Stomach Flu: Nausea, Vomiting, Diarrhea and Dehydration

What it involves

NIDDK describes viral gastroenteritis as an infection of your intestines that typically causes watery diarrhea, abdominal pain or cramping, nausea or vomiting, and sometimes fever. People often call it the stomach flu, but NIDDK says that term is not medically correct, because flu viruses do not cause it. Many different viruses can, and it spreads through contact with particles of an infected person's stool or vomit.

Who this is for

• Adults with vomiting or diarrhea who are not sure whether they can ride it out at home
• Older adults and patients with diabetes or kidney disease who dehydrate more easily
• Patients who cannot keep liquids down or are urinating much less than usual
• Patients caring for a household with several sick members who want a plan to limit spread

What to expect

• Questions about how many days you have been sick, how often you vomit, and what you can drink
• A check of your vital signs and signs of dehydration, plus a belly exam
• A review of your regular medicines, so your provider can tell you what to do about them during the illness
• A plan for fluids, diet, medicines to avoid, and what would mean coming back or going to the ER

Which viruses cause it and how long they last

NIDDK names norovirus as the most common cause, with symptoms usually starting 12 to 48 hours after contact and lasting 1 to 3 days. Rotavirus symptoms start about two days after contact and last 3 to 8 days, adenovirus symptoms last 1 to 2 weeks, and astrovirus symptoms 1 to 4 days. Rotavirus, adenovirus, and astrovirus most often infect infants and young children but can infect adults. In the United States, norovirus, rotavirus, and astrovirus are more likely to cause infections in winter.

Dehydration is the complication that matters

NIDDK calls dehydration the most common complication of viral gastroenteritis. MedlinePlus says it happens when you lose more fluid than you take in, and lists vomiting, diarrhea, fever, and sweating among the causes. In adults, the signs include: Fluid loss can also trigger muscle cramps, and the muscle cramps guide explains how low fluid and mineral levels make them more likely.

• Extreme thirst and a dry mouth
• Urinating less than usual, with dark-colored urine
• Feeling tired, dizzy, or lightheaded
• Sunken eyes or cheeks, or skin that does not flatten right away when pinched

What to drink and when you can eat

NIDDK says treatment is to replace lost fluids and electrolytes. If vomiting is a problem, sip small amounts of clear liquids. Most adults can use water, fruit juices, sports drinks, or broths, and saltine crackers can help replace electrolytes. Older adults, adults with a weakened immune system, and anyone with severe diarrhea or dehydration should use an oral rehydration solution. NIDDK says that when appetite returns you can usually go back to your normal diet, and that restricted diets do not help treat the illness.

Medicines: what helps and what does not

NIDDK says antibiotics do not work on viral infections and are not prescribed for viral gastroenteritis, though a provider may prescribe medicine to control severe vomiting. Adults can sometimes use over-the-counter loperamide or bismuth subsalicylate, but NIDDK says not to use them if you have bloody diarrhea or fever, which can signal an infection with bacteria or parasites. Check with your provider first if you take other regular medicines, and do not stop or change any of them on your own.

Signs that mean being seen the same day

NIDDK says adults should see a doctor right away for a change in mental state, diarrhea lasting more than two days, a high fever, frequent vomiting, six or more loose stools in a day, severe abdominal or rectal pain, black or bloody stools, or signs of dehydration. Older adults, pregnant women, and people with weakened immune systems should call at any sign. The sick visit versus urgent care versus ER guide sorts which setting fits, and dizziness on standing is covered in the dizziness evaluation. Dehydration from heat and sun exposure follows a different path from stomach illness, and the heat exhaustion and heat stroke guide explains the warning signs and first aid.

Stopping it from spreading at home

NIDDK advises washing hands with soap and water after using the bathroom and before handling or eating food, cleaning contaminated surfaces with a diluted bleach mixture, and washing soiled laundry in detergent on the longest cycle. Anyone who is sick should avoid preparing food for others until two days after symptoms stop. The flu vaccine does not protect against viral gastroenteritis. When diarrhea lingers past the acute illness, the persistent diarrhea evaluation covers what else a provider considers.

Sources

• NIDDK — Viral Gastroenteritis (Stomach Flu): Symptoms & Causes
• NIDDK — Viral Gastroenteritis (Stomach Flu): Treatment
• MedlinePlus — Dehydration