Ofloxacin and Ornidazole Tablets: Uses, Dose, Side Effects and Brands (2026)

• Updated 23 October 2026
• Reviewed by Sudhanshu Singhal
• 21 min read
• 39 sources

The MRP figures are Maximum Retail Prices shown by the e-pharmacy Tata 1mg on 23 October 2026, inclusive of applicable taxes, and 1mg notes that MRP may vary by batch, so these figures change over time and the price printed on the pack governs.

What is ofloxacin?

Ofloxacin is a fluoroquinolone antibiotic, while ornidazole and metronidazole are nitroimidazole antibiotics, and Indian pharmacies sell ofloxacin 200 mg alone, ofloxacin 200 mg with ornidazole 500 mg, and ofloxacin with metronidazole as a 60 ml oral suspension.

Ofloxacin on its own

Ofloxacin is classified as a fluoroquinolone (ATC code J01MA01) in the WHO AWaRe classification. The US label states that it works by inhibiting bacterial topoisomerase IV and DNA gyrase, enzymes that bacteria need for DNA replication, transcription, repair and recombination.

The UK SmPC describes it as a broad-spectrum fluoroquinolone active against Gram-positive and Gram-negative bacteria, with bacteria-killing activity that increases with the dose. It also records that resistance arises through mutations in DNA gyrase and topoisomerase IV, and through permeability barriers and efflux.

Ornidazole

Ornidazole is a nitroimidazole (ATC code P01AB03). The New Zealand data sheet states that it is effective against Trichomonas vaginalis, Entamoeba histolytica and Giardia lamblia, and also against certain anaerobic bacteria such as Bacteroides, Clostridium, Fusobacterium and anaerobic cocci. Amoebae and Giardia are protozoa, that is, single-celled parasites.

The Ethiopian SmPC for an Indian-made product explains that ornidazole is a 5-nitroimidazole whose nitro group is reduced inside the organism, and the resulting intermediate is believed to be the key component of how the organism is killed. About 90% of a dose is absorbed, with peak blood levels within 2 to 3 hours and a half-life of about 11 to 14 hours.

Metronidazole and simethicone in the suspensions

Metronidazole is also a nitroimidazole (ATC code P01AB01 for the oral form). The UK SmPC states that it is active against anaerobic bacteria and also against Trichomonas, Entamoeba histolytica, Giardia lamblia and Balantidium coli. The NHS describes it as an antibiotic that is available only on prescription.

Simethicone, which appears in some Indian suspensions, is not an antibiotic. Its US over-the-counter label gives the purpose as "Antigas" and the use as relief of pressure, bloating and fullness commonly referred to as gas.

Forms and strengths sold in India

• Ofloxacin 200 mg tablets, strip of 10.
• Ofloxacin 200 mg + ornidazole 500 mg tablets, strip of 10.
• Ofloxacin + metronidazole oral suspension, 60 ml bottle, at 50 mg + 100 mg per 5 ml and at 100 mg + 200 mg per 5 ml.

Vibcare also supplies an ofloxacin 50 mg + metronidazole 120 mg + simethicone 10 mg oral suspension in 60 ml bottles.

What is it used for?

The uses below are those stated in the official labels and national data sheets of each ingredient; labels differ by country and by product, and the pack in your hand and your doctor's prescription govern.

Ofloxacin — approved uses

The US label for Ofloxacin Tablets USP lists mild to moderate infections caused by susceptible bacteria in adults: acute bacterial exacerbation of chronic bronchitis, community-acquired pneumonia, uncomplicated skin and skin-structure infections, uncomplicated urethral and cervical gonorrhoea, non-gonococcal urethritis and cervicitis due to Chlamydia trachomatis, mixed urethral or cervical infection due to C. trachomatis with N. gonorrhoeae, acute pelvic inflammatory disease, uncomplicated cystitis, complicated urinary tract infections, and prostatitis due to E. coli.

The same US label reserves ofloxacin for acute bacterial exacerbation of chronic bronchitis and uncomplicated cystitis in patients who have no alternative treatment options, and says that where anaerobic bacteria are suspected an anaerobic agent should be added. The UK SmPC lists acute pyelonephritis and complicated urinary tract infection, non-gonococcal urethritis and cervicitis, gonococcal urethritis and cervicitis, acute exacerbation of COPD including bronchitis, community-acquired pneumonia and uncomplicated cystitis.

Both labels say the medicine is only for infections proven or strongly suspected to be bacterial. The US label adds that culture and susceptibility data should be considered. The UK SmPC adds that ofloxacin must only be prescribed when other antibiotics commonly recommended for the infection are inappropriate, because of the risk of prolonged, disabling and potentially irreversible reactions.

