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Metronidazole (Metronidazole) - Summary



Metronidazole has been shown to be carcinogenic in mice and rats (see PRECAUTIONS). Unnecessary use of the drug should be avoided. Its use should be reserved for the conditions described in the INDICATIONS AND USAGE section below.




Metronidazole Injection USP, sterile, is a parenteral dosage form of a synthetic antibacterial agent, 2-methyl-5-nitroimidazole-1-ethanol.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Metronidazole Injection USP and other antibacterial drugs, Metronidazole Injection USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.


Metronidazole Injection USP is indicated in the treatment of serious infections caused by susceptible anaerobic bacteria. Indicated surgical procedures should be performed in conjunction with Metronidazole Injection USP therapy. In a mixed aerobic and anaerobic infection, antibiotics appropriate for the treatment of the aerobic infection should be used in addition to Metronidazole Injection USP.

Metronidazole Injection USP is effective in Bacteroides fragilis infections resistant to clindamycin, chloramphenicol, and penicillin.

Intra-Abdominal Infections, including peritonitis, intra-abdominal abscess, and liver abscess, caused by Bacteroides species including the B. fragilis group (B. fragilis, B. distasonis, B. ovatus, B. thetaiotaomicron, B. vulgatus), Clostridium species, Eubacterium species, Peptostreptococcus species, and Peptococcus niger.

Skin and Skin Structure Infections caused by Bacteroides species including the B. fragilis group, Clostridium species, Peptococcus niger, Peptostreptococcus species, and Fusobacterium species.

Gynecologic Infections, including endometritis, endomyometritis, tuboovarian abscess, and post-surgical vaginal cuff infection, caused by Bacteroides species including the B. fragilis group, Clostridium species, Peptococcus niger, and Peptostreptococcus species.

Bacterial Septicemia caused by Bacteroides species including the B. fragilis group and Clostridium species.

Bone and Joint Infections, as adjunctive therapy, caused by Bacteroides species including the B. fragilis group.

Central Nervous System (CNS) Infections, including meningitis and brain abscess, caused by Bacteroides species including the B. fragilis group.

Lower Respiratory Tract Infections, including pneumonia, empyema, and lung abscess, caused by Bacteroides species including the B. fragilis group.

Endocarditis caused by Bacteroides species including the B. fragilis group.


The prophylactic administration of Metronidazole Injection USP preoperatively, intraoperatively, and postoperatively may reduce the incidence of postoperative infection in patients undergoing elective colorectal surgery which is classified as contaminated or potentially contaminated.

Prophylactic use of Metronidazole Injection USP should be discontinued within 12 hours after surgery. If there are signs of infection, specimens for cultures should be obtained for the identification of the causative organism(s) so that appropriate therapy may be given (see DOSAGE AND ADMINISTRATION).

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Published Studies Related to Metronidazole

Efficacy and safety of metronidazole for pulmonary multidrug-resistant tuberculosis. [2013]
Pulmonary lesions from active tuberculosis patients are thought to contain persistent, nonreplicating bacilli that arise from hypoxic stress... Newer nitroimidazoles with both aerobic and anaerobic activity, now in clinical trials, may increase the sterilizing potency of future treatment regimens.

Randomised clinical trial: vancomycin or metronidazole in patients with primary sclerosing cholangitis - a pilot study. [2013]
in patients with PSC... CONCLUSIONS: Both vancomycin and metronidazole demonstrated efficacy; however,

Clinical and microbiological benefits of metronidazole alone or with amoxicillin as adjuncts in the treatment of chronic periodontitis: a randomized placebo-controlled clinical trial. [2011.09]
AIM: To evaluate the effects of the adjunctive use of metronidazole (MTZ) or MTZ+amoxicillin (AMX) in the treatment of generalized chronic periodontitis (ChP)... CONCLUSION: The adjunctive use of MTZ+AMX offers short-term clinical and microbiological benefits, over SRP alone, in the treatment of non-smokers subjects with generalized ChP. The added benefits of MTZ were less evident. (c) 2011 John Wiley & Sons A/S.

