Although you may have undergone investigation that has excluded dietary causes, you should know that several commonly ingested substances tend to loosen stools.
Caffeine is present in coffee, tea and cola drinks. Reduced caffeine intake or decaffeinated drinks may ease your diarrhea. (Beware that sudden cessation of caffeine may cause headaches, so withdraw slowly.)
Sorbitol, a common artificial sweetener in certain preserves, gum, and candy, has laxative effects and should also be avoided.
Since the ability to absorb lactose (milk sugar) may be impaired, you should avoid milk products until the diarrhea improves.
While reducing food intake may be wise in acute diarrhea, it is important to maintain nutrition if the attack lasts more than a few days.
For severe diarrhea, it may be necessary to avoid solid foods for a time, maintaining nutrition with clear fluids, that is, fluids with sugars and proteins through which light passes such as juices, consommé, and jellies. Some soft drinks and sweet juices may contain sugars that are difficult to absorb and therefore may aggravate the diarrhea. After acute infections, lactose and complex carbohydrates may be ill absorbed and should be avoided for a few days.