Metronidazole 500mg/100ml infusion 100ml bags
Requires a prescription from a doctor or prescriber
Antibacterial drugs
Official documents, adverse reaction reporting, and safety monitoring
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Official medicine documents
Safety monitoring data
Yellow Card reports
The MHRA Yellow Card scheme collects reports of suspected side effects from healthcare professionals and patients. View the Drug Analysis Profile (iDAP) for real-world adverse reaction data.
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Suspected adverse reactions reported for Metronidazole
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Data from the MHRA Yellow Card scheme. A reported reaction does not necessarily mean the medicine caused it. Contains public sector information licensed under the Open Government Licence v3.0.
EudraVigilance
The European Medicines Agency (EMA) collects suspected adverse reaction reports from across the EU/EEA through the EudraVigilance system. Search for safety data on this medicine.
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Suspected adverse reactions reported for Metronidazole
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EudraVigilance data is published by the European Medicines Agency (EMA). A suspected adverse reaction is not necessarily caused by the medicine.
6 branded products available
Part of the Flagyl brand family (generic: Metronidazole)
MHRA licensed products
View all licensed products for Metronidazole on the MHRA register
Metronidazole 500mg/100ml infusion 100ml Viaflo bags
WHO defined daily dose (DDD)
1.5 gram
Not a recommended dose. The DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults. It is a statistical measure used for research and comparison purposes only.
Source: WHO Collaborating Centre for Drug Statistics Methodology, distributed via NHS dm+d BNF mapping files. Contains public sector information licensed under the Open Government Licence v3.0.
Therapeutically similar medicines
Similarity based on WHO Anatomical Therapeutic Chemical (ATC) classification and NHS BNF section grouping. Source data: NHS dm+d via TRUD (OGL v3.0), WHO ATC/DDD Index.
NHS prescribing volume and spending trends
Clinical guidelines and formulary information
British National Formulary
Metronidazole
Source: British National Formulary, NICE. Joint Formulary Committee. Contains public sector information licensed under the Open Government Licence v3.0.
NICE clinical guidance(12)
Clostridioides difficile infection: antimicrobial prescribing (NG199)
Crohn's disease: management (NG129)
Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management (CG184)
Human and animal bites: antimicrobial prescribing (NG184)
Diverticular disease: diagnosis and management (NG147)
Leg ulcer infection: antimicrobial prescribing (NG152)
Inflammatory lesions of papulopustular rosacea: ivermectin 10 mg/g cream (ESNM68)
Abortion care (NG140)
Cellulitis and erysipelas: antimicrobial prescribing (NG141)
Antimicrobial prescribing: oritavancin for acute bacterial skin and skin structure infections (ES39)
Neonatal infection: antibiotics for prevention and treatment (NG195)
Diabetic foot problems: prevention and management (NG19)
Source: National Institute for Health and Care Excellence (NICE). Contains public sector information licensed under the Open Government Licence v3.0.
Check stock at pharmacies and supply information
Pharmacy stock checkers
Search for this medicine at major UK pharmacy chains. These links open the retailer's own website — results depend on their current online catalogue.
Supply & product information
Official product databases and supply status monitoring
Pharmacy links redirect to the retailer's own search and do not represent real-time stock levels. emc (electronic medicines compendium) is operated by Datapharm Ltd. Shortage information sourced from NHS Specialist Pharmacy Service (SPS), sps.nhs.uk.
Codes for healthcare professionals and prescribing systems
These codes are used by healthcare IT systems and prescribers to identify this medicine.
NHS UK identifiers
Browse tools
SNOMED CT and dm+d codes from NHS TRUD (Technology Reference data Update Distribution), licensed under the Open Government Licence v3.0. BNF codes from NHS Business Services Authority (NHSBSA). ATC codes from the WHO Collaborating Centre for Drug Statistics Methodology (whocc.no).
Active and completed clinical studies from ClinicalTrials.gov
Source: ClinicalTrials.gov, a database of the U.S. National Library of Medicine (NLM), National Institutes of Health (NIH). Data accessed via ClinicalTrials.gov API v2. Trial information is provided for research purposes and does not constitute medical advice.
