It's best to consult with the child's pediatrician or get the child evaluated by an urgent care or emergency room physician if the nausea is severe enough to cause uncontrollable vomiting or is hindering the child from oral intake. If the nausea is mild, it is likely medication is not
needed.

Treatment of nausea and vomiting depends on the underlying etiology and involves targeted treatment for certain disorders, supportive care, and, occasionally for mild episodic cases, you can use antiemetics, OTC antihistamines I hope that helps