I have to agree with pursuitofpeace, I don't think metamucil has a side effect of hair loss, but I'm just a normal guy so what do I know. Also, I don't believe that taking a multivitamin will make your IBS symptoms worse unless they are derived from dairy or gluten or something like that. But like I mentioned before, I'm not a genius on this topic. Maybe the hair loss is a sign that your are deficient in something like zinc, vitamin b, or vitamin a. Who knows?