I did a quick search and it appears there are prescription probiotics so it would be worth asking your doctor. I buy the Lactobif 30 from iHerb and pay $22 for 60. I take just one a day so that's just a little over $10/month. It has 8 different strains and so far I've had no diarrhea and nausea went away after a few weeks so I am comfortable sticking with the product.