I've had 2, yes TWO babies that were born lactose intolerant (severely lactase deficient). I still wanted to nurse them though, the only way to do that is to give them a hefty dose of lactase orally right before nursing. The older of those two babies is now almost 3 and has graduated from these drops to strawberry flavored chewable tablets (that I wish they sold).
Obviously, it's literally a life saver that allowed my babies to eat as they should, but I do have complaints.
-It's hard to get the last few drops out of the bottle with the dropper.
-Since they've changed the bottle design the dropper drips when used, which makes a little bit of an oily mess
-Bottle size is so small that we go through it very quickly and it feels so wasteful to throw out all that packaging all the time.