First line of defense would be a change in diet, including increase the amount of fibre as well as fluids (especially water). A gentle laxative such a mineral oil can be used for occasional constipation but not relied upon.
A natural cure for constipation in children is to have them eat prunes or drink some prune juice. There are also medicines on the market for children with constipation.
To cure children's constipation, you first need to look at their diet. More fruits and vegetables will definately help. Get the child to drink more water to keep things going.
The cure would have to be giving them more fiber, stool softeners or changing their diet completely. Also, less milk intake helps with constipation in children. Foods that include fiber (cereal, prunes, apricots, and spinach)
Constipation in children is indicative of a lack of dietary fiber. Fresh fruits and vegetables are the best source, but getting kids to eat them can be a challenge. You can use a fiber supplement, in a chewable table, or something that can be added to juice.