Fever
Your body temperature often spikes when a pathogen like the flu virus triggers your immune system. The immune system is your body’s natural defense against diseases and infections. You may experience a fever while your immune system works to clear out an infection.
Fevers caused by the flu are often higher than 100.4˚F or 38˚C [6]. It is possible to experience chills along with fever or in alternating cycles, although this does not happen to everyone. Some people even have the flu without experiencing any fever at all.
Chills
Chills [7] are another common symptom of the flu. When you have chills, you become more sensitive to cold and feel cold even when you should not. This can be so intense that you begin to physically shiver. This symptom sometimes precedes a fever or co-occurs with one.
It will not magically get rid of the chills, but wrapping yourself in a warm blanket can help reduce the intensity of the chills by raising your body temperature and trapping body heat.