Pharmacology and chemical data from DrugBank
Key facts
Drug status
Approved
Major interactions
None known
Half-life
6 to 10 hours
Mechanism
The exact mechanism of action of metronidazole has not been fully established, h…
Food interactions
2 warnings
Human targets
None mapped
Data: DrugBank · CC BY-NC 4.0
Pharmacokinetics at a glance
Absorption
1 hour
[L7432]…
Half-life
500mg
[L7432]…
Protein binding
20%
[A181045][L7432]
Volume of distribution
0.51 to 1.1 L/kg
Metabolism
20%
Elimination
60 to 80%
[A181045][L3754]
Clearance
10 mL/min
[L7432]…
Pharmacokinetic data: DrugBank · CC BY-NC 4.0
[A181057][L49811]
The above anaerobic infections may occur on the skin and skin structures, the abdomen, the heart, reproductive organs, central nervous system, and the respiratory system. Some may also be present in the bloodstream in cases of septicemia. Common infections treated by metronidazole are Bacteroides species infections, Clostridium infections, and Fusobacterium infections, as well as Peptococcus and Peptostreptococcus infections.
[L3754]
Topical formulations of metronidazole are indicated for the treatment of inflammatory lesions of rosacea.
[L45166]
It is also used off-label in the treatment of Crohn's disease, as a prophylactic agent after surgery[A181039], and in the treatment of Helicobacter pylori infection.
[A181045]
It has also been studied in the prevention of preterm births and to treat periodontal disease.
[A1391][A181078]
Known interactions with other medications. Always consult a healthcare professional.
Showing 50 of 1003 interactions
The oral LD50 of metronidazole in rats is 5000 mg/kg [L7432]
Overdose information
Adverse effects that may be exaggerated with an overdose include peripheral neuropathy, central nervous system toxicity, seizures, disulfiram-like effect (if combined with alcohol) dark urine, a metallic taste in the mouth, nausea, epigastric discomfort, and vertigo, in addition to neutropenia.
[A181054][L7432]
There is no specific antidote for metronidazole overdose. Symptomatic and supportive treatment should be employed in addition to the administration of activated charcoal to remove the unabsorbed drug from the gastrointestinal tract. In addition to the above measures, contact the local poison control center for updated information on the management of a metronidazole overdose.
[L7432]
After administration, metronidazole enters cells by passive diffusion. Following this, ferredoxin or flavodoxin reduce its nitro group to nitro radicals.
The redox potential of the electron transport portions of anaerobic or microaerophilic microorganisms renders metronidazole selective to these organisms, which cause nitro group reduction, leading to the production of toxic metabolites. These include N-(2-hydroxyethyl) oxamic acid and acetamide, which may damage DNA of replicating organisms.[A181039]
A note on convulsions and neuropathy and carcinogenesis
It is important to be aware of the risk of peripheral neuropathy and convulsions associated with metronidazole, especially at higher doses. If convulsions or numbness of an extremity occur, discontinue the drug immediately.[L3754] Metronidazole has been found to be carcinogenic in mice and rats. The relevance to this effect in humans is unknown. It is advisable to only administer metronidazole when clinically necessary and only for its approved indications.[L7474]
How the body processes this drug — absorption, distribution, metabolism, and elimination
[L7432]
When a multiple-dose regimen of 500mg three times a day administered intravenously, steady-state concentrations were achieved within about 3 days and peak concentration was measured at 26 mg/L.
[L7432]
When administered orally in the tablet form, metronidazole is absorbed entirely absorbed, showing a bioavailability of greater than 90%.
[A181045]
One resource indicates that Cmax after a single oral dose of 500mg metronidazole ranges from 8 to 13 mg/L, with a Tmax of 25 minutes to 4 hours. The AUC following a single 500mg oral dose of metronidazole was 122 ± 10.3 mg/L • h.
[A181045]
A note on the absorption of topical preparations
Insignificant percutaneous absorption of metronidazole occurs after the application of 1% metronidazole cream topically. Healthy volunteers applied one 100 mg dose of 14C-labelled metronidazole 2% cream to unbroken skin.
After 12 hours, metronidazole was not detected in the plasma. Approximately 0.1% to 1% of the administered metronidazole was measured in the urine and feces.
[L7432]
[L7432]
Another resource indicates that the elimination half-life for metronidazole ranges from 6 to 10 hours.
[A181045]
[A181045][L7432]
[L7432]
Steady-state volume distribution of metronidazole in adults ranges from 0.51 to 1.1 L/kg. It attains 60 to 100% of plasma concentrations in various tissues, such as the central nervous system, however, is not measured in high concentrations in the placental tissue.
