Well, we are born with lactase, and most of us with more than enough.
A baby can get colicky from poor breastfeeding technique resulting in
his getting low fat milk (see Woolridge and Fischer article in Lancet
a few years ago).

We have tried these drops occasionally in the past and surprisingly,
occasionally, underline occasionally (that is occasionally of the
occasional times we have tried them), they work.  But they shouldn't.
The reason is that if you read the instructions, the drops need to sit
in the milk for several hours in order to break down all the lactose.
But maybe we don't have to break it all down, only some.  But lactase
is destroyed in the stomach.  So in theory it should not work and
usually it doesn't.

As a rule, fixing the breastfeeding is the best approach to
breastfeeding problems.

Jack Newman, MD, FRCPC