What is the initial management for a patient presenting with diarrhea in primary care?

Primary Care Management of Diarrhea

Start with oral rehydration solution (ORS) as the cornerstone of treatment for any patient with diarrhea and signs of dehydration, reserving IV fluids only for severe dehydration with shock or altered mental status. 1

Immediate Assessment

Evaluate hydration status by examining:

• Skin turgor, mucous membrane moisture, and capillary refill time 2
• Vital signs including orthostatic blood pressure changes and pulse 2
• Mental status and urine output 2
• Body weight measurement 3

Classify dehydration severity:

• Mild (3-5% fluid deficit): Slightly dry mucous membranes, normal vital signs 3
• Moderate (6-9% fluid deficit): Sunken eyes, decreased skin turgor, tachycardia 3
• Severe (≥10% fluid deficit): Shock, poor perfusion, altered mental status - this is a medical emergency 3, 2

Rehydration Protocol

For Mild Dehydration (3-5% deficit):

• Administer reduced osmolarity ORS (50-90 mEq/L sodium) at 50 mL/kg over 2-4 hours 3, 1
• Start with small volumes (one teaspoon) using a syringe or medicine dropper, then gradually increase as tolerated 3
• Reassess after 2-4 hours; if still dehydrated, reestimate deficit and restart 3

For Moderate Dehydration (6-9% deficit):

• Increase ORS volume to 100 mL/kg over 2-4 hours using the same gradual approach 3, 1, 2
• Consider nasogastric administration if oral intake is not tolerated 1

For Severe Dehydration (≥10% deficit):

• Immediately initiate IV rehydration with 20 mL/kg boluses of lactated Ringer's or normal saline 3, 2
• Repeat boluses until pulse, perfusion, and mental status normalize 3
• May require two IV lines or alternate access (venous cutdown, femoral vein, intraosseous) 3
• Once consciousness returns, complete remaining deficit orally 3

For No Dehydration:

• Skip rehydration phase and proceed directly to maintenance therapy 3

Replace Ongoing Losses

• Administer 10 mL/kg ORS for each watery stool passed 3
• Give 2 mL/kg fluid for each vomiting episode 3

Dietary Management

• Continue breastfeeding on demand throughout the illness 3, 1, 2
• Resume age-appropriate normal diet immediately after rehydration or during rehydration 3, 1, 2
• For bottle-fed infants, use full-strength lactose-free or lactose-reduced formulas immediately upon rehydration 3
• If lactose-containing formula is used and diarrhea worsens significantly (not just low stool pH or reducing substances), temporarily reduce lactose 3

When to Order Diagnostic Testing

Most patients do NOT need laboratory workup or stool cultures. 1, 4 Reserve testing only for:

• Severe dehydration or severe illness 1, 4
• Persistent fever 1, 4
• Bloody or mucoid stools 1, 4
• Immunosuppression or immunosuppressive therapy 1, 5
• Suspected nosocomial infection or outbreak 1, 4

Antimicrobial Therapy

Do NOT give empiric antibiotics for acute watery diarrhea without recent international travel. 1

Exceptions where empiric treatment may be considered:

• Immunocompromised patients 1
• Ill-appearing young infants 1
• Suspected enteric fever 1

CRITICAL WARNING: Never give antibiotics for suspected STEC O157 or Shiga toxin-producing E. coli - this increases risk of hemolytic uremic syndrome. 1

Adjunctive Medications

Loperamide (for adults only):

• May be given to immunocompetent adults with acute watery diarrhea 1
• Absolute contraindications: Children <18 years, bloody diarrhea, fever, inflammatory diarrhea signs, mucous in stool 1, 2, 6
• Contraindicated in children <2 years due to respiratory depression and cardiac risks 2, 6
• Adult dosing: 4 mg initially, then 2 mg after each unformed stool, maximum 16 mg/day 6
• Never use as substitute for rehydration - only as ancillary therapy after adequate hydration 1

Ondansetron:

• May be given to children >4 years and adolescents with vomiting to facilitate oral rehydration 1

Probiotics:

• May be offered to reduce symptom severity and duration in immunocompetent patients 1

Zinc supplementation:

• Give 20 mg daily for 10-14 days in children 6 months to 5 years in areas with high zinc deficiency or malnutrition 1

Critical Pitfalls to Avoid

• Do NOT use commercial sports drinks or juices for rehydration - they have inappropriate electrolyte composition 1
• Do NOT treat asymptomatic contacts - advise infection control measures instead 1
• Do NOT use antimotility agents if fever, bloody stools, or mucous present 1, 2
• Do NOT give antibiotics for persistent watery diarrhea ≥14 days without workup 1

Red Flags Requiring Urgent Referral

Refer immediately to gastroenterology or emergency department if:

• Signs of severe dehydration or shock develop 2
• Fever with sepsis features 2
• Blood in stool with weight loss 5
• Palpable abdominal mass 5
• Clinical or laboratory signs of anemia 5