[lyall]

Heroin, like pretty much all opioids, is actually the exact opposite of a laxative. Imodium (Loperamide), a common anti-diarrheal, is actually an opioid like heroin, and works by binding to and activating your body's opioid receptors. It just only binds to receptors in your large intestine, so it doesn't get you "high" like other opioids.