<<Disclaimer: Verify this information before applying it to your situation.>> The daily kind contains lactose. It is a lactose base. I don't know about the once a week kind. Best to check on the ingredients. If you are lactose intolerant, please keep this in mind. Didronel or Etidronate has no lactose, but I haven't checked on the GF status yet. It doesn't work quite as well. Vicki