The basic principle for treatment of idiopathic diarrhea is to delay transit through the gut in order to promote absorption of electrolytes and water. Under mild conditions bulking agents may suffice. With increasing severity, antidiarrheal pharmaceuticals may be added in a stepwise manner. Bile salt malabsorption is a clear indication for adsorptive resins, while in idiopathic diarrhea peripherally-acting opioid receptor agonists, such as loperamide, is the first-line treatment. Second-line treatment with approved indication for severe diarrhea when other treatment options fail includes opium drops. More advanced treatments are to be used by clinicians with specialist knowledge and experience in the field.