Hi welcome to the health care magic First drug you have mentioned can be used in IBS to relieve constipation as it increasing chloride and water secretion so facilitate bowel movements Second drug you have mentioned is used for relieving muscle spasm if present... If spasm not present than don t use it... Behavioural modification needed in IBS as this is functional bowel problem.. Take more fiber diet like whole grain, wheat bran, Apple and fruits more.... If needed fiber supplements can be given You can consult physician for starting lubiprostone like specific drug if needs to start which is specif drug for IBS... Take care Consult physician for examination