It can occur even without disease, as there are a lot of medications that can cause nausea and vomiting. Nausea in gastroenteritis may be due to the release of toxins from the bacteria or a delay in stomach emptying after meals (gastroparesis).
Damaged cells and immune cells release chemicals which trigger a response in the brain. The amount of chemical signals that reach the brain determines the severity of nausea and vomiting.
Fever is another common symptom of many illnesses. The presence of a fever almost always indicates there is an infection. While a fever may not always be present with acute gastroenteritis, it can be an indicator for a more serious infection.
Fevers occur as a natural defense mechanism against bacteria and viruses. The body heats itself up in an attempt to kill the pathogens. Low-grade fevers are above 38°C, while high-grade fevers are 39.4°C or higher. Prolonged high-grade fevers can cause more harm than good. High-grade fevers above 40°C for several hours to days can even cause permanent brain and nerve damage.
Dehydration is a concern whenever there is fluid leaving the body, especially with diarrhea and vomiting. Frequent, watery stools can cause the loss of not only water but also essential nutrients, vitamins, and electrolytes.
Dehydration itself is not a symptom, but rather its own condition. Because people lose more than just water during episodes of diarrhea, it is important to rehydrate with both water and electrolytes.
Mild signs of dehydration include dry or chapped lips and feelings of extreme thirst. Severe signs and symptoms of dehydration include muscle weakness and loss of consciousness. Mild dehydration can be treated at home while more severe dehydration is a medical emergency.