Fevers are helpful because they increase the body's temperature to a point where bacteria and viruses do not thrive, according to MedlinePlus. Most bacteria and viruses thrive best at the body's normal temperature of 98.6 degrees Fahrenheit. Defense mechanisms in the body work better at higher temperatures, states MedicineNet.
Higher fevers of 104 degrees Fahrenheit and up demand immediate medical attention, as reported by MedicineNet. These high temperatures can cause delirium and convulsions. Fevers above 107.6 degrees Fahrenheit can result in brain damage, according to MedlinePlus. Infants and toddlers require medical attention with even low-grade fevers, as reported by Mayo Clinic.
Fevers can result in response to almost any infection, states MedlinePlus. Skin infections, urinary tract infections, ear infections and bone infections can cause fever just as a cold or flu can. Children sometimes get a low-grade fever after immunizations, and teething babies sometimes develop fevers. Autoimmune and inflammatory disorders also cause fever. The first symptom of cancer may manifest as a fever.
Symptoms such as sweating, shivering, muscle aches, headache, loss of appetite, weakness and dehydration indicate a fever, according to Mayo Clinic. A rapid heart rate, skin flushing and feelings of dizziness, faintness or lightheadedness are also symptoms of fever, states MedicineNet.