くすりき 薬が効く Show inflections LinksSentence search for 薬が効くSentence search for くすりがきくKanji details for 薬 and 効Edit in JMdict Expressions (phrases, clauses, etc.), Godan verb with 'ku' ending1. to have medicine be effectiveうん運よくくすりがき薬が効くとき１じ時す過ぎにね寝れるけど、くすり薬をの飲まないと４じ時ぐらいまでねむ眠れない。If I'm lucky enough for the medicine to work I can get to sleep after 1am but if I don't take it then I can't sleep until about 4am. Discussions Log in to talk about this word.