Ornidazole — approved uses

The New Zealand data sheet lists infections due to trichomonads, amoebae, Giardia lamblia and anaerobic bacteria: bacterial vaginosis, trichomoniasis, amoebiasis including amoebic dysentery and amoebic liver abscess, giardiasis, anaerobic bacterial infections such as septicaemia, meningitis, peritonitis, postoperative wound infections, puerperal sepsis, septic abortion and endometritis, and surgical prophylaxis. The Ethiopian SmPC lists trichomoniasis, amoebiasis, giardiasis, nonspecific vaginitis and surgical antibiotic prophylaxis.

Metronidazole — approved uses

The US Flagyl label lists symptomatic and asymptomatic trichomoniasis in women and their partners, acute intestinal amoebiasis and amoebic liver abscess, and serious anaerobic infections of the abdomen, skin, gynaecological tract, blood, bone and joint, central nervous system, lower respiratory tract and heart valves. The UK SmPC adds prophylaxis and treatment of anaerobic infections, urogenital trichomoniasis, bacterial vaginosis, giardiasis, acute ulcerative gingivitis, anaerobic leg ulcers and pressure sores, and acute dental infections.

What it does not treat

Antibiotics do not work for viral infections such as colds and flu and most coughs, and the NHS states that taking them when they are not needed can make them stop working in the future. Both the ofloxacin and metronidazole labels direct use only for infections proven or strongly suspected to be bacterial; the metronidazole label adds that this is to reduce the development of drug-resistant bacteria. No off-label use is described on this page.

Dose as stated in the labels

The regimens below are quoted from the labels exactly as they are written; the pack in your hand and your doctor's prescription govern, so always take the dose exactly as prescribed and never change it yourself. Prescription medicines must be taken only as prescribed by a doctor.

Ofloxacin tablets — US label (adults)

The US label gives the usual adult dose stated in the label for patients with creatinine clearance above 50 mL/min, dosed every 12 hours unless the table says otherwise.

For kidney or liver impairment the US label reduces the dose: after a normal first dose, a usual unit dose every 24 hours if creatinine clearance is 20 to 50 mL/min, half the usual unit dose every 24 hours if it is under 20 mL/min, and no more than 400 mg per day in severe liver disease.

Ofloxacin tablets — UK SmPC

The UK SmPC states 200 to 800 mg daily in adults, with up to 400 mg as a single dose preferably in the morning, and a maximum of 800 mg daily, given as 400 mg twice daily, for resistant or severe infection. By indication it gives 400 mg as a single dose for gonococcal urethritis and cervicitis, 200 to 400 mg daily for uncomplicated cystitis, 400 mg daily for pyelonephritis and complicated urinary tract infection, pneumonia and COPD flare, up to 400 mg twice daily if needed, and 400 mg daily for non-gonococcal urethritis and cervicitis. Treatment duration should not exceed 2 months.

The US label says the tablet may be taken with or without food. The UK SmPC says to swallow it whole with enough liquid, before or during meals. Neither label gives a paediatric dose: the UK SmPC contraindicates ofloxacin in children and growing adolescents, and the US label says safety and effectiveness under 18 years have not been established.

Ornidazole tablets — New Zealand data sheet

The New Zealand data sheet says ornidazole should be taken after meals and gives the following adult regimens: for trichomoniasis, three 500 mg tablets as a single evening dose, or one tablet morning and evening for 5 days, with the partner treated too; for amoebic dysentery, three tablets as one evening dose for 3 days, or four tablets in two doses for people over 60 kg; for all other forms of amoebiasis, one tablet morning and evening for 5 to 10 days; for giardiasis, three tablets as one evening dose for 1 to 2 days; and for surgical prophylaxis, 1,500 mg 12 hours before surgery followed by 500 mg every 12 hours for 3 to 5 days.

The same data sheet gives children's regimens by body weight and notes that the tablet cannot give the small doses some children need. It states that the dosing interval is doubled in severe liver impairment, that no change is needed in kidney impairment, and that an extra dose is given before haemodialysis. The Ethiopian SmPC gives the same regimens.

Metronidazole

The US Flagyl label gives 750 mg three times daily for 5 to 10 days for amoebiasis in adults, 35 to 50 mg per kg per day in three doses for 10 days in children, 375 mg twice daily for 7 days for trichomoniasis in women, and 7.5 mg per kg every 6 hours, not above 4 g in 24 hours, for anaerobic infections. The UK 400 mg SmPC gives 800 mg three times daily for 5 days for invasive intestinal amoebiasis, and several options for giardiasis including 2,000 mg once daily for 3 days. The ICMR 2019 guideline table for diarrhoea lists metronidazole 500 mg three times daily for 5 days for amoebiasis and 250 mg three times daily for 5 days for giardiasis in adults.

The combination tablets and suspensions

For the ofloxacin + ornidazole tablet and the ofloxacin + metronidazole suspension, follow the dose printed on the pack leaflet and the instruction given by the doctor who prescribed it.

