Metronidazole: uses, appearance and warnings

Symptomatic Trichomoniasis. Metronidazole tablets USP is indicated for the treatment of T. vaginalis infection in females and males when the presence of the trichomonad has been confirmed by appropriate laboratory procedures (wet smears and/or cultures). Asymptomatic Trichomoniasis. Metronidazole tablets USP is indicated in the treatment of asymptomatic T. vaginalis infection in females when the organism is associated with endocervicitis, cervicitis, or cervical erosion. Since there is evidence that presence of the trichomonad can interfere with accurate assessment of abnormal cytological smears, additional smears should be performed after eradication of the parasite. Treatment of Asymptomatic Sexual Partners. T. vaginalis infection is a venereal disease. Therefore, asymptomatic sexual partners of treated patients should be treated simultaneously if the organism has been found to be present, in order to prevent reinfection of the partner. The decision as to whether to treat an asymptomatic male partner who has a negative culture or one for whom no culture has been attempted is an individual one. In making this decision, it should be noted that there is evidence that a woman may become reinfected if her sexual partner is not treated. Also, since there can be considerable difficulty in isolating the organism from the asymptomatic male carrier, negative smears and cultures cannot be relied upon in this regard. In any event, the sexual partner should be treated with metronidazole tablets USP in cases of reinfection. Amebiasis. Metronidazole tablets USP is indicated in the treatment of acute intestinal amebiasis (amebic dysentery) and amebic liver abscess. In amebic liver abscess, metronidazole tablets USP therapy does not obviate the need for aspiration or drainage of pus. Anaerobic Bacterial Infections. Metronidazole tablets USP is indicated in the treatment of serious infections caused by susceptible anaerobic bacteria. Indicated surgical procedures should be performed in conjunction with metronidazole tablets USP therapy. In a mixed aerobic and anaerobic infection, antimicrobials appropriate for the treatment of the aerobic infection should be used in addition to metronidazole tablets USP. 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, Peptococcus species, and Peptostreptococcus species. SKIN AND SKIN STRUCTURE INFECTIONS caused by Bacteroides species including the B. fragilis group, Clostridium species, Peptococcus species, Peptostreptococcus species, and Fusobacterium species. GYNECOLOGIC INFECTIONS, including endometritis, endomyometritis, tubo-ovarian abscess, and postsurgical vaginal cuff infection, caused by Bacteroides species including the B. fragilis group, Clostridium species, Peptococcus species, Peptostreptococcus species, and Fusobacterium 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. To reduce the development of drug-resistant bacteria and maintain the effectiveness of metronidazole tablets USP and other antibacterial drugs, metronidazole tablets USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. …

Metronidazole Tablets, USP 250 mg are blue, round, film coated tablet, debossed with "C80" on one side and plain on other side; supplied as bottles of 50 and 500. NDC Number Size 85742-024-24 bottle of 50 85742-024-25 bottle of 500 Metronidazole Tablets, USP 500 mg are blue, oblong, film coated, with "C81" on one side and plain on other side; supplied as bottles of 50 and 500. NDC Number Size 85742-025-24 bottle of 50 85742-025-25 bottle of 500 Storage and Stability: Store at 20° to 25°C (68° to 77° F) [See USP Controlled Room Temperature]. Protect from light. Rx only Manufactured by: Cadila Pharmaceuticals Limited 1389, Dholka, District - Ahmedabad, Gujarat State, INDIA Marketed and Distributed by: Kanchan Healthcare Inc 1 Gatehall Drive; Suite No. 202 Parsippany, NJ 07054 USA Revised: April 2026

Hypersensitivity Metronidazole tablets USP is contraindicated in patients with a prior history of hypersensitivity to metronidazole or other nitroimidazole derivatives. In patients with trichomoniasis, metronidazole tablets is contraindicated during the first trimester of pregnancy (see PRECAUTIONS ). Psychotic Reaction with Disulfiram Use of oral metronidazole is associated with psychotic reactions in alcoholic patients who were using disulfiram concurrently. Do not administer metronidazole to patients who have taken disulfiram within the last two weeks (see PRECAUTIONS , Drug Interactions ). Interaction with Alcohol Use of oral metronidazole is associated with a disulfiram-like reaction to alcohol, including abdominal cramps, nausea, vomiting, headaches, and flushing. Discontinue consumption of alcohol or products containing propylene glycol during and for at least three days after therapy with metronidazole (see PRECAUTIONS , Drug Interactions ). Cockayne Syndrome Metronidazole tablets are contraindicated in patients with Cockayne syndrome. Severe irreversible hepatotoxicity/acute liver failure with fatal outcomes have been reported after initiation of metronidazole in patients with Cockayne syndrome (see ADVERSE REACTIONS ).

Severe Cutaneous Adverse Reactions Severe cutaneous adverse reactions (SCARs) including toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP) have been reported with the use of metronidazole. Symptoms can be serious and potentially life threatening If symptoms or signs of SCARs develop, discontinue Metronidazole tablets USP immediately and institute appropriate therapy. Hypersensitivity Reactions Hypersensitivity reactions including severe cutaneous adverse reactions (SCARs) can be serious and potentially life threatening (see ADVERSE REACTIONS). Central and Peripheral Nervous System Effects Encephalopathy and peripheral neuropathy: Cases of encephalopathy and peripheral neuropathy (including optic neuropathy) have been reported with metronidazole. Encephalopathy has been reported in association with cerebellar toxicity characterized by ataxia, dizziness, and dysarthria. CNS lesions seen on MRI have been described in reports of encephalopathy. CNS symptoms are generally reversible within days to weeks upon discontinuation of metronidazole. CNS lesions seen on MRI have also been described as reversible. Peripheral neuropathy, mainly of sensory type has been reported and is characterized by numbness or paresthesia of an extremity. Convulsive seizures have been reported in patients treated with metronidazole. Aseptic meningitis: Cases of aseptic meningitis have been reported with metronidazole. Symptoms can occur within hours of dose administration and generally resolve after metronidazole therapy is discontinued. The appearance of abnormal neurologic signs and symptoms demands the prompt evaluation of the benefit/risk ratio of the continuation of therapy (see ADVERSE REACTIONS ).

The following reactions have been reported during treatment with metronidazole: Central Nervous System: The most serious adverse reactions reported in patients treated with metronidazole have been convulsive seizures, encephalopathy, aseptic meningitis, optic and peripheral neuropathy, the latter characterized mainly by numbness or paresthesia of an extremity. Since persistent peripheral neuropathy has been reported in some patients receiving prolonged administration of metronidazole, patients should be specifically warned about these reactions and should be told to stop the drug and report immediately to their physicians if any neurologic symptoms occur. In addition, patients have reported headache, syncope, dizziness, vertigo, incoordination, ataxia, tinnitus, hearing impairment, hearing loss, confusion, dysarthria, irritability, depression, weakness, and insomnia (see WARNINGS ). …

Disulfiram Psychotic reactions have been reported in alcoholic patients who are using metronidazole and disulfiram concurrently. Metronidazole should not be given to patients who have taken disulfiram within the last two weeks (see CONTRAINDICATIONS ). Alcoholic Beverages Abdominal cramps, nausea, vomiting, headaches, and flushing may occur if alcoholic beverages or products containing propylene glycol are consumed during or following metronidazole therapy (see CONTRAINDICATIONS ) . Warfarin and other Oral Anticoagulants Metronidazole has been reported to potentiate the anticoagulant effect of warfarin and other oral coumarin anticoagulants, resulting in a prolongation of prothrombin time. When metronidazole is prescribed for patients on this type of anticoagulant therapy, prothrombin time and INR should be carefully monitored. …