What are the main signs and symptoms of gastroenteritis in teens and adults?

Nausea, vomiting. Diarrhea, possibly fever and chills, dehydration, body aches, headache.
Sx's. Gastroenteritis symptoms may include: diarrhea, nausea, vomiting, abdominal cramps/pain, headaches, muscular aches & pains as well as fever (low grade). Bloody stools are not usually associated with gastroenteritis. According to the CDC, viral gastroenteritis usually has a duration of 1 to 10 days (depending on the specific virus). The average is 1 to 3 days.