Helicobacter pylori eradication with a capsule containing bismuth subcitrate potassium, metronidazole, and tetracycline given with omeprazole versus clarithromycin-based triple therapy: a randomised, open-label, non-inferiority, phase 3 trial. [2011.03.12]
BACKGROUND: Helicobacter pylori is associated with benign and malignant diseases of the upper gastrointestinal tract, and increasing antibiotic resistance has made alternative treatments necessary. Our aim was to assess the efficacy and safety of a new, single-capsule treatment versus the gold standard for H pylori eradication... INTERPRETATION: Quadruple therapy should be considered for first-line treatment in view of the rising prevalence of clarithromycin-resistant H pylori, especially since quadruple therapy provides superior eradication with similar safety and tolerability to standard therapy. FUNDING: Axcan Pharma Inc. Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Tinidazole vs metronidazole for the treatment of bacterial vaginosis. [2011.03]
OBJECTIVE: The purpose of this study was to compare the efficacy of 2 different doses of tinidazole with metronidazole for the treatment of bacterial vaginosis and to compare the side effects of the drugs... CONCLUSION: There were no differences in cure rates between metronidazole and either of the tinidazole dosing regimens that were studied. In addition, there were no important differences in the side-effect profiles of metronidazole and tinidazole. Copyright (c) 2011 Mosby, Inc. All rights reserved.

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Clinical Trials Related to Metronidazole

Efficacy of Metronidazole Versus Metronidazole and Rifampin in CDAD Treatment [Completed]
What is the difference between the use of one drug (Oral Metronidazole) versus the use of this same drug combined with another drug (Rifampin) in treatment of bacteria and infection-associated diarrhea in patients? This infection is an important cause of morbidity and mortality in both the community and hospitals, and the leading cause of hospital and chronic facility-acquired diarrhea. Research is important for the treatment of this infection. Patient care with use of two medication treatment regimens will be studied.

An Evaluation of the Cosmetic Appearance of Metronidazole Gel (MetroGel®) 1% [Completed]
The purpose of this study is to determine the cosmetic appearance of metronidazole gel (MetroGel®) 1% with commonly marketed facial foundations.

Safety and Efficacy Study to Compare IV CXA 101/Tazobactam and Metronidazole With Meropenem in Complicated Intraabdominal Infections [Recruiting]
A Phase 2, multicenter, prospective, randomized, double-blind study of CXA-101/ tazobactam (1000/500 mg q8h) and metronidazole (500 mg q8h) IV infusion vs. meropenem IV infusion (1000 mg q8h) and a matching saline placebo (q8h) in the treatment of cIAI in adult subjects. Dose adjustments for subjects with mild renal impairment are not necessary and subjects with more severe degrees of renal failure are excluded.

A Trial of Standard vs Half Dose Rabeprazole, Clarithromycin, Metronidazole and Amoxicillin in the Treatment of Helicobacter Pylori Infection [Recruiting]
The proposed study will test the hypothesis that H. pylori can be eradicated successfully (>85%) using half-or full-dose "concomitant" non-bismuth quadruple therapy regimen: rabeprazole, amoxicillin, clarithromycin and metronidazole twice daily for 7 days in patients with peptic ulcers and H. pylori related gastritis.

Two hundred patients from the outpatient department and the endoscopy unit at AUBMC will be enrolled in this open-label trial. Patients with positive CLO tests or urea breath tests, documenting H. pylori infection, will be randomized into one of two groups: Full dose or half dose the concomitant regimen, with 100 patients in each group. Compliance and side effects will be assessed, and a urea breath test will be done for all patients after 4 weeks of therapy completion to evaluate eradication rates. Success of therapy will be evaluated according to intent-to treat and per-protocol analyses.

A Safety, Tolerability and Pharmacokinetic Study of Two Formulations of Metronidazole Versus Immediate Release Metronidazole in Patient With C. Difficile Colitis [Recruiting]
Clostridium difficile bacteria can be a cause of significant diarrheal disease, particularly in people who have taken potent antibiotics. When C. difficile multiplies within the colon, it produces two toxins that cause inflammation and resultant abdominal pain, fever and diarrhea. Current treatment of mild to moderate disease is with immediate release metronidazole, an antibiotic that kills C. difficile. Dr. Reddy's Laboratories has developed a delayed release form of metronidazole to release just before the colon to increase the concentration of antibiotic in the colon to improve the effectiveness of metronidazole treatment and potentially to allow less whole body exposure to the antibiotic.

