Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word: You need some medicine, stat! But, nobody wants to give you any medicine. You keep asking your pharmacist, Yuri, if he'll give you some medicine. He says no. You get pissed off, and you cuss yuri (くすり) out. He gives you the medicine after you cuss him out.
When I take medicine, I pinch my nose tight.
His life is loaded up with drugs.
My favorite kind of medicine is the suppository kind.