GASTROINTESTINAL - Diarrhea, Clostridium difficile For relapses, treat again with metronidazole, possibly adding rifampin 300 mg PO Q12H × 10 days.
Metronidazole* (Flagyl^®) Generics available	Children: 30 mg/kg/day (max 1,000 mg/day) in divided doses every 6 hours for 7-10 days.		Food: Administer on empty stomach unless GI upset occurs, then with food.
Pregnancy: B; Lactation: Unsafe Tabs: 250 mg, 500 mg		Adult: 500 mg PO three times daily or 250 mg PO four times daily for 10-14 days.		Important side effects: Dizziness, headache, confusion, seizures, nausea, metallic taste, insomnia, paresthesias. Avoid alcohol.
Vancomycin* (Vancocin^®) Pregnancy: C; Lactation: Unk Caps: 125 mg, 250 mg Oral Sol: 1,000 mg/20 mL or 500 mg/6 mL		Children: 40 mg/kg/day (max 2000 mg/day) in divided doses PO every 6 hours for 10-14 days. Usual dose 125 mg every 6 hours. Adult: 125-500 mg PO every 6 hours for 10-14 days. Usual dose 125 mg every 6 hours.		Important side effects: Adverse effects of excessive systemic levels may include ototoxicity, nephrotoxicity, hematologic effects or hypersensitivity reactions. Therapeutic drug level monitoring is rarely necessary, but might be considered for patients receiving large oral doses in a setting of severe colitis and significant renal dysfunction.