Furosemide

Athanor · official

C₁₂H₁₁ClN₂O₅S · 330.74 g/mol

IUPAC name: 4-chloro-2-(furan-2-ylmethylamino)-5-sulfamoylbenzoic acid

Also called Lasix, frusemide, loop diuretic

Drugs Rings

Open in Athanor

Drawn from its SMILES with RDKit

DangerCauses skin irritation · Causes serious eye irritation · May cause respiratory irritation · Suspected of causing cancer · May damage fertility or the unborn child · Suspected of damaging fertility or the unborn child

Names and identifiers

IUPAC name: 4-chloro-2-(furan-2-ylmethylamino)-5-sulfamoylbenzoic acid
Synonyms: Lasix, frusemide, loop diuretic
+ 37 more
Frusemide, Furanthril, Furosemid, Errolon, Seguril, Transit, Aisemide, Beronald, Desdemin, Eutensin, Frusemin, Fuluvamide, Furanthryl, Furantril, Furesis, Fursemide, Lasilix, Lowpstron, Macasirool, Prefemin, Radonna, Rosemide, Trofurit, Fulsix, Katlex, Lasex, Frusetic, Fursemid, Logirene, Marsemide, Frusid, Mirfat, Oedemex, Furosedon, Urosemide, Aluzine, Dryptal
Molecular formula: C₁₂H₁₁ClN₂O₅S
Empirical formula: C₁₂H₁₁ClN₂O₅S
Molecular weight: 330.74 g/mol
Exact mass: 330.00772
CAS number: 54-31-9
PubChem CID: 3440
Canonical SMILES: C1=COC(=C1)CNC2=CC(=C(C=C2C(=O)O)S(=O)(=O)N)Cl
Isomeric SMILES: C1=COC(=C1)CNC2=CC(=C(C=C2C(=O)O)S(=O)(=O)N)Cl
InChI: InChI=1S/C12H11ClN2O5S/c13-9-5-10(15-6-7-2-1-3-20-7)8(12(16)17)4-11(9)21(14,18)19/h1-5,15H,6H2,(H,16,17)(H2,14,18,19)
InChIKey: ZZUFCTLCJUWOSV-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: White to off-white crystalline powder[2]
3 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Furosemide is an odorless white to slightly yellow crystalline powder. A diuretic drug. Almost tasteless. (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 White to off-white crystalline powder [2] Hazardous Substances Data Bank (HSDB)cites US NLM; DailyMed. Current Medical Information. Furosemide. US Natl Lib Med, Natl Inst Health, Health Human Serv. Available from, as of Apr 20, 2017: https://dailymed.nlm.nih.gov/dailymed/about.cfm
– Fine, white to slightly yellow, 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. 872
Odor: Odorless[2]
Melting point: 206 °C (403 °F) (decomposes) (NTP, 1992)[1]
Solubility in water: Slightly soluble in water[2]
6 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– less than 1 mg/mL at 73 °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.
– The sodium salt can be recrystallized from water; the solubility of the salt in water at room temperature is 6%. /Furosemide sodium salt/ [2] Hazardous Substances Data Bank (HSDB)cites Hropot M, Lang H-J; Diuretics. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2017). New York, NY: John Wiley & Sons. Online Posting Date: 15 Jun 2000
– In water, 73.1 mg/L at 30 °C [2] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 866
–shown Slightly soluble in water [2] Hazardous Substances Data Bank (HSDB)cites Scriabine A, Taylor DG; Antihypertensives. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2017). New York, NY: John Wiley & Sons. Online Posting Date: 15 Jun 2000
– Soluble in methanol, acetone, dilute NaOH [2] Hazardous Substances Data Bank (HSDB)cites Scriabine A, Taylor DG; Antihypertensives. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2017). New York, NY: John Wiley & Sons. Online Posting Date: 15 Jun 2000
– Freely soluble in alkali hydroxide [2] Hazardous Substances Data Bank (HSDB)cites McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 93. Bethesda, MD: American Society of Hospital Pharmacists, Inc., 1993 (Plus Supplements, 1993)., p. 1629
log P: log Kow = 2.03[2]
pKa: pKa = 3.9 (carboxyl)[2]
3 values
Only one source reports it.
Value As written Source
–shown pKa = 3.9 (carboxyl) [2] Hazardous Substances Data Bank (HSDB)cites Khan SJ, Ongerth JE; Chemosphere 54:355-67 (2004)
– pKa1 = 3.8 (carboxyl) [2] Hazardous Substances Data Bank (HSDB)cites Berthod A et al; Anal Chem 71: 879-88 (1999)
– pKa2 = 7.5 [2] Hazardous Substances Data Bank (HSDB)cites Berthod A et al; Anal Chem 71: 879-88 (1999)