Side effects

Common side effects are mostly stomach and nervous system complaints listed in the labels, while the serious effects that need urgent medical help are the ones in the fluoroquinolone and nitroimidazole warnings.

Common side effects

In the US ofloxacin trials the drug-related effects reported on multiple-dose treatment were nausea in 3% of patients, insomnia 3%, headache 1%, dizziness 1%, diarrhoea 1%, vomiting 1%, rash 1%, itching 1%, vaginitis 1% and altered taste 1%, and 4% of patients stopped treatment because of side effects. The UK SmPC lists dizziness, headache, abdominal pain, diarrhoea, nausea, vomiting, itching and rash as uncommon, meaning between 1 in 1,000 and 1 in 100.

For ornidazole, the New Zealand data sheet lists nausea, vomiting, diarrhoea, epigastric discomfort, dry mouth and loss of appetite as uncommon, and impaired taste and itching as rare. For metronidazole, the NHS lists feeling or being sick, diarrhoea, and a metallic taste in the mouth or a furry tongue as common effects, and the US label adds headache, loss of appetite, stomach cramps and constipation.

Serious side effects that need urgent medical help

The US ofloxacin label carries a boxed warning that fluoroquinolones can cause disabling and potentially irreversible reactions which may occur together: tendinitis and tendon rupture, peripheral neuropathy, and central nervous system effects. Stop the medicine immediately and avoid all fluoroquinolones if tendon pain or swelling, tingling or numbness, or confusion occur, and avoid ofloxacin in myasthenia gravis because it may worsen muscle weakness.

The same label records a higher tendon risk above 60 years of age, with corticosteroids, and in kidney, heart or lung transplant recipients, and notes that tendon damage can appear up to several months after treatment. It also warns about peripheral neuropathy that may be irreversible, psychiatric reactions, seizures, raised intracranial pressure, QT prolongation, allergic reactions after the first dose, low or high blood sugar, Clostridium difficile-associated diarrhoea that can appear over two months later, aortic aneurysm or dissection, sun sensitivity and reported liver damage.

The UK SmPC describes further prolonged and disabling reactions lasting months or years at a frequency of between 1 in 1,000 and 1 in 10,000: joint and limb pain, gait disturbance, neuropathies with tingling, fatigue, psychiatric symptoms such as anxiety and panic attacks, memory and concentration problems, and impaired hearing, vision, taste and smell. The UK SmPC notes that no pharmacological treatment is established for these reactions.

The US metronidazole label carries its own boxed warning that metronidazole was carcinogenic in mice and rats in studies, and advises avoiding unnecessary use of the drug. The most common metronidazole effects listed in the US label are nausea, headache, loss of appetite, vomiting, diarrhoea, stomach cramps, constipation and a metallic taste; serious effects include seizures, encephalopathy, peripheral neuropathy, optic neuropathy and severe skin reactions.

For ornidazole, the New Zealand data sheet lists very rare effects including sleepiness, headache, dizziness, tremor, poor coordination, seizures, fainting and sensory or mixed peripheral neuropathy, and says to stop treatment if ataxia, dizziness or confusion occur. For metronidazole, the NHS lists rare serious effects including yellow skin or eyes, blood problems, severe stomach pain, blurred or double vision, signs of meningitis, hallucinations or confusion, and anaphylaxis.

Who should not take it, and interactions

Do not take these medicines if you are allergic to any of their ingredients; the labels also list nerve, tendon, heart-rhythm, pregnancy and breastfeeding conditions in which they must not be used or need caution.

Contraindications

The UK ofloxacin SmPC contraindicates ofloxacin in allergy to ofloxacin or other fluoroquinolones, epilepsy or central nervous disorders that lower the seizure threshold, a history of fluoroquinolone-related tendon disorders, children and growing adolescents, pregnancy, breastfeeding, and latent or actual G6PD deficiency. The US label contraindicates it in hypersensitivity; its boxed warning says to avoid it in myasthenia gravis, and its warnings advise avoiding it in patients with known QT prolongation, uncorrected low potassium, or Class IA and III heart-rhythm drugs.

Ornidazole is contraindicated in allergy to ornidazole or other nitroimidazoles, with caution in central nervous system disease such as epilepsy, peripheral neuropathy and multiple sclerosis, and regular blood counts are advised in blood disorders or prolonged high-dose use. Metronidazole is contraindicated with alcohol or propylene-glycol products during treatment and for at least 3 days after, with disulfiram in the last 2 weeks, in Cockayne syndrome, and in trichomoniasis in the first trimester.

