Purpose: We report two cases of sudden intraocular pressure (IOP) elevation in children after steroid treatment. Case summary: (Case 1) An 8-year-old boy visited the hospital with vomiting and headache that had begun 3 days after application of dexamethasone eyedrops. IOPs were 55 and 62 mmHg in the right and left eyes, respectively; both anterior chambers were normal. The eyedrops were stopped and timolol/dorzolamide was applied twice daily. After intravenous mannitol injection, the IOPs of both eyes decreased to 18 mmHg within 24 hours. (Case 2) A 10-year-old boy diagnosed with coronavirus disease 2019 three days prior had been prescribed methylprednisolone 4 mg twice daily; he visited the hospital with headache, eye pain, and decreased vision that began 1 day after medication. IOPs were 41 and 54 mmHg in the right and left eyes, respectively; both anterior chambers were normal. After drug discontinuation, timolol/dorzolamide, brimonidine, and latanoprost eyedrops were applied. Subsequently, after intravenous mannitol injection, the IOPs decreased within 24 hours to 7 and 16 mmHg in the right and left eyes, respectively; they remained stable. However, thinning was observed in the retinal nerve fiber and ganglion cell-inner plexiform layer. Conclusions: Children can develop rapid IOP elevation after even 1 day of steroid use; residual structural damage may be present, despite prompt treatment. Clinicians must closely monitor such patients for atypical IOP elevation.