What is the typical dose of Cefalexin (Cephalexin) and Flagyl (Metronidazole) for treating diverticulitis?

Dosage Regimens for Cefalexin and Metronidazole in Diverticulitis Treatment

For uncomplicated diverticulitis, the recommended dosage is cefalexin 500 mg orally four times daily plus metronidazole 500 mg orally three times daily for 7-10 days. 1

Patient Selection for Antibiotic Treatment

Antibiotics should be used selectively rather than routinely in diverticulitis. They are indicated for patients who:

• Have comorbidities or are frail
• Present with refractory symptoms or vomiting
• Have elevated inflammatory markers (CRP >140 mg/L or WBC >15 × 10^9/L)
• Show fluid collections or longer segments of inflammation on CT scan
• Are immunocompromised
• Are elderly (≥65 years)
• Are pregnant
• Have complicated diverticulitis 2

Dosage Details

Cefalexin (Cephalexin)

• Standard adult dose: 500 mg orally four times daily 3
• Total daily dosage range: 1-4g divided into multiple doses
• For severe infections, higher doses within the 1-4g daily range may be used 3

Metronidazole (Flagyl)

• Standard adult dose: 500 mg orally three times daily 2, 1
• Duration: 7-10 days (typically)

Treatment Approach

1. Initial management: Start with a clear liquid diet during the acute phase of diverticulitis 2
2. Advance diet: Progress diet as symptoms improve, typically within 3-5 days 2
3. Antibiotic administration: Begin antibiotics if indicated based on patient risk factors
4. Duration: Complete the 7-10 day course of antibiotics

Alternative Regimens

For patients who cannot tolerate oral medications:

• Intravenous options: Ceftriaxone plus metronidazole, or ampicillin/sulbactam 1
• Severe/complicated cases: Consider piperacillin-tazobactam 1

Monitoring and Follow-up

• Monitor for symptom improvement within 48-72 hours
• If symptoms worsen or fail to improve, consider imaging to rule out complications
• Outpatient treatment has been shown to be safe and effective for uncomplicated diverticulitis, with success rates over 92% 4

Important Considerations

• Metronidazole should be used cautiously with repeated or prolonged courses due to risk of cumulative and potentially irreversible neurotoxicity 2
• Cefalexin suspension should be refrigerated after mixing and may be kept for 14 days without significant loss of potency 3
• Recent evidence suggests that shorter antibiotic courses (as short as 1 day of IV antibiotics) may be effective for uncomplicated right colonic diverticulitis 5

Treatment Efficacy

Outpatient treatment with oral antibiotics has demonstrated safety and efficiency similar to inpatient treatment with intravenous antibiotics, with no significant statistical differences in outcomes (p = 0.86) 6. This approach also produces an important reduction in healthcare expenses, saving approximately €1,600 per patient 6.