metronidazole Nursing Considerations & Management

Drug Name

Generic Name : metronidazole

Brand Name: Apo-Metronidazole (CAN), Flagyl, Flagyl 375, Flagyl ER, Flagyl IV, MetroGel, MetroGel-Vaginal, NidaGel (CAN), Noritate, Protostat

Antibiotic, Antibacterial, Amebicide, Antiprotozoal

Pregnancy Category B 

Dosage & Route

Available forms : Tablets—250, 500 mg; ER tablets—750 mg; capsules—375 mg; powder for injection—500 mg; injection—500 mg/100 mL; lotion, cream, gel—0.75%; cream—1%; vaginal gel—0.75%



  • Amebiasis: 750 mg/tid PO for 5–10 days. (In amebic dysentery, combine with iodoquinol 650 mg PO tid for 20 days.)
  • Antibiotic-associated pseudomembranous colitis: 1–2 g/day PO for 7–10 days.
  • Gardnerella vaginalis: 500 mg bid PO for 7 days.
  • Giardiasis: 250 mg tid PO for 7 days.
  • Trichomoniasis: 2 g PO in 1 day (1-day treatment) or 250 mg tid PO for 7 days.


  • Anaerobic bacterial infection: 15 mg/kg IV infused over 1 hr; then 7.5 mg/kg infused over 1 hr q 6 hr for 7–10 days, not to exceed 4 g/day.
  • Prophylaxis: 15 mg/kg infused IV over 30–60 min and completed about 1 hr before surgery. Then 7.5 mg/kg infused over 30–60 min at 6- to 12-hr intervals after initial dose during the day of surgery only.

Topical (MetroGel)

  • Treatment of inflammatory papules, pustules, and erythema of rosacea: Apply and rub in a thin film twice daily, morning and evening, to entire affected areas after washing; results should be seen within 3 wk; treatment through 9 wk has been effective.

Vaginal (MetroGel-Vaginal)

  • In non-pregnant women: 1 applicatorful intravaginally one to two times/day for 5 days.
  • Anaerobic bacterial infection: Not recommended.
  • Amebiasis: 35–50 mg/kg/day PO in three doses for 10 days.
Therapeutic actions
  • Metronidazole is converted to reduction products that interact with DNA to cause destruction of helical DNA structure and strand leading to a protein synthesis inhibition and cell death in susceptible organisms. It is effective against a wide range of organisms including E. histolytica, T. vaginalis, Giardia, anaerobes e.g. Bacterioides sp, Fusobacterium sp, Clostridium sp, Peptococcus sp and Peptostreptococcus sp, and moderately active against Gardnerella sp and Campylobacter sp.
  • Acute infection with susceptible anaerobic bacteria
  • Acute intestinal amebiasis
  • Amebic liver abscess
  • Trichomoniasis (acute and partners of patients with acute infection)
  • Preoperative, intraoperative, postoperative prophylaxis for patients undergoing colorectal surgery
  • Topical application: Treatment of inflammatory papules, pustules, and erythema of rosacea
  • Unlabeled uses: Prophylaxis for patients undergoing gynecologic, abdominal surgery; hepatic encephalopathy; Crohn’s disease; antibiotic-associated pseudomembranous colitis; treatment of Gardnerella vaginalis, giardiasis (use recommended by the CDC)
Adverse effects
  • GI disturbances e.g. nausea, unpleasant metallic taste, vomiting, diarrhoea or constipation. Furred tongue, glossitis, and stomatitis due to overgrowth of Candida. Rarely, antibiotic-associated colitis. Weakness, dizziness, ataxia, headache, drowsiness, insomnia, changes in mood or mental state. Numbness or tingling in the extremities, epileptiform seizures (high doses or prolonged treatment). Transient leucopenia and thrombocytopenia. Hypersensitivity reactions. Urethral discomfort and darkening of urine. Raised liver enzyme values, cholestatic hepatitis, jaundice. Thrombophlebitis (IV).
  • Potentially Fatal: Anaphylaxis.
  • History of hypersensitivity to metronidazole or other nitroimidazole derivatives. Pregnancy (1st trimester) and lactation.
Nursing considerations
  • History: CNS or hepatic disease; candidiasis (moniliasis); blood dyscrasias; pregnancy; lactation
  • Physical: Reflexes, affect; skin lesions, color (with topical application); abdominal examination, liver palpation; urinalysis, CBC, LFTs
  • BLACK BOX WARNING: Avoid use unless necessary. Metronidazole may be carcinogenic.
  • Administer oral doses with food.
  • Apply topically (MetroGel) after cleansing the area. Advise patient that cosmetics may be used over the area after application.
  • Reduce dosage in hepatic disease.
Teaching points
  • Take full course of drug therapy; take the drug with food if GI upset occurs.
  • Do not drink alcohol (beverages or preparations containing alcohol, cough syrups); severe reactions may occur.
  • Your urine may be a darker color than usual; this is expected.
  • Refrain from sexual intercourse during treatment for trichomoniasis, unless partner wears a condom.
  • Apply the topical preparation by cleansing the area and then rubbing a thin film into the affected area. Avoid contact with the eyes. Cosmetics may be applied to the area after application.
  • You may experience these side effects: Dry mouth with strange metallic taste (frequent mouth care, sucking sugarless candies may help); nausea, vomiting, diarrhea (eat frequent small meals).
  • Report severe GI upset, dizziness, unusual fatigue or weakness, fever, chills.