Diarrhea: When to Worry, and Where to Go

The red flags that mean call 911, when the ER, urgent care, or your doctor is the right choice, likely causes, and what it costs. Or answer a few questions for a recommendation tailored to you.

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Educational guidance, not a diagnosis. Medically reviewed by Dr. Prathima Madda, MBBS. Updated July 15, 2026.

Call 911 now if you have:

Confusion, fainting, or unable to stay awake along with diarrhea (signs of severe dehydration or shock)
Vomiting or passing large amounts of blood, or many stools that look like black tar (possible major GI bleeding)
Severe, constant abdominal pain with a hard, rigid, or board-like belly (possible perforation or obstruction)
Rapid or pounding heartbeat, cold clammy skin, and lightheadedness with almost no urine (circulatory collapse from fluid loss)
Diarrhea plus stiff neck, worst-ever headache, trouble breathing, or chest pain
Signs of a severe allergic reaction (facial/throat swelling, wheezing, hives) after a food or medication

When in doubt about a possible emergency, call 911. Do not drive yourself.

Most sudden diarrhea in healthy adults is viral and resolves in 1-2 days; the main job at home is staying hydrated with fluids and oral rehydration solutions.
Red flags that mean urgent or emergency care: blood or black tarry stools, high fever, severe belly pain, or signs of dehydration (little urine, dizziness, confusion).
Infants, older adults, pregnant people, and those who are immunocompromised or have chronic illness should seek care earlier, because they dehydrate and worsen faster.

ER, Urgent Care, Doctor, or Home?

Go to the ER

Go to the ER when diarrhea is combined with significant bleeding, high fever, severe abdominal pain, or dehydration that home fluids cannot keep up with, because these can point to serious infection, GI bleeding, or dangerous fluid and electrolyte loss that may need IV fluids and urgent testing. Choose the ER over urgent care when you feel very sick, are fainting, or fall into a high-risk group.

Blood in the stool that is more than a streak, maroon-colored stool, or repeated black tarry stools
Fever of 102°F (39°C) or higher, especially with shaking chills
Signs of significant dehydration you cannot fix at home: very little or no urine for 8+ hours, extreme weakness, dizziness on standing, dry mouth, sunken eyes
Severe or worsening abdominal or rectal pain, or pain concentrated in the lower right belly
Persistent vomiting so you cannot keep any fluids down
Diarrhea in someone who is pregnant, very frail, immunocompromised, or has serious heart, kidney, or liver disease and appears to be getting worse
In an infant or young child: no wet diaper for 6 to 8 hours, no tears when crying, a sunken soft spot (fontanelle) or sunken eyes, or unusual sleepiness or floppiness (children dehydrate quickly)
You have diabetes on insulin and cannot keep fluids or food down (risk of dangerously high blood sugar and diabetic ketoacidosis)

Urgent care

Diarrhea lasting more than 2 days (more than 24 hours in a child) with no improvement
Six or more loose stools in a day, or diarrhea that keeps waking you at night
Moderate dehydration (thirst, dark urine, dizziness) that you cannot get ahead of with oral fluids but you are still alert and able to drink
Fever up to about 101-102°F with diarrhea but no other red flags
Recent travel abroad, recent antibiotics, or a known sick contact, with symptoms that are lingering but stable
Watery diarrhea that started during or after recent antibiotics or a hospital stay (possible C. difficile infection that needs specific testing and treatment)

See your doctor / telehealth

Diarrhea that lasts more than a couple of days, keeps coming back, or has gone on for weeks (chronic diarrhea)
Diarrhea after starting a new medication or antibiotic (do not stop a prescribed drug without asking first)
A pattern of loose stools with cramping, mucus, unexplained weight loss, or waking at night to have a bowel movement
You are over 65, pregnant, or have a chronic condition and have mild but persistent symptoms
You want testing for parasites, a stool culture, or evaluation of ongoing digestive symptoms

Safe to manage at home

Most short-term (acute) diarrhea in an otherwise healthy adult is viral and clears on its own within a day or two; focus on staying hydrated
Drink plenty of fluids: water, broth, and oral rehydration solutions; for adults, diluted sports drinks can help replace salts (avoid heavy sugar and alcohol)
Eat when you can tolerate it; bland, easy foods (bananas, rice, toast, applesauce, crackers) are gentle, and you do not need to fast
Over-the-counter loperamide (Imodium) can ease symptoms in adults, but avoid it if you have bloody stools or high fever, and do not use it in young children without a doctor's advice
Wash hands well and watch for warning signs; if symptoms last beyond 2 days or dehydration sets in, move up the ladder to a clinician

Not sure which fits your situation? Answer a few questions for a recommendation, or see the full ER vs. urgent care guide.

