `pəɡətɪv/ n, adj (substance, esp a medicine) that causes the bowels to empty; strong(ly) laxative 通便的; 催泻的; 泻药
This oil acts as a purgative/has a purgative effect. 这种油有催泻作用.
He was given a purgative before the operation. 他在手术前用了通便药.