Hi, If I were your treating Doctor for this case of throwing up. I would ask you to give as much water as possible in small sips. Clinical assessment of dehydration can be difficult, especially in young infants, and rarely predicts the exact degree of dehydration accurately. The most useful individual signs for predicting 5% dehydration in children are an abnormal capillary refill time, abnormal skin turgor and abnormal respiratory pattern. Combinations of examination signs provide a much better method than any individual signs in assessing the degree of dehydration. If he refuse to drink water he could get intravenous fluids depending on his skin turgor (pinch test). Mild-Moderate dehydration kids have : Restlessness or irritability, Sunken eyes, Thirsty and drinks eagerly. Clinical features of mild-to-moderate dehydration; 2 or more of: Restlessness or irritability, Sunken eyes (also ask the parent), Thirsty and drinks eagerly. These kids may take pediolyte/ rice water/ coconut water/ORS- oral rehydration therapy which will replenish electrolytes Clinical features of severe dehydration; 2 or more of: Abnormally sleepy or lethargic. Sunken eyes. Drinking poorly or not at all. Pinch test (skin turgor): the sign is unreliable in obese or severely malnourished children. These kids have to receive intravenous fluids to recover the body fluid levels. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Wishing your kid good health.