Experiencing chills without a fever is often an early warning sign of the flu and does not necessarily warrant medical attention, notes Healthline. Chills can be the body's way of preparing for an infection and an increase in core temperature, according to MedlinePlus.
Some causes of chills include colds, pneumonia and strep throat, states MedlinePlus. Meningitis, bacterial or viral gastroenteritis, and infectious mononucleosis may also be to blame. It is advised that an adult see a doctor if chills are accompanied by a fever over 103 degrees Fahrenheit that does not abate after home treatment. Shortness of breath, confusion or stiffness of the neck, frequent urination or a bad cough are also reasons to seek medical attention.