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Diarrhea types, causes and treatment

Diarrhea types, causes and treatment

Diarrhea is the reversal of the normal net absorptive status of water and electrolyte absorption to secretion. The augmented water content in the stools (above the normal value of approximately 10 mL/kg/d in the infant and young child, or 200 g/d in the teenager and adult) is due to an imbalance in the physiology of the small and large intestinal processes involved in the absorption of ions, organic substrates, and thus water.

What are the symptoms of diarrhea?

The symptoms you can experience when you have diarrhea can vary depending on if it’s mild or severe and what the cause of the diarrhea happens to be. There’s a link between severe cases of diarrhea and a medical condition that needs to be treated.

When you have diarrhea, you may experience all of these symptoms or only a few. The main symptom of diarrhea is loose or watery stool.

Other symptoms of mild diarrhea can include:

  • Bloating or cramps in the abdomen.
  • A strong and urgent need to have a bowel movement.
  • Nausea (upset stomach).

If you have severe diarrhea, you may experience symptoms like:

  • Fever.
  • Weight loss.
  • Dehydration.
  • Severe pain.
  • Vomiting.
  • Blood.

Severe diarrhea can lead to significant complications. If you have these symptoms, call your healthcare provider and seek medical attention.

Different types of Diarrheas

Acute Diarrhea

Diarrhea acute in onset and persisting for less than 2 weeks is most commonly caused by infectious agents, bacterial toxins (either preformed or produced in the gut), or medi­cations. Community outbreaks (including nursing homes, schools, cruise ships) suggest a viral etiology or a common food source. Similar recent illnesses in family members suggest an infectious origin. Ingestion of improperly stored or prepared food implicates food poisoning. Pregnant women have an increased risk of developing listeriosis. Day care attendance or exposure to unpurified water (camping, swimming) may result in infection with Giardia

or Crypto­sporidium. Large Cyclospora outbreaks

Antibiotic adminis­tration within the preceding several weeks increases the likelihood of C difficile colitis. Finally, risk factors for HIV infection or sexually transmitted diseases should be determined. Persons engaging in anal intercourse or oral-anal sexual activities are at risk for a variety of infections that cause proctitis, including gonorrhea, syphi­lis, lymphogranuloma venereum, and herpes simplex. have been traced to contaminated produce. Recent travel abroad suggests “traveler’s diarrhea”.

Noninflammatory Diarrhea

Watery, nonbloody diarrhea associated with periumbilical cramps, bloating, nausea, or vomiting suggests a small bowel source caused by either a toxin-producing bacterium (enterotoxigenic E coli [ETEC], Staphylococcus aureus, Bacillus cereus, Clostridium perfringens) or other agents (viruses, Giardia) that disrupt normal absorption and secretory process in the small intestine. Prominent vomit­ing suggests viral enteritis or S aureus food poisoning. Although typically mild, the diarrhea (which originates in the small intestine) can be voluminous and result in dehy­dration with hypokalemia and metabolic acidosis (eg, cholera). Because tissue invasion does not occur, fecal leu­kocytes are not present.

Inflammatory Diarrhea

The presence of fever and bloody diarrhea (dysentery) indicates colonic tissue damage caused by invasion (shigel­losis, salmonellosis, Campylobacter or Yersinia infection, amebiasis) or a toxin (C difficile, Shiga-toxin–producing E coli [STEC; also known as enterohemorrhagic E coli]). Because these organisms predominantly involve the colon, the diarrhea is small in volume (less than 1 L/day) and associated with left lower quadrant cramps, urgency, and tenesmus. Fecal leukocytes or lactoferrin usually are pres­ent in infections with invasive organisms. E coli O157:H7 is a Shiga-toxin–producing noninvasive organism most com­monly acquired from contaminated meat that has resulted in several outbreaks of an acute, often severe hemorrhagic colitis.

Infectious dysentery must be distinguished from acute ulcerative colitis, which may also present acutely with fever, abdominal pain, and bloody diarrhea. Diarrhea that per­sists for more than 14 days is not attributable to bacterial pathogens (except for C difficile) and should be evaluated as chronic diarrhea.



