Why is my poo always runny?

Many reasons: There are many reasons why your stool can be runny. Medications and supplements that you are taking can be one. Your diet too can highly influence the consistency of your stool; if you are taking too much fiber or prunes. Less common causes would be infection and certain medical conditions which your doctor can check for.

Diarrhea or impactio: It is important to know your age and since when you have had this and if you did have constipation in the past. Is it diarrhea or is it stool impaction that only allows the fluid stool to come out. Is it recent onset or you have had it x long time? Bottom line...See a dr either pcp or gastroenterologist. You may need a colonoscopy.