Fever
Fever is a warning sign that the body is battling an infection. Fever related to flu is usually higher than 100.4 F (38 C). High-grade fever is a common symptom in the early stages, but not everyone with the flu will experience a fever spike. Sometimes, you can feel chills with or without a fever when the virus is active.
Acetaminophen and ibuprofen are typically both effective fever reducers, although these drugs can not cure the virus.