This study will measure the amount of metronidazole in the blood and stool of patients with C. difficile associated diarrhea (CDAD) to confirm that the new formulations are releasing the antibiotic as designed, immediately before the colon.

more trials >>

Reports of Suspected Metronidazole Side Effects

Vomiting (66)Nausea (56)Pyrexia (31)Toxic Encephalopathy (31)Dizziness (30)Diarrhoea (30)Dysarthria (29)Hepatotoxicity (27)Oedema (26)Drug Rash With Eosinophilia and Systemic Symptoms (25)more >>


Based on a total of 8 ratings/reviews, Metronidazole has an overall score of 5. The effectiveness score is 7.25 and the side effect score is 4. The scores are on ten point scale: 10 - best, 1 - worst. Below are selected reviews: the highest, the median and the lowest rated.

Metronidazole review by 18 year old male patient

Overall rating:  
Effectiveness:   Highly Effective
Side effects:   Extremely Severe Side Effects
Treatment Info
Condition / reason:   Tooth Abscess
Dosage & duration:   400 MG taken 3 times daily. for the period of 1 Week.
Other conditions:   N/A
Other drugs taken:   Amoxocillin
Reported Results
Benefits:   Personally, i found metronidazole to be an equivalent to a concentration drug, it severely improved my intelligence and my overall concentration, i realise now that this drug, as it may be depressing, a new chapter in my life. during the medication i received, i was severely depressed, however it got me thinking deeply towards why i was indeed depressed, and thus, i came to a solution. it completely destroyed the bacteria that was within my abscess and treated me within 3 days, and aided my mind alot. Within my experience with metronidazole, i have only to thank it for my A* papers and my mental health. With that i have only this to say: Take it, it aids the physical problems you have, and if your like me at all, with greater ambitions than any human can dream, This will make you realise all the problems you encounter, and it will cleanse you of your worries.
Side effects:   The side effects are the same as the benefits to me.
Comments:   400 MG 3 Times DAILY NOT to be taken with any alchohol. 7 Day period.


Metronidazole review by 30 year old male patient

Overall rating:  
Effectiveness:   Moderately Effective
Side effects:   Severe Side Effects
Treatment Info
Condition / reason:   Dog bite prophylaxis
Dosage & duration:   500mg taken 3x daily for the period of 8 days
Other conditions:   None
Other drugs taken:   Doxycycline HC
Reported Results
Benefits:   Apparently prevented wound infection, though efficacy of drug is questionable and causality cannot be established.
Side effects:   Side effects were severe. Consistent metallic taste in mouth, upset stomach, sleep difficulties, diarrhea, severe dizziness and anxiety. Transient dry mouth. General feeling of being "spacey" and unfocused.
Comments:   Took metronidazole to preclude infection after a puncture wound from a dog bite. Did not tolerate medication; ceased therapy after 8 days.


Metronidazole review by 31 year old female patient

Overall rating:  
Effectiveness:   Moderately Effective
Side effects:   Extremely Severe Side Effects
Treatment Info
Condition / reason:   Bacterial Lung Infection
Dosage & duration:   1 table 3x a day taken 6hrs for the period of 3
Other conditions:   none
Other drugs taken:   none
Reported Results
Benefits:   I was not able to take the drug long enough to know its benefits.
Side effects:   I took my first dose before bed one night. In the morning I woke with a cold sore and a very large ulcer on my tongue. I attributed this to the slight fever I had been running periodically. My tongue became increasingly sore. The second pill, later on that day, caused sever stomach pain, cramping, diarhea, nausea, and hot flashes. The oral pain remained about the same. I took the third, and last, dose that afternoon is the worst experience I have ever had with a drug. Immediately after taking the pill blisters began to appear wherever the pill had touched my skin. This included the entirety of my tongue, mouth, lips, and throat. I called the PA that had prescribed the drug and told her about the reaction. She told me to discontinue the drug immediately and that was a possible side effect of this drug. Had I any idea what it was going to be like, and the intense pain I would endure because of it, thenI would never have taken it.
Comments:   I took 3 pills. That is all.

See all Metronidazole reviews / ratings >>

Page last updated: 2014-11-30

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