Key interactions

• Antacids containing calcium, magnesium or aluminium, sucralfate, iron, zinc and didanosine sharply reduce ofloxacin absorption; the labels say to separate them by 2 hours.
• Warfarin effect may rise with ofloxacin, ornidazole and metronidazole, so clotting should be monitored.
• NSAIDs may add to the seizure risk with ofloxacin, and corticosteroids add to the tendon risk.
• Diabetes medicines need blood sugar monitoring with ofloxacin, and QT-prolonging drugs such as Class IA and III antiarrhythmics, tricyclics, macrolides and antipsychotics need caution.
• Ornidazole may strengthen coumarin anticoagulants and prolongs the muscle-relaxant effect of vecuronium; caution is advised with lithium, cimetidine, phenytoin, phenobarbital and 5-fluorouracil.

Pregnancy and breastfeeding

The UK ofloxacin SmPC says ofloxacin must not be used in pregnancy and that breastfeeding should be stopped during treatment; the US label is Pregnancy Category C and says to decide between stopping nursing or stopping the drug. For ornidazole, the New Zealand and Ethiopian labels say no controlled studies exist in pregnant women, so it should not be prescribed in early pregnancy or to nursing mothers except when absolutely necessary. For metronidazole, the NHS says you may be able to use it in pregnancy if the doctor agrees, and short courses are advised while breastfeeding.

Alcohol

Alcohol must not be taken with metronidazole: the US label contraindicates it during treatment and for at least 3 days after, and the UK SmPC says to avoid it during treatment and for at least 48 hours after, because of a disulfiram-like reaction. The New Zealand ornidazole data sheet says alcohol must not be ingested during treatment or for at least 3 days after stopping; the Ethiopian SmPC notes that no disulfiram-like reaction has been reported with ornidazole but still advises avoiding alcohol with it. The UK ofloxacin SmPC says drowsiness and impaired skills may be enhanced by alcohol.

Rules in India

In India, the active ingredients ofloxacin, ornidazole and metronidazole are named in Schedule H of the Drugs and Cosmetics Rules, metronidazole is on the National List of Essential Medicines 2022, ofloxacin is in the WHO WATCH group, and the Ministry of Health and Family Welfare launched the Red Line campaign against self-medication with antibiotics, as reported in the cited PIB release.

The consolidated Drugs and Cosmetics Rules, 1945 name Ofloxacin, Ornidazole and Metronidazole in the Schedule H list. A Schedule H drug carries the Rx symbol and the warning "To be sold by retail on the prescription of a Registered Medical Practitioner only". A Press Information Bureau reply in the Lok Sabha on 10 February 2023 states that antibiotics are included in Schedules H and H1 of the Drugs Rules, 1945 and are sold only on a Registered Medical Practitioner's prescription.

The same PIB release describes the Red Line awareness campaign of the Ministry of Health and Family Welfare on antimicrobial resistance, which urges people not to take medicines marked with a red vertical line, including antibiotics, without a doctor's prescription. The NLEM 2022, notified under the DPCO 2013 on 11 November 2022, contains metronidazole tablets and oral liquid but does not list ofloxacin, ornidazole or simethicone. The current NPPA ceiling price order, S.O. 1575(E) of 25 March 2026 effective 1 April 2026, carries no entry for ofloxacin, ornidazole or simethicone.

In the WHO AWaRe classification 2025, ofloxacin is in the WATCH group, meaning a higher resistance potential and a key target of antibiotic stewardship, and it is not on the WHO Essential Medicines List 2025. Oral metronidazole and oral ornidazole are in the ACCESS group. UK and European regulators restrict fluoroquinolones to cases where other antibiotics are unsuitable, but those are not Indian rules.

Top brands in India

The table near the top of this page lists brands of ofloxacin 200 mg tablets, ofloxacin 200 mg + ornidazole 500 mg tablets and ofloxacin + metronidazole suspensions as seen on the e-pharmacy Tata 1mg on 23 October 2026, and no published sales-ranking source was found for these brands, so no brand here is called top-selling or best.

Ofloxacin 200 mg tablets in that list are Zanocin 200 and OFLox 200. The ofloxacin 200 mg + ornidazole 500 mg tablets are Oflox OZ, Zanocin OZ, Zenflox-OZ, Oflomac OZ and O2. Oflomac-M is an ofloxacin 50 mg + metronidazole 100 mg per 5 ml suspension, while New O2 and Diof-DS are ofloxacin 100 mg + metronidazole 200 mg per 5 ml suspensions.

The Vibcare range

Vibcare Pharma supplies 12 products in three compositions: ofloxacin 200 mg tablets, ofloxacin 200 mg + ornidazole 500 mg tablets, and an ofloxacin 50 mg + metronidazole 120 mg + simethicone 10 mg oral suspension in 60 ml bottles, sold under the Egaflox, Oflarb, Oflinor and Yetofol families across Vibcare divisions.

This range is available to Vibcare PCD franchise partners with monopoly rights in their district; see our Antibiotic PCD franchise and PCD pharma franchise pages.

Frequently asked questions

Sources

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