noun
A medicine that promotes bowel movements; synonymous with 下剤 (げざい).
See also: 下剤
便秘のときは通じ薬を飲むことがある。
When constipated, I sometimes take a laxative.
下剤 is the more common medical term for laxative; 通じ薬 is a slightly more colloquial or explanatory expression.
Compound of 通じ (つうじ, 'bowel movement') + 薬 (くすり, 'medicine'). The reading ぐすり is a rendaku form of くすり.