What is the best treatment approach for a patient presenting with gastroenteritis?

Treatment of Gastroenteritis

The cornerstone of gastroenteritis treatment is oral rehydration therapy (ORS) for mild to moderate dehydration, with intravenous fluids reserved only for severe dehydration, shock, altered mental status, or failure of oral rehydration. 1

Initial Assessment and Hydration Strategy

Assess Dehydration Severity

The treatment approach is determined entirely by the degree of dehydration 1:

• Mild to moderate dehydration: ORS is the first-line treatment 1
• Severe dehydration: Intravenous isotonic crystalloid boluses are required 1
• Signs of shock, altered mental status, or ileus: Immediate IV rehydration is mandatory 1

Oral Rehydration Therapy (First-Line Treatment)

For mild to moderate dehydration, administer low-osmolarity ORS at specific volumes based on age and weight 1:

• Infants and children: 50-100 mL/kg over 3-4 hours 1
• Adolescents and adults (≥30 kg): 2-4 L over 3-4 hours 1

Ongoing replacement during maintenance 1:

• Children <10 kg: 60-120 mL ORS for each diarrheal stool or vomiting episode (up to ~500 mL/day) 1
• Children >10 kg: 120-240 mL ORS for each diarrheal stool or vomiting episode (up to ~1 L/day) 1
• Adolescents and adults: Ad libitum, up to ~2 L/day 1

Critical pitfall: Popular beverages like apple juice, Gatorade, and commercial soft drinks should NOT be used for rehydration as they lack appropriate electrolyte composition 1. Use commercially available ORS formulations such as Pedialyte, CeraLyte, or Enfalac Lytren 1.

Nasogastric ORS Administration

If the patient cannot tolerate oral intake but does not meet criteria for IV therapy, consider nasogastric administration of ORS in infants, children, and adults with moderate dehydration who are too weak or refuse to drink adequately 1.

Intravenous Rehydration (Severe Cases Only)

Administer IV isotonic crystalloid (lactated Ringer's or normal saline) for 1:

• Severe dehydration with signs of shock
• Altered mental status
• Failure of ORS therapy
• Ileus

Dosing for severe dehydration 1:

• Children, adolescents, and adults: 20 mL/kg body weight boluses until pulse, perfusion, and mental status normalize 1
• Malnourished infants: Smaller-volume frequent boluses of 10 mL/kg due to reduced cardiac capacity 1

Once stabilized, transition back to ORS to complete rehydration once the patient awakens, has no aspiration risk, and no evidence of ileus 1.

Nutritional Management

Resume normal age-appropriate diet immediately after rehydration is complete 1:

• Offer food every 3-4 hours 1
• Breastfed infants should continue nursing throughout the illness 1
• Children on lactose-containing formula can tolerate the same product in most instances—diluted formula offers no benefit 1
• Most infants completely recover despite potential mild transient lactose intolerance (10-14 days for rotavirus) 1

Antimicrobial Therapy

Antibiotics should NOT be routinely administered for viral gastroenteritis 1. The main risk is dehydration and electrolyte imbalance, not infection requiring antimicrobials 1.

Reserve antibiotics only for 1:

• Documented bacterial pathogens requiring treatment (based on stool culture/PCR)
• Severe illness with suspected bacterial superinfection
• Specific high-risk scenarios (immunocompromised, severe bloody diarrhea)

Symptomatic Treatment

Antiemetics

Ondansetron may be prescribed to prevent vomiting and improve tolerance of oral rehydration solutions in children with moderate dehydration 2.

Antimotility Agents

Loperamide should be used with extreme caution and only at prescribed dosages 3. The FDA label warns that higher-than-prescribed dosages can cause serious cardiac adverse reactions including QT prolongation, Torsades de Pointes, and cardiac arrest 3.

Contraindications and warnings for loperamide 3:

• Discontinue if no clinical improvement within 48 hours 3
• Contact healthcare provider if blood appears in stools, fever develops, or abdominal distention occurs 3
• Avoid in elderly patients taking QT-prolonging drugs 3
• Use caution with CYP3A4 inhibitors (itraconazole), CYP2C8 inhibitors (gemfibrozil), or P-glycoprotein inhibitors (quinidine, ritonavir) as these increase loperamide exposure and cardiac risk 3

For adults with Norwalk virus infection, bismuth subsalicylate reduced illness duration from 27 to 20 hours in one study 1.

Special Populations

Elderly Patients

Maintenance of good hydration is particularly important in elderly patients, especially those on diuretic medications 1.

Pregnant Women

Dehydration and electrolyte imbalance pose risks to pregnancy, but viral gastroenteritis agents do not constitute a particular threat to the fetus as viremic states do not occur 1.

Malnourished Patients

Severely undernourished patients require smaller-volume, frequent fluid boluses (10 mL/kg) due to reduced cardiac capacity 1.

Infection Control

Vigorous handwashing with soap, performed consistently at appropriate intervals, is necessary to control spread 1. Special handwashing products are not indicated as some commercial preparations are ineffective against rotavirus 1.

Thorough cleaning of environmental surfaces is required as a minimum to control viral gastroenteritis spread 1. Detergents should be used for laundering fecally contaminated linens and clothing 1.

When to Escalate Care

Hospitalization is indicated for 1, 2:

• Severe dehydration (>10% body weight loss or signs of shock) 2
• Failure to respond to oral rehydration therapy plus antiemetic 2
• Inability of caregiver to provide adequate oral rehydration 1
• Persistent vomiting preventing oral intake despite nasogastric or IV rehydration attempts 4

Common pitfall: Lack of access to medical care, rather than disease virulence, is a principal risk factor for death from gastroenteritis 1. Ensure appropriate follow-up for all discharged patients 4.