This is for Rainbow3,
I am not sure how old your daughter is now.
Yes You can give to teenage, please just give one drop a day. It may take little longer to cure but better to be safe.
As I grew up In punjab, India as farming family.
We had Neem tree on our land. As teen agers we used to eat few ripe Neem fruit everyday without knowing all the benefits. We did not get sick from eating it. We used to boil green Neem tree leafs to treat skin infections etc;
Now I am 60+ and my Dr say's take Neem orally to cure yeast. I am about to start doing this tomorrow.