The present invention relates to a method for the long term treatment of gastrointestinal disorders in a human subject, which comprises administering an effective amount of a halogenated prostaglandin compound and/or its tautomer to the subject. The method induces substantially no electrolyte shifting during the term of the treatment. The compound used in the present invention can improve quality of life in the human subjects with gastrointestinal disorders, are similarly effective in treating male and female subjects, and also effective in a human subject aged even 65 years and older.
