Loperamide is a μ-opioid receptor (μOR) agonist that exhibits gastrointestinal motility modulating, anorexigenic, analgesic, and antinociceptive activities; it also potentially inhibits HCN channels. Loperamide is clinically used as an anti-diarrheal drug as it increases gastric emptying and decreases bowel water content. Loperamide also alters pain thresholds in animal models as measured by the Hargreaves paw withdrawal apparatus. Additionally, loperamide decreases foraging behavior and body weight in vivo. Loperamide also acts as a functional inhibitor of acid sphingomyelinase (FIASMA).