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laxative; purgative; evacuant
便秘で下剤を飲みました。
I took a laxative for constipation.
医師は軽度の便秘に下剤を処方した。
The doctor prescribed a laxative for mild constipation.
下剤が効いて、翌朝には便秘が解消された。
The laxative worked, and my constipation was relieved by the next morning.