Infantile hemangiomas are prevalent in the first few months of life and can be associated with risks of scarring, blindness, ulcerations, and airway obstruction depending on the location of lesions. Options for therapy include surgery, laser therapy, or medications. Propranolol is the only US Food and Drug Administration-approved medication option. Propranolol is a nonselective beta-blocker that crosses the blood-brain barrier because of its high lipophilicity, which increases the likelihood of central nervous system effects. In this case, a preterm infant developed infantile hemangiomas on the left forearm, left trunk, left buttock, and nasal tip. The patient was treated with propranolol and concurrently required placement into a heated incubator and was subsequently unable to wean from the incubator. Upon discontinuation of propranolol, temperature instability resolved. Atenolol, a cardioselective beta-blocker that does not cross the blood-brain barrier, was then initiated for the infantile hemangiomas and displayed no adverse effect on the thermoregulation of the infant.