A Q and A on Diarrhea
Diarrhea: straight answers to the questions people actually ask, with the figures behind them.
Passing loose or watery stools more frequently than is normal for you.
Key takeaways
- Common cause: viral gastroenteritis, including norovirus
- Staying home: for 2 days (48 hours) after norovirus symptoms stop
- Most useful single change: Keep fluids up and use an oral rehydration solution if needed.
- Commonest mistake: Antidiarrheal medicines if you have blood in the stool or a fever.
- See a doctor if any of the signs under "When to speak to a doctor" below apply to you.
What is Diarrhea?
Passing loose or watery stools more frequently than is normal for you.
Why does it matter?
Most episodes are short-lived infections, and the main risk in otherwise healthy adults is dehydration rather than the infection itself.
Common cause for Diarrhea?
Viral gastroenteritis, including norovirus.
Staying home for Diarrhea?
For 2 days (48 hours) after norovirus symptoms stop.
Hand hygiene for Diarrhea?
Soap and water; hand sanitizer works poorly against norovirus.
Antidiarrheal medicines for Diarrhea?
Avoid if there is blood in the stool or a fever.
What is the single most useful thing to do?
Keep fluids up and use an oral rehydration solution if needed.
What is the most common mistake?
Antidiarrheal medicines if you have blood in the stool or a fever.
When should I see a doctor?
See your doctor for diarrhea lasting more than 2 days in an adult or more than 24 hours in a child, blood or pus in the stool, black stools, severe abdominal pain, a high fever, or signs of dehydration such as dizziness on standing and passing very little urine. Get advice early for babies, older adults, pregnant women and anyone with a weakened immune system, who dehydrate faster. Call 911 for confusion, fainting or a baby who is very drowsy.
More questions, answered
Should I stop eating if I have diarrhea?
No. Eating when you can helps your body recover and provides the energy and nutrients the bowel lining needs to repair. Start with bland foods and small portions, build up as you feel able, and keep drinking fluids throughout. Small, frequent meals are often easier than large ones.
Do sports drinks work for rehydration?
Sports drinks contain more sugar and fewer salts than oral rehydration solutions. They are fine for mild cases in healthy adults but not ideal for children or significant fluid loss, where extra sugar can worsen diarrhea. Oral rehydration solutions from a pharmacy are a better choice.
How long is norovirus contagious?
Norovirus is most contagious while you have symptoms and for the first few days after they stop. The virus can stay in stool for two weeks or more. Thorough handwashing with soap and water, and cleaning surfaces with a bleach-based product, reduce spread.
Can probiotics prevent diarrhea from antibiotics?
Some probiotic strains may reduce the risk of antibiotic-associated diarrhea in some people. Ask your doctor or pharmacist whether a probiotic is appropriate for you, and check first if you have a weakened immune system, a central line or a serious illness.
What is C. difficile?
C. difficile is a bacterium that can cause severe diarrhea and inflammation of the colon, most often during or after antibiotic use, when normal gut bacteria are disrupted. It needs testing and specific treatment. Tell your doctor if you develop diarrhea during or after antibiotics.
Is chronic diarrhea always serious?
Not always, but it needs investigation. Common causes include IBS, food intolerances and medicines, while celiac disease, inflammatory bowel disease, microscopic colitis and thyroid problems need to be ruled out. Weight loss, bleeding or waking at night to pass stool make prompt assessment more important.
Related topics
- Travelers' Diarrhea: What the Evidence Actually Says (Travel Health)
- What the Guidance Really Says About Norovirus (Infectious Diseases)
- Fluid and Kidney Health: What Published Guidance Supports (Kidney Health)
- The Evidence on Dietary Salt, Without the Hype (Nutrition)
Where to go next
- Diarrhea: Separating Myth From Guidance
- Diarrhea for Beginners: Where to Start
- Diarrhea — the reference entry
- Digestive Health: The Complete Guide
- What the Guidance Really Says About Hemorrhoids
- Food Intolerance: What the Evidence Actually Says
When to speak to a doctor
See your doctor for diarrhea lasting more than 2 days in an adult or more than 24 hours in a child, blood or pus in the stool, black stools, severe abdominal pain, a high fever, or signs of dehydration such as dizziness on standing and passing very little urine. Get advice early for babies, older adults, pregnant women and anyone with a weakened immune system, who dehydrate faster. Call 911 for confusion, fainting or a baby who is very drowsy.
Where this comes from
- National Institute of Diabetes and Digestive and Kidney Diseases — Diarrhea
- CDC — Preventing Norovirus
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.
Spotted something wrong? Report an error on this page. We correct on the page and say what changed.
