What Causes Acute Gastroenteritis—and How Is It Treated?

Acute gastroenteritis is an inflammatory condition of the stomach and intestines, typically characterized by sudden onset of diarrhea, vomiting, abdominal cramps, and sometimes fever. It is most commonly caused by infectious agents—including viruses (such as norovirus and rotavirus), bacteria (like *Campylobacter*, *Salmonella*, *Escherichia coli*, and *Clostridioides difficile*), and occasionally parasites (e.g., *Giardia lamblia*). Non-infectious triggers—such as certain medications (e.g., antibiotics or NSAIDs), food intolerances, or ingestion of toxins—can also precipitate acute gastroenteritis, though these are less frequent.

Treatment focuses primarily on supportive care and symptom management. Oral rehydration therapy with balanced electrolyte solutions remains the cornerstone, especially in children and older adults who are at higher risk for dehydration. Intravenous fluids may be required in cases of severe dehydration, persistent vomiting, or inability to tolerate oral intake. Antimicrobial agents are generally not recommended for routine viral gastroenteritis and should be reserved for confirmed bacterial infections with systemic involvement—or in high-risk patients—based on clinical judgment and microbiologic testing. Antiemetics (e.g., ondansetron) may be considered in select cases to improve oral intake, while antidiarrheal agents like loperamide are used cautiously, avoided entirely in febrile or bloody diarrhea due to potential risk of complications such as toxic megacolon or prolonged bacterial shedding.

Prevention emphasizes hand hygiene, safe food handling, access to clean water, and vaccination—particularly rotavirus immunization in infants. Most cases resolve spontaneously within a few days; however, medical evaluation is warranted for red-flag symptoms including persistent high fever, hematochezia, signs of severe dehydration (e.g., tachycardia, hypotension, reduced urine output), or illness lasting longer than seven days.