Milo Miller (@floridaboy920), an ex-Amish reality TV star, recently shared his four-ingredient recipe for “Amish cough syrup” on TikTok, where it’s already racked up over 889,000 views.

Lean, a combination of prescription cough syrup containing codeine and promethazine mixed with soda, has long been a dangerous staple in hip-hop culture. Many artists have struggled with its ...