Common Causes

These are possibilities to discuss with a clinician, not a diagnosis. Only an exam and sometimes tests can tell which applies to you.

Viral gastroenteritis ("stomach flu"), such as norovirus or rotavirus - the most common cause of sudden diarrhea
Bacterial or parasitic infection from contaminated food or water, including traveler's diarrhea
Antibiotic-associated diarrhea, including C. difficile after recent antibiotic use
Food intolerance or sensitivity (for example lactose), or a reaction to a medication such as magnesium or metformin
Chronic conditions like irritable bowel syndrome, inflammatory bowel disease (Crohn's or ulcerative colitis), or celiac disease
Anxiety/stress or, rarely, thyroid problems and other digestive disorders (this list is general education, not a diagnosis)

What to Expect if You Are Seen

A clinician will ask about duration, stool frequency and appearance (blood, black, mucus), fever, travel, food, medications, and sick contacts, and check you for dehydration
They may check vital signs and orthostatic blood pressure and, if needed, order blood tests for electrolytes and kidney function
A stool sample may be tested for bacteria, C. difficile toxin, parasites, or blood if symptoms are severe, bloody, or prolonged
If you are dehydrated, you may receive oral rehydration or IV fluids; antibiotics are used only for specific infections, not routine diarrhea
For chronic or bloody diarrhea, you may be referred for further workup such as a colonoscopy or specialist evaluation

Worried about the cost?

See typical pricing in our doctor visit cost guide and ER visit cost guide, or estimate your exact cost. Uninsured? Check hospital charity care. Already have a bill? Bill Defense can negotiate it down.

Before You Go, Have This Ready

A rough log: when it started, how many stools per day, and whether there is blood, black color, or mucus
Your temperature readings and any other symptoms (vomiting, pain, dizziness, urine output)
A list of medications, supplements, and recent antibiotics, plus any recent travel or suspect foods
Your medical history and, if possible, a photo of any concerning stool to show the clinician

Still not sure? Let the free checker decide

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Frequently Asked Questions

How long is it normal to have diarrhea before I worry?

In a healthy adult, most diarrhea improves within 1-2 days. Contact a doctor if it lasts more than 2 days without improving (more than 24 hours in a child), or sooner if you have blood in the stool, high fever, severe pain, or signs of dehydration.

When does diarrhea count as an emergency?

Call 911 or go to the ER for confusion, fainting, a rigid painful belly, large amounts of blood or repeated black tarry stools, or dehydration so severe you cannot keep fluids down and are barely urinating. These can signal serious bleeding, infection, or dangerous fluid loss.

What are the signs of dehydration I should watch for?

In adults: extreme thirst, dark urine or very little urine, dry mouth, fatigue, dizziness, and lightheadedness on standing. In infants and young children: no wet diaper for 3 or more hours, no tears when crying, a sunken soft spot, sunken eyes, and unusual drowsiness. Children can dehydrate quickly, so seek care early.

Is it safe to take Imodium (loperamide) for diarrhea?

For simple watery diarrhea in adults, loperamide can reduce symptoms and is generally fine short term. Avoid it if you have bloody stools or a high fever, because slowing the gut can worsen certain infections. Do not give it to young children without a doctor's guidance, and follow package dosing.

When is diarrhea a sign of something serious like C. diff or IBD?

Diarrhea after recent antibiotics, especially with fever and cramping, can be C. difficile and needs testing. Diarrhea that is chronic, bloody, wakes you at night, or comes with unexplained weight loss can point to inflammatory bowel disease or other conditions and should be evaluated by a doctor.

More symptom guides

All symptom guides Free symptom checker ER vs. urgent care

Sources

MedlinePlus (NIH/National Library of Medicine) - Diarrhea
NIDDK/NIH - Symptoms and Causes of Diarrhea
Mayo Clinic - Diarrhea: When to see a doctor
CDC - Food safety and diarrheal illness / dehydration guidance
Merck Manual Consumer Version - Diarrhea in Adults

This guide is educational and not a substitute for professional medical advice. For an emergency, call 911. Medically reviewed by Dr. Prathima Madda, MBBS. Last updated July 15, 2026.