The invention provides a novel herbal antidiarrhoeal dosage form for the treatment of functional gastrointestinal disorders such as irritable bowel syndrome and diarrhea. The antidiarroheal herbal formulation comprises the decoction of Cissampelos pareria, Mangifera indica, Cinnamomum sp. and Buchanania lanzan with the conventional additives to form the oral dosage forms, which include syrup, tablets, capsules and powders ready for suspension.