I'm not sure that you can acutally overdose. I think your body is going to expel what you can't use. I was just reading a study yesterday on probiotics that talked about doctors giving their patients high dose probiotics during intestinal illnesses. The results were incredibly good. Not sure if I would 100 billion. I think my mega dose probiotics are about 5 billion? What if you started out at 50 billion taking them throughout the day? I just think that if you take too much the extra dosage might just end up getting expelled and not used.