Sudden, excessive fatigue is one of the very first signs of the flu, according to Healthline. Extreme weakness is another sign of the body preparing to combat the flu rather than a cold. More » Health Pain & Symptoms

Some of the earliest signs of the flu include the sudden onset of excessive fatigue, aches and chills, coughing and chest tightness, soreness in the throat, fever and gastrointestinal problems, such as nausea, stomach pa... More » Health Conditions & Diseases Cold & Flu

The first physical signs of HIV are very similar to those of the flu, according to the Mayo Clinic. Symptoms may include fever, headache, fatigue and joint pain, along with diarrhea and a red, nonitchy rash. More » Health Conditions & Diseases

Common symptoms of the flu include a cough, sore throat, fever of 100 degrees or higher, chills, fatigue and headache, according to Some people also have nausea, vomiting or diarrhea, although these symptoms are... More » Health Pain & Symptoms

Chills and headache can be a sign of a flu virus, even if a person doesn't have a fever, according to Healthline. Chills and body aches are often precursors to a fever when flu is the underlying cause. Other symptoms of ... More »

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 increa... More » Health Pain & Symptoms

Some of the most obvious signs of dehydration include thirst, dark-colored urine, fatigue and irritability. According to the Lake Erie College of Medicine, dehydration can easily occur during hot and humid periods becaus... More » Health Pain & Symptoms