Probiotics may make certain conditions, like small intestine bacterial overgrowth (SIBO), worse. SIBO occurs when the small intestine contains excessive bacteria. (In general, the large intestine should house the biggest bacterial population in your digestive tract.) As a result, a probiotic could help bacteria flourish in the small intestine, which could exacerbate SIBO symptoms like bloating and diarrhea. Be sure to talk with your doctor before taking a probiotic, especially if you have SIBO or a condition like Crohn’s disease or irritable bowel syndrome (IBS). This content is not a substitute for professional medical advice or a diagnosis. Always consult your physician before pursuing any treatment plan.