my 21month old baby is sucking thumb how to break this habit please help..we have tried a thumb sucking solution but it has not worked.

A. Neem oil you can add into some transparent nail paint okay and when your child goes to sleep applied on the entire fingers and including the nails I think that is going to be something which is very good because whenever the child is going to take it into the mouth the child will eventually give up over the period so use it on all the finger and thumb of the child