Health Tip: Drugs That May Lead to Diarrhea Saturday 23rd May 2009: HCFI: Certain drugs are likely to aggravate the digestive tract and result in loose stools, said Dr KK Aggarwal President Heart Care Foundation of India and Director IMAAKN Sinha Institute. They include: Antibiotics, which often cause diarrhea because they kill bacteria -- even the good bacteria -- found in the intestines. Anti cancer drugs. Immune system-suppressing drugs.   Herbal teas and drugs containing senna or other substances that are natural laxatives. Too much use of a laxatives.A laxative is meant to relieve constipation.