In an adult, any temperature over 103 degrees Fahrenheit is considered dangerous, according to the Mayo Clinic. For babies under three months, a temperature over 100.4 degrees Fahrenheit requires a call to a doctor, while for older children and infants, any fever over 102 degrees Fahrenheit or one that lasts longer than one day necessitates an examination by a doctor.
According to the Mayo Clinic, fever is a sign of various medical conditions, including infection. While most fevers are not dangerous and work as the body's way of healing itself, any fever in an adult that lasts longer than three days warrants a call to the doctor, as it can signify a more significant problem that needs medical treatment.
To keep a fever down and increase the comfort level of the patient, WebMD recommends taking fever-reducing medication for any fever over 102 degrees Fahrenheit. Acetaminophen and ibuprofen both offer relief to aching muscles, bring down high temperatures and alleviate other symptoms that accompany fever. Children under 19 should not be given aspirin, as it is linked to the rare but sometimes fatal disorder Reye's syndrome. Speak to a doctor before giving a baby under three months of age fever medicine to rule out any other serious illness.