What are the symptoms of stomach flu?
Stomach flu typically causes watery diarrhea, nausea, vomiting, abdominal cramps, a low-grade fever, and body aches, usually starting one to two days after exposure and lasting one to three days. The main danger sign is dehydration from fluid loss.
The Typical Symptom Picture
Stomach flu (viral gastroenteritis) usually announces itself one to two days after you are exposed to a virus like norovirus or rotavirus. The core symptoms are:
- Watery diarrhea — frequent loose or liquid stools, usually without blood, that drain fluids and electrolytes quickly.
- Nausea and vomiting — repeated vomiting that makes it hard to keep food or liquids down.
- Abdominal cramps — intermittent belly pain from irritation of the stomach and intestines.
- Low-grade fever and chills — a mild fever as your body fights the infection.
- Muscle aches, headache, and fatigue — the general run-down feeling of a viral gut infection.
- Loss of appetite — reduced desire to eat or drink, which can worsen fluid loss if it lasts.
Most people have some, not all, of these. Symptoms generally peak and then ease within one to three days.
What Your Symptoms Are Telling You
The symptoms themselves are the body clearing a virus, and on their own they are rarely harmful. What matters is the fluid you are losing through vomiting and diarrhea. That is why hydration, not stopping every symptom, is the goal while you recover. Watch your urine: pale and regular means you are keeping up; dark, scant, or absent urine means fluids are falling behind.
Symptoms That Are Not Just Stomach Flu
Some symptoms point away from a simple virus and deserve attention:
- Blood in vomit or stool, or black, tarry stools — suggests bleeding, not routine gastroenteritis.
- Pain that localizes to the lower right belly — can indicate appendicitis rather than diffuse cramping.
- Fever above 103°F, or a stiff neck with severe headache — signals a more serious infection.
- Signs of dehydration — dizziness, confusion, racing heartbeat, sunken eyes, or no urination for 8+ hours.
Stomach Flu vs. Influenza
Despite the name, stomach flu is not related to influenza. The flu is a respiratory virus causing cough, fever, and body aches, and the flu vaccine does not protect against gastroenteritis.
For a complete guide, see our stomach flu page. If your symptoms include any of the danger signs above, walk in to Bellaire ER at 5302 Bellaire Blvd., open 24/7, or call (713) 660-0001.