My sons dr. (a pediactric gastointerologist) told me that if you give them the whole bottle it would not hurt them, it would just clean them out. Dosing is really a matter of how much they need. My son is 2.5 and been on miralax for almost a year. He gets severly constipated without it. He started off on a full cap. (Up to the white part in the lid) Which is what adults start out on too. But thats what it took to get him going. And he started that dose at just over a year. I just mix it in his milk a dinner everyday. Now he is on about 1/2 a teaspoon. So you should give him a capfull everyday until he goes. Hopefully this is just a one or two time thing for you. I understand completelely, like i said we have been doing this for a year. i am slowly trying to wean him off. so hopefully we are not far. Good luck you you, and hope this helps.