Acute Diarrhea

  • 80% of acute Diarrhea is caused by infections (viruses, Bacteria and parasites) in addition to food poisoning
  • About 20% is caused by drugs side effects
  • Rarely diarrhea is caused by fecal impaction, kidney & pelvic infections and intestinal ischemia

Causes of Acute Diarrhea

Food and Water borne Infectious Diarrhea

  • Most infectious diarrhea are acquired by the fecal oral route from contaminated water, food or person to person
  • Symptoms may include nausea, vomiting and abdominal cramping and occasionally fever and blood in stools
  • Viral Causes include Norovirus (most common cause) in adults and Rotavirus in children
  • Ebola virus can cause massive watery diarrhea
  • Bacterial common causes include Salmonella, Campylobacter and E.Coli. Less common causes include Shigella
  • Outbreaks can happen in petting zoos or from ingestion of raw ground beef or green leafy vegetables
  • Outbreaks of Cryptosporidium has been reported in water parks
  • Occasionally the bacteria can release a toxin (like Shigella) that can cause diarrhea with blood
  • Ingesting seafood contaminated with Vibrio can cause diarrhea

Food and Environmental Poisoning

  •  Food poisoning is caused by a bad chemical (toxin) produced by bacteria
  • The diarrhea resolves quickly after flushing the bad chemical (24 to 48 hours)
  • Most common causes are Staph Aureus and Bacillus Cereus in addition to Clostridium
  • Some mushrooms (Amanita) can cause food poisoning
  • Ingestion of heavy metals like Arsenic (rat poisoning) ,Gold, Lead and Mercury
  • Insecticides poisoning can cause acute illness with diarrhea
  • Seafood can cause many types of food poisoning syndromes

Traveler’s Diarrhea

  •  North American traveling to developing countries are at risk for diarrhea
  • Traveling on planes and cruise ships are risk factors
  • Common causes are E.Coli, Shigella, Giardiasis and Norovirus
  • Most are easily treated and self limited

Antibiotics Associated Diarrhea

  • Antibiotics are a common cause of diarrhea (20% of inpatients on antibiotics experience diarrhea)
  • Most diarrhea cease after stopping the antibiotics
  • 30% of the antibiotics related hospital diarrhea is caused by Clostridium Difficile ( this bacteria takes over the lining of the Colon normal bacteria weakened by the antibiotic)
  • C.Diff. colitis can cause severe  Diarrhea, Colitis or Toxic Megacolon and can be quite serious

Other Causes of Diarrhea

  •  Chemotherapy and radiation therapy
  • Day Care Diarrhea: most commonly caused by Rotavirus and Norovirus, but it may be caused by Shigella,
    Cryptosporidium and Giardiasis
  • Runner’s Diarrhea: it occurs in 10 to 25% of vigorous runner

Red Flags in Diarrhea

Most acute diarrhea are mild and self limited and do not justify the cost or the morbidity associated with pharmacologic or diagnostic testing Indications for Evaluation in urgent care or ER are:
  • Severe diarrhea causing dehydration
  • Blood in stool
  • Fever >101 F
  • Duration over 48 hours without improvement
  •  Recent antibiotics use
  •  New community outbreak
  •  Severe abdominal pain
  •  Elderly patient or very young (infant)
  •  Immune compromised patient

Simplified Overview of Acute Diarrhea Management

Patients with mild acute diarrhea without red flags should be able to manage their diarrhea with oral hydration and antidiarrheal medications

***If patient has any of the above red flag signs —> he should be evaluated in ER or UC

***If patient has severe pain, dehydrated, passing blood in stool or has unstable vitals —> he should be evaluated in ER

After the hydration and stabilization is achieved the work up for a cause can be startedP


  Severe Illness / Sicker Patients 

 Mild Illness and stable patient without red flags

ER Evaluation and stabilization.

Observation at home or quick UC evaluation

Stool Culture.

  Trial of oral antibiotics (5 days) before testing 



Stool culture if no improvement or resolution



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