Hello, Inderal may cause diarrhea, even thought this is not a very common side effect. It is important to talk to your doctor related to the possibility of the diarrhea being due to it and possible medications you can use to substitute it. On the other hand there are other causes of chronic diarrhea as well that are related to the problems with the pancreas, bowel or even food intolerances and other conditions that the doctor might need to also consider and rule out. Meanwhile you need to drink plenty, take oral rehydration solutions to help substitute the lost electrolytes as well and avoid fat and sweet food, avoid junk food, avoid caffeine and alcohol. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Antoneta Zotaj, General & Family Physician