Common causes of soft bowel movements or diarrhea include viruses, food poisoning and food allergies. Certain medications and alcohol abuse may also be the culprit, according to WebMD.
A stomach virus, also known as a stomach bug or stomach flu, is the most common cause of bowel issues, says WebMD. The symptoms of a virus typically resolve themselves within a few days, but anti-diarrhea medicine is a suitable treatment in the meantime.
Other possible causes of soft bowel movements include intestinal diseases such as Crohn's disease, hypothyroidism, some cancers and diabetes. Competitive runners also often suffer from soft bowel movements, according to WebMD.
Individuals suffering from soft bowel movements should contact their doctors, especially if the soft stool is accompanied by blood or a high fever, advises WebMD.