Fatigue
Fatigue is a feeling of intense tiredness. Unlike regular tiredness, it is more persistent and does not disappear with rest. Physical activity is not the cause of excessive fatigue. It usually is a sign that there is something amiss in your normal system functioning.
Many people with the flu report experiencing sudden and severe [2] fatigue as one of their first symptoms. It typically precedes other flu symptoms and can interfere with your ability to perform daily tasks. This is one of the reasons a lot of people call in sick when they have the flu.
When dealing with flu-induced fatigue, it is important to stay well-rested. Avoid physical activities that can wear you out. This way you avoid worsening your fatigue and give your immune system the boost it needs to combat the virus.