Value	As written	Source
–	Furosemide is an odorless white to slightly yellow crystalline powder. A diuretic drug. Almost tasteless. (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	White to off-white crystalline powder	[2] Hazardous Substances Data Bank (HSDB)cites US NLM; DailyMed. Current Medical Information. Furosemide. US Natl Lib Med, Natl Inst Health, Health Human Serv. Available from, as of Apr 20, 2017: https://dailymed.nlm.nih.gov/dailymed/about.cfm
–	Fine, white to slightly yellow, 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. 872

Value	As written	Source
–	less than 1 mg/mL at 73 °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.
–	The sodium salt can be recrystallized from water; the solubility of the salt in water at room temperature is 6%. /Furosemide sodium salt/	[2] Hazardous Substances Data Bank (HSDB)cites Hropot M, Lang H-J; Diuretics. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2017). New York, NY: John Wiley & Sons. Online Posting Date: 15 Jun 2000
–	In water, 73.1 mg/L at 30 °C	[2] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 866
–shown	Slightly soluble in water	[2] Hazardous Substances Data Bank (HSDB)cites Scriabine A, Taylor DG; Antihypertensives. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2017). New York, NY: John Wiley & Sons. Online Posting Date: 15 Jun 2000
–	Soluble in methanol, acetone, dilute NaOH	[2] Hazardous Substances Data Bank (HSDB)cites Scriabine A, Taylor DG; Antihypertensives. Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (1999-2017). New York, NY: John Wiley & Sons. Online Posting Date: 15 Jun 2000
–	Freely soluble in alkali hydroxide	[2] Hazardous Substances Data Bank (HSDB)cites McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 93. Bethesda, MD: American Society of Hospital Pharmacists, Inc., 1993 (Plus Supplements, 1993)., p. 1629

Value	As written	Source
–shown	pKa = 3.9 (carboxyl)	[2] Hazardous Substances Data Bank (HSDB)cites Khan SJ, Ongerth JE; Chemosphere 54:355-67 (2004)
–	pKa1 = 3.8 (carboxyl)	[2] Hazardous Substances Data Bank (HSDB)cites Berthod A et al; Anal Chem 71: 879-88 (1999)
–	pKa2 = 7.5	[2] Hazardous Substances Data Bank (HSDB)cites Berthod A et al; Anal Chem 71: 879-88 (1999)

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: 21
Rings: 2
Aromatic rings: 2
Fraction sp³ carbons (Fsp3): 0.08
H-bond donors: 3
H-bond acceptors: 5 computed here · PubChem 7
Rotatable bonds: 5
TPSA (Å²): 122.6 computed here · PubChem 131
Formal charge: 0
XLogP3: 2 PubChem
Complexity: 481 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

C43.58%
H3.35%
Cl10.72%
N8.47%
O24.19%
S9.70%

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: 1.89 Crippen (Wildman and Crippen 1999)
log S (water solubility): -3.14 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.28 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 330.75
log P ≤ 5 (Crippen): 1.89
H-bond donors ≤ 5: 3
H-bond acceptors ≤ 10: 5

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: 240 company reports to ECHA. Source [3].

Harmful or irritant
Health hazard

H315Causes skin irritation (11.7% of reports)
H319Causes serious eye irritation (11.2% of reports)
H335May cause respiratory irritation (11.7% of reports)
H351Suspected of causing cancer (13.8% of reports)
H360May damage fertility or the unborn child (78.8% of reports)
H361Suspected of damaging fertility or the unborn child (14.2% of reports)

Precautionary statements: P203, P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P318, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501

View all classifications (3)

[3] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 0.4% (1 of 240) of reports.
[3] European Chemicals Agency (ECHA) · 240 reports · DangerH315, H319, H335, H351, H360, H361
[2] Hazardous Substances Data Bank (HSDB) · DangerH360

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

Keep container tightly closed in a dry and well-ventilated place.[2]
Furosemide injection should be stored at a temperature of 15-30 °C and protected from light; injections having a yellow color should not be used. Exposure of furosemide tablets to light may cause discoloration; discolored tablets should not be dispensed. Furosemide tablets should be stored and dispensed in well-closed, light-resistant containers at a controlled room temperature of 15-30 °C. ... The 20-mg tablets do not have a specific expiration dating period. Furosemide oral solutions should be stored at 15-30 °C and protected from light and freezing; once opened, unused portions of the oral[2]

Incompatibilities

Incompatible materials: Strong oxidizing agents.[2]
Furosemide is soluble in alkaline soln that is prepared as a mildly buffered alkaline product. It should not be mixed with acidic solns have a pH below 5.5. Furosemide may precipitate if combined with ascorbic acid, epinephrine, norepinephrine, or tetracycline. The acidic pH of aminoglycoside admixtures may cause transient cloudiness or frank precipitation if furosemide is added, depending on which aminoglycoside is used & the concn of the additives. Avoiding the admixture of furosemide & aminoglycosides has been recommended.[2]
Furosemide may precipitate if mixed with milrinone lactate infusions.[2]

Safety data sheets on the supplier’s page: Quality Control Solutions (QCS Standards), Combi-Blocks, InvivoChem.

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.