Most mild diarrhea will not lead to dehydration provided the patient takes adequate oral fluids containing carbohydrates and electrolytes. Patients find it more comfortable to rest the bowel by avoiding high-fiber foods, fats, milk products, caf­feine, and alcohol. Frequent feedings of tea, “flat” carbonated beverages, and soft, easily digested foods (eg, soups, crackers, bananas, applesauce, rice, toast) are encouraged.


In more severe diarrhea, dehydration can occur quickly, especially in children and frail older adults. Oral rehydra­tion with fluids containing glucose, Na+, K+, Cl–, and bicar­bonate or citrate is preferred when feasible. A convenient mixture is ½ tsp salt (3.5 g), 1 tsp baking soda (2.5 g NaHCO3), 8 tsp sugar (40 g), and 8 oz orange juice (1.5 g KCl), diluted to 1 L with water. Alternatively, oral electro­lyte solutions (eg, Pedialyte, Gatorade) are readily available. Fluids should be given at rates of 50–200 mL/kg/24 h depending on the hydration status. Intravenous fluids (lac­tated Ringer injection) are preferred in patients with severe dehydration.

Antidiarrheal Agents

Antidiarrheal agents may be used safely in patients with mild to moderate diarrheal illnesses to improve patient comfort. Opioid agents help decrease the stool number and liquidity and control fecal urgency. However, they should not be used in patients with bloody diarrhea, high fever, or systemic toxicity and should be discontinued in patients whose diarrhea is worsening despite therapy. With these provisos, such drugs provide excellent symptomatic relief. Loperamide is preferred, in a dosage of 4 mg orally initially, followed by 2 mg after each loose stool (maximum: 8 mg/24 h).

Bismuth subsalicylate (Pepto-Bismol), two tablets or 30 mL orally four times daily, reduces symptoms in patients with traveler’s diarrhea by virtue of its anti-inflammatory and antibacterial properties. It also reduces vomiting associated with viral enteritis. Anticholinergic agents (eg, diphenoxylate with atropine) are contraindicated in acute diarrhea because of the rare precipitation of toxic megacolon.

Antibiotic Therapy

Empiric treatment: Empiric antibiotic treatment of patients with acute, community-acquired diarrhea generally is not indicated. Even patients with inflammatory diarrhea caused by invasive pathogens usually have symptoms that will resolve within several days without antimicrobials. In centers in which stool microbial testing with rapid molecu­lar assays is not available (yielding results within 5 hours), empiric treatment may be considered while the stool bacte­rial culture is incubating in certain patients: those with non–hospital-acquired diarrhea; those with moderate to severe fever, tenesmus, or bloody stools; and those with no suspicion of infection with STEC. It should also be consid­ered in patients who are immunocompromised or who have significant dehydration.


The oral drugs of choice for empiric treatment are the fluoroquinolones (eg, ciprofloxacin 500 mg, ofloxacin 400 mg, or levofloxacin 500 mg once daily) for 1–3 days. Alternatives include trimethoprim-sulfamethoxazole, 160/800 mg twice daily; or doxycycline, 100 mg twice daily. Macrolides and penicillins are no longer recommended because of widespread microbial resistance to these agents. Rifaximin (200 mg three times daily for 3 days) and azithromycin (1000 mg single dose or 500 mg daily for 3 days) are approved for empiric treatment of noninflamma­tory traveler’s diarrhea.

Specific antimicrobial treatment: Antibiotics are not recommended in patients with nontyphoid Salmonella, Campylobacter, STEC, Aeromonas, or Yersinia, except in severe disease, because they do not hasten recovery or reduce the period of fecal bacterial excretion. The infec­tious bacterial diarrheas for which treatment is recom­mended are shigellosis, cholera, extraintestinal salmonellosis, listeriosis, and C difficile. The parasitic infections for which treatment is indicated are amebiasis, giardiasis, cryptosporidiosis, cyclosporiasis, and Enterocy­tozoon bienusi infection.


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