What are the medications and pain management options for possible appendicitis?

Medications for Possible Appendicitis

For possible appendicitis, initiate broad-spectrum antibiotics covering gram-negative and anaerobic organisms immediately upon clinical suspicion, and provide opioid analgesia without delay—pain control does not mask peritoneal signs or delay necessary intervention. 1, 2

Antibiotic Therapy

First-Line Antibiotic Regimens

For uncomplicated (non-perforated) appendicitis:

• Piperacillin-tazobactam 3.375g IV every 6 hours is the preferred single-agent therapy due to simplicity and comprehensive coverage 3
• Alternative: Cefotaxime 2g IV every 8 hours PLUS metronidazole 500mg IV every 6 hours 3
• Alternative: Ertapenem 1g IV every 24 hours as single-agent therapy 3

For complicated (perforated) appendicitis or abscess:

• Imipenem-cilastatin 1g IV every 8 hours for broader coverage 3
• Alternative: Meropenem 1g IV every 8 hours 3

Critical Antibiotic Selection Principles

Avoid these regimens due to resistance patterns:

• Do not use ampicillin-sulbactam due to E. coli resistance rates exceeding 20% 3
• Avoid cefotetan or clindamycin due to increasing Bacteroides fragilis resistance 3
• Avoid aminoglycosides in adults when equally effective alternatives exist due to toxicity concerns 3

Duration of Antibiotic Therapy

The duration depends on whether surgery is performed:

If appendectomy is performed:

• Single preoperative dose only for non-perforated appendicitis—no postoperative antibiotics needed if adequate source control achieved 1, 3
• Discontinue within 24 hours postoperatively for non-perforated cases 3
• For perforated appendicitis: 24 hours postoperatively if complete source control achieved, maximum 3-5 days even without complete source control 3

If non-operative management is chosen:

• Minimum 48 hours IV antibiotics followed by oral antibiotics for total 7-10 days 3
• For equivocal imaging or diagnostic uncertainty: minimum 3 days of antimicrobial therapy until symptoms resolve or definitive diagnosis established 1, 3

Pediatric Antibiotic Considerations

For children with non-perforated appendicitis:

• Single dose of second- or third-generation cephalosporin (cefoxitin or cefotetan) is sufficient 3

For perforated appendicitis in children:

• Ceftriaxone plus metronidazole is equally effective as anti-pseudomonal regimens with similar complication rates 4
• Use same adult regimens with weight-based dosing adjustments 3

Pain Management

Opioid Analgesia

Morphine sulfate IV is the standard opioid for appendicitis pain:

• Starting dose: 0.1 to 0.2 mg/kg IV every 4 hours as needed 5
• Administer slowly to avoid chest wall rigidity 5
• Must be given by providers familiar with respiratory depression management 5

Critical safety considerations:

• Dose carefully to avoid confusion between concentrations and mg/mL 5
• Monitor for respiratory depression, especially with concurrent CNS depressants 5
• Use reduced doses in elderly, debilitated, or patients with hepatic/renal impairment 5

Pain Medication Does Not Delay Diagnosis

Provide pain control as a priority:

• Opioids, NSAIDs, and acetaminophen do not result in delayed or unnecessary intervention 2
• Pain control should not be withheld due to concerns about masking peritoneal signs 2

Contraindications and Cautions

Morphine is contraindicated in:

• Known hypersensitivity to morphine 5
• Respiratory depression without resuscitative equipment 5
• Acute or severe bronchial asthma 5
• Suspected paralytic ileus 5

Use with caution:

• Morphine may obscure diagnosis or clinical course in acute abdominal conditions, but this should not prevent its use when appendicitis is suspected 5
• May cause sphincter of Oddi spasm 5

Management Algorithm for Suspected Appendicitis

When appendicitis is clinically suspected:

1. Initiate antibiotics immediately—do not delay for imaging confirmation 3
2. Provide adequate pain control with opioids 2
3. Obtain imaging (CT preferred, ultrasound alternative) 1
4. Continue antibiotics for minimum 3 days if imaging equivocal until symptoms resolve or definitive diagnosis made 1, 3

For confirmed appendicitis with abscess (>3 cm):

• Percutaneous drainage plus antibiotics if accessible 1
• Antibiotics should cover gram-negatives and anaerobes, adapted to culture sensitivities 1
• Clinical improvement expected within 3-5 days; if not, re-evaluate for surgical intervention 1

Common Pitfalls to Avoid

Do not delay antibiotic administration:

• Start empiric therapy as soon as appendicitis is clinically suspected, even before imaging or transfer 3

Do not continue antibiotics unnecessarily:

• For simple appendicitis post-appendectomy, continuing beyond 24 hours provides no benefit and increases resistance risk 3

Do not use narrow-spectrum regimens:

• Cephalosporins alone without anaerobic coverage are inadequate—appendicitis involves mixed aerobic-anaerobic flora requiring dual coverage 3

Do not withhold pain medication:

• Concerns about masking peritoneal signs are unfounded; pain control is a priority and does not delay necessary intervention 2