A doctor would consider hospital admission for scarlet fever if the patient shows signs of severe illness or complications. This can include inability to drink or eat leading to dehydration, a high fever that doesn’t respond to medications, or evidence of serious complications like peritonsillar abscess, difficulty breathing, or signs of rheumatic fever or kidney involvement. Admission may also be necessary for very young children, those with weakened immune systems, or anyone who cannot be safely managed at home. The hospital allows for close monitoring, IV fluids, and rapid treatment if complications arise.