One of the side effects of cephalexin is it can cause pseudomembranous colitis. if you were to give a percentage, how likely is this to happen?

Cannot: Clostridium difficile colitis occurs when you alter the normal colonic flora with antibiotics and it grows out and produces toxin. Whether this happens depends on whether you were previously colonized with this organism, the strain in your colon and other factors. No specific %s are available. Don't use antibiotics unless absolutely necessary.