What are the typical symptoms of acute gastroenteritis?

Symptoms of Acute Gastroenteritis

Acute gastroenteritis presents with sudden-onset watery diarrhea and vomiting, typically accompanied by nausea, abdominal cramps, and low-grade fever, with symptoms beginning 12–48 hours after exposure and resolving within 1–3 days in otherwise healthy individuals. 1

Core Clinical Features

The hallmark presentation includes both upper and lower gastrointestinal tract involvement:

• Diarrhea is characterized by frequent passage of loose, watery, non-bloody stools—the defining feature of gastroenteritis 1
• Vomiting occurs acutely at illness onset and typically resolves within 24 hours, though it may persist longer in young children and elderly patients 1, 2
• Nausea accompanies the vomiting and contributes to reduced oral intake 1
• Abdominal cramps and pain are common, ranging from mild discomfort to severe cramping 1

Constitutional Symptoms

• Low-grade fever may be present, though high fever (>38.5°C) suggests bacterial rather than viral etiology 1
• Body aches and myalgias frequently accompany the gastrointestinal symptoms, leading to the colloquial term "stomach flu" (though there is no biological association with influenza) 1
• Fatigue and malaise are typical constitutional features 3
• Headache may occur as part of the systemic illness 1

Signs of Dehydration

Volume depletion symptoms develop when fluid losses exceed intake:

• Thirst is an early indicator of mild dehydration 1
• Decreased urination with reduced urine output signals worsening fluid deficit 1, 4
• Orthostatic changes including tachycardia and blood pressure drops indicate moderate dehydration 1
• Lethargy and altered sensorium suggest severe dehydration requiring immediate intervention 1, 4
• Decreased skin turgor with prolonged tenting (>2 seconds) is a reliable physical finding in moderate-to-severe dehydration 4
• Dry mucous membranes and absent jugular venous pulsations are additional dehydration markers 1, 4

Typical Duration

• Vomiting typically lasts less than 24 hours in most cases 2
• Diarrhea persists for 3–7 days on average, though it may extend to 8 days in some patients 2
• Overall illness duration ranges from 1–3 days in otherwise healthy persons, with complete resolution usually occurring within one week 1, 2

Red-Flag Symptoms Requiring Immediate Evaluation

Certain features indicate potentially serious bacterial infection or complications:

• Bloody stools with fever and systemic toxicity suggest bacterial dysentery (Shigella, Salmonella, enterohemorrhagic E. coli) and risk of hemolytic uremic syndrome 1, 4, 3
• Bilious (green) vomiting may indicate intestinal obstruction and requires urgent surgical assessment 4
• Severe lethargy or altered consciousness signals severe dehydration (≥10% fluid deficit) constituting a medical emergency 4
• Prolonged symptoms beyond 7 days warrant investigation for bacterial, parasitic, or non-infectious causes 2, 3

Population-Specific Variations

• Young children and elderly persons may experience more prolonged courses lasting 4–6 days, with higher risk of severe dehydration and complications 1
• Immunocompromised patients can develop chronic diarrhea lasting weeks rather than days, with more severe symptoms 2, 3
• Hospitalized patients tend to have longer illness duration compared to community cases 1

Common Pitfall to Avoid

Do not dismiss gastroenteritis as trivial based on the typical self-limited course—approximately 10% of patients seek medical attention, and norovirus-associated deaths have been reported among elderly persons and in long-term care facility outbreaks, emphasizing the importance of recognizing high-risk populations and severe dehydration early. 1