[A181045]
[A181045][A181144]
Unchanged metronidazole is found in the plasma along with small amounts of its 2- hydroxymethyl metabolite.
Several metabolites of metronidazole are found in the urine. They are primarily a product of side-chain oxidation in addition to glucuronide conjugation. Only 20% of the dose found in the urine is accounted for by unchanged metronidazole.
[L7432]
The two main oxidative metabolites of metronidazole are hydroxy and acetic acid metabolites.
[A181042][A181051]
[A181045][L3754]
[L7432]
The clearance of metronidazole in the kidneys is estimated at 10 mL/min/1.73 m2.
[L3754]
The total clearance from serum is about 2.1 to 6.4 L/h/kg.
[A181045]
Enzymes involved in drug metabolism — important for understanding drug interactions
Proteins that transport this drug across cell membranes
PMID:2897240 PMID:35970996 PMID:8898203 PMID:9038218 PMID:35507548
Catalyzes the flop of phospholipids from the cytoplasmic to the exoplasmic leaflet of the apical membrane. Participates mainly to the flop of phosphatidylcholine, phosphatidylethanolamine, beta-D-glucosylceramides and sphingomyelins .
PMID:8898203
Energy-dependent efflux pump responsible for decreased drug accumulation in multidrug-resistant cells PMID:2897240 PMID:35970996 PMID:9038218
ATC A02BD11
ATC P01AB52
ATC D06BX01
ATC A02BD03
ATC J01XD01
ATC J01RA04
ATC A02BD01
ATC J01RA14
ATC A02BD15
ATC J01RA03
ATC A01AB17
ATC G01AF20
ATC J01RA10
ATC A02BD02
ATC A02BD13
ATC G01AF01
ATC P01AB51
ATC A02BD08
ATC P01AB01
Chemical identifiers
CAS, UNII, InChI Key and database cross-references
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Chemical identifiers
CAS, UNII, InChI Key and database cross-references
Linked compound data from DrugBank Open Data (CC BY-NC 4.0)
Metronidazole
Additional database identifiers
Drugs Product Database (DPD)
9880
ChemSpider
4029
BindingDB
50375309
PDB
2MN
ZINC
ZINC000000113442
UniProt Accession
RDXA_HELPY
HUGO Gene Nomenclature Committee (HGNC)
HGNC:2622
GenAtlas
CYP2C8
GeneCards
CYP2C8
GenBank Gene Database
M17397
Guide to Pharmacology
1325
UniProt Accession
CP2C8_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:12530
GeneCards
UGT1A1
GenBank Gene Database
M57899
GenBank Protein Database
184473
Guide to Pharmacology
2990
UniProt Accession
UD11_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:2610
GenAtlas
CYP2A6
GeneCards
CYP2A6
GenBank Gene Database
X13897
Guide to Pharmacology
1321
UniProt Accession
CP2A6_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:2638
GenAtlas
CYP3A5
GeneCards
CYP3A5
GenBank Gene Database
J04813
GenBank Protein Database
181346
Guide to Pharmacology
1338
UniProt Accession
CP3A5_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:2640
GeneCards
CYP3A7
GenBank Gene Database
D00408
GenBank Protein Database
220149
UniProt Accession
CP3A7_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:2623
GenAtlas
CYP2C9
GeneCards
CYP2C9
GenBank Gene Database
AY341248
Guide to Pharmacology
1326
UniProt Accession
CP2C9_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:2637
GenAtlas
CYP3A4
GeneCards
CYP3A4
GenBank Gene Database
M18907
Guide to Pharmacology
1337
UniProt Accession
CP3A4_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:40
GenAtlas
ABCB1
GeneCards
ABCB1
GenBank Gene Database
M14758
GenBank Protein Database
307180
Guide to Pharmacology
768
UniProt Accession
MDR1_HUMAN
International reference pricing
Reference pricing from DrugBank. Prices are indicative and may not reflect current UK costs.
Source: DrugBank. Used under CC BY-NC 4.0 academic licence for non-commercial purposes.
Patent information
9 active patents, 7 expired
Source: DrugBank · CC BY-NC 4.0. Patent data sourced from national patent offices. Expiry dates may not reflect extensions, regulatory exclusivity periods, or legal challenges.
DrugBank citations
If you use DrugBank data in your research, please cite the following publications: