My son (37yrs old) is suffering from ibs can you suggest any medicine?

Depends on symptoms: Irritable Bowel Syndrome (IBS) represents a spectrum of symptoms (that range from diarrhea to constipation, abdominal pain, bloating, more) as well as alteration in both function and perception of sensations from almost any part of the GI tract. First, ask him to be certain of diagnosis before seeking treatment please.

Hard to say: This is a label more than a diagnosis.If his symptoms are triggered by gluten sensitivity (celiac disease) the treatment would focus on dietary exclusion of all things gluten. Treatments must be tailored to the primary cause (diagnosis). Saying he has IBS is like saying he has a headache, the cause determines what you do to help.