You can give any iron drops which are easily available at your place...

Was your son premature or low birth weight ? If yes you need to start iron drops which can be calculated according to his weight & presence of elemental iron in preparation.but if your child had been of normal birth weight no need of iron supplement. But supplement feeding weaning must be started at right age when he will be six months

U can use ferronia-xt 3drops once daily

What is the gestation at which your child was born,  if term then not required.

Iron is recommended in preterm child after 21 days of age. In full term child no need to give unless it is required ( low hemoglobin or low iron)