depends on if he ate something before or if he is allergic to a material in the medicine or he could have a bacteria that rejects the drugs it depends on the circumstances but what i would do if they did eat something dont have them eat atleast 4 hours before so you can clear their system and then give them the medicine and if he vomits again take him to the doctor or if he has some unusual reaction god bless him😁❤️

Resist the urge to give another dose to your child after they vomit. it may lead to overdose.