Metronidazole

Athanor · official

C₆H₉N₃O₃ · 171.15 g/mol

IUPAC name: 2-(2-methyl-5-nitroimidazol-1-yl)ethanol

Also called Flagyl, nitroimidazole

Drugs Rings

Open in Athanor

Drawn from its SMILES with RDKit

DangerHarmful if swallowed · Harmful in contact with skin · Harmful if inhaled · Suspected of causing genetic defects · May cause cancer · Suspected of causing cancer · May causes damage to organs through prolonged or repeated exposure · Harmful to aquatic life with long lasting effects

Names and identifiers

IUPAC name: 2-(2-methyl-5-nitroimidazol-1-yl)ethanol
Synonyms: Flagyl, nitroimidazole, Metronidazol
+ 37 more
Gineflavir, 2-Methyl-5-nitroimidazole-1-ethanol, Deflamon, Orvagil, Trichazol, MetroGel, Sanatrichom, Anagiardil, Danizol, Meronidal, Metronidaz, Mexibol, Trichocide, Tricocet, Trivazol, Vagilen, Vagimid, Arilin, Clont, Klion, Bayer 5360, Metronidazolo, Acromona, Flagemona, Flagesol, Giatricol, Novonidazol, Protostat, Takimetol, Trichomol, Trichopol, Trikacide, Trikamon, Trikojol, Trikozol, Vertisal, Atrivyl
Molecular formula: C₆H₉N₃O₃
Empirical formula: C₂H₃NO
Molecular weight: 171.15 g/mol
Exact mass: 171.06439
CAS number: 443-48-1
PubChem CID: 4173
Canonical SMILES: CC1=NC=C(N1CCO)[N+](=O)[O-]
Isomeric SMILES: CC1=NC=C(N1CCO)[N+](=O)[O-]
InChI: InChI=1S/C6H9N3O3/c1-5-7-4-6(9(11)12)8(5)2-3-10/h4,10H,2-3H2,1H3
InChIKey: VAOCPAMSLUNLGC-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

TemperaturePressureDensity

Appearance: Metronidazole is a white to pale-yellow crystalline powder with a slight odor. Bitter and saline taste. pH (saturated aqueous solution) about 6.5. (NTP, 1992)[1]
2 values
From CAMEO Chemicals, the most authoritative source here.
Value As written Source
–shown Metronidazole is a white to pale-yellow crystalline powder with a slight odor. Bitter and saline taste. pH (saturated aqueous solution) about 6.5. (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
– WHITE TO PALE YELLOW CRYSTALS OR CRYSTALLINE POWDER [2] Hazardous Substances Data Bank (HSDB)cites Osol, A. and J.E. Hoover, et al. (eds.). Remington's Pharmaceutical Sciences. 15th ed. Easton, Pennsylvania: Mack Publishing Co., 1975., p. 1161
Odor: ODORLESS[2]
Melting point: 158 to 160 °C (316 to 320 °F, NTP 1992)[1]
Solubility in water: In water, 11,000 mg/L at 25 °C[2]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– less than 1 mg/mL at 68 °F (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
–shown In water, 11,000 mg/L at 25 °C [2] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan., Handbook of Aqueous Solubility Data: An Extensive Compilation of Aqueous Solubility Data for Organic Compounds Extracted from the AQUASOL dATAbASE. CRC Press LLC, Boca Raton, FL. 2003., p. 282
log P: log Kow = -0.02[2]
pKa: pKa = 2.38[2]

Value	As written	Source
–shown	Metronidazole is a white to pale-yellow crystalline powder with a slight odor. Bitter and saline taste. pH (saturated aqueous solution) about 6.5. (NTP, 1992)	[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
–	WHITE TO PALE YELLOW CRYSTALS OR CRYSTALLINE POWDER	[2] Hazardous Substances Data Bank (HSDB)cites Osol, A. and J.E. Hoover, et al. (eds.). Remington's Pharmaceutical Sciences. 15th ed. Easton, Pennsylvania: Mack Publishing Co., 1975., p. 1161

Value	As written	Source
–	less than 1 mg/mL at 68 °F (NTP, 1992)	[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
–shown	In water, 11,000 mg/L at 25 °C	[2] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan., Handbook of Aqueous Solubility Data: An Extensive Compilation of Aqueous Solubility Data for Organic Compounds Extracted from the AQUASOL dATAbASE. CRC Press LLC, Boca Raton, FL. 2003., p. 282

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms: 12
Rings: 1
Aromatic rings: 1
Fraction sp³ carbons (Fsp3): 0.5
H-bond donors: 1
H-bond acceptors: 4
Rotatable bonds: 3 computed here · PubChem 2
TPSA (Å²): 81.2 computed here · PubChem 83.9
Formal charge: 0
XLogP3: 0 PubChem
Complexity: 170 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C42.11%
H5.30%
N24.55%
O28.04%

Isotope pattern

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P: 0.09 Crippen (Wildman and Crippen 1999)
log S (water solubility): -1.07 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.65 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 171.16
log P ≤ 5 (Crippen): 0.09
H-bond donors ≤ 5: 1
H-bond acceptors ≤ 10: 4

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Danger

Most widely reported: 177 company reports to ECHA. Source [3].

Harmful or irritant
Health hazard

H302Harmful if swallowed (15.3% of reports)
H312Harmful in contact with skin (16.4% of reports)
H332Harmful if inhaled (16.9% of reports)
H341Suspected of causing genetic defects (53.7% of reports)
H350May cause cancer (49.7% of reports)
H351Suspected of causing cancer (34.5% of reports)
H373May causes damage to organs through prolonged or repeated exposure (29.4% of reports)
H412Harmful to aquatic life with long lasting effects (39.5% of reports)

Precautionary statements: P203, P260, P261, P264, P270, P271, P273, P280, P301+P317, P302+P352, P304+P340, P317, P318, P319, P321, P330, P362+P364, P405, P501

View all classifications (2)

[3] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 1.1% (2 of 177) of reports.
[3] European Chemicals Agency (ECHA) · 177 reports · DangerH302, H312, H332, H341, H350, H351, H373, H412

First aid

Eyes: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. Immediately transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. Skin: Immediately flood affected skin with water while removing and isolating all contaminated clothing.[1]

Storage

Precautions FOR "carcinogens": Storage site should be as close as practical to lab in which carcinogens are to be used, so that only small quantities required for ... Expt need to be carried. Carcinogens should be kept in only one section of cupboard, an explosion-proof refrigerator or freezer (depending on chemicophysical properties ...) that bears appropriate label. An inventory ... Should be kept, showing quantity of carcinogen & date it was acquired ... Facilities for dispensing ... Should be contiguous to storage area. (chemical Carcinogens)[2]

Incompatibilities

Because reconstituted metronidazole hydrochloride solution has a low pH, the solution may interact with aluminum resulting in a reddish-brown discoloration of the solution. Therefore, aluminum hub needles should not be used to reconstitute the drug or to transfer the reconstituted solution to the diluting fluid.[2]

Safety data sheets on the supplier’s page: eMolecules, TCI (Tokyo Chemical Industry), Veeprho.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

[1]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
[2]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[3]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[4]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[5]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[6]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[7]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
[8]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
·Literature on PubChem

Data last updated 2026-10-14.