Cefotaxime

Cefotaxime sodium

Antibiotic - 3rd Generation CephalosporinIVIMSCRegional perfusionNebulizationDogsCatsBirdsReptilesHorses

Also known as: Claforan · cefotaximum natricum · CTX · HR-756 · RU-24756

Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference

WHO critically important antibiotic — use with caution, avoid unnecessary prescription

22 mg/kg IV, IM or SC q8h for 7 days or less or 50 mg/kg IV or IM q12h for 7 days or lessIV, IM, SC· q8h or q12h· 7 days or less

Body weight— 🐕

Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.

Dosing by species

🌎 NA — North America🌍 EU — Europe

Dogs

Indication	Dose	Route	Frequency	Duration	Region
Soft tissue infections	22 mg/kg IV, IM or SC q8h for 7 days or less or 50 mg/kg IV or IM q12h for 7 days or less	IV, IM, SC	q8h or q12h	7 days or less	🌎 NA
Orthopedic infections	20-40 mg/kg IV, IM or SC q6-8h for 7 days or less	IV, IM, SC	q6-8h	7 days or less	🌎 NA
Severe bacteremia	20-80 mg/kg IV q6h or 10-50 mg/kg IV q4-6h for as long as necessary	IV	q4-6h	As long as necessary	🌎 NA
Susceptible infections	25-50 mg/kg IV, IM or SC q8h	IV, IM, SC	q8h	—	🌎 NA
Sepsis	20-80 mg/kg IV, IM q8h	IV, IM	q8h	—	🌎 NA
CNS infections (spinal cord)	25 mg-50 mg/kg IV, IM q8h	IV, IM	q8h	—	🌎 NA
Acute sepsis or serious susceptible infections	40-50 mg/kg	IV/IM/SC	q8h	Until clinical resolution	🌍 EU
Susceptible infections	10-20 mg/kg	IV/IM/SC	q12h	Until clinical resolution	🌍 EU

Acute sepsis or serious susceptible infections: Standard recommended dose.
Susceptible infections: Lower dose suggested by some authors to have good clinical efficacy.

Cats

Indication	Dose	Route	Frequency	Duration	Region
Severe bacteremia	20-80 mg/kg IV or IM q6h as long as necessary	IV, IM	q6h	As long as necessary	🌎 NA
Susceptible infections	25-50 mg/kg IV, IM or SC q8h	IV, IM, SC	q8h	—	🌎 NA
Sepsis	20-80 mg/kg IV, IM q8h	IV, IM	q8h	—	🌎 NA
CNS infections (spinal cord)	25 mg-50 mg/kg IV, IM q8h	IV, IM	q8h	—	🌎 NA
To prevent bacterial colonization of pancreas in severe pancreatitis, anorexia, or SIRS	50 mg/kg IM q8h	IM	q8h	—	🌎 NA
Acute sepsis or serious susceptible infections	40-50 mg/kg	IV/IM/SC	q8h	Until clinical resolution	🌍 EU

Acute sepsis or serious susceptible infections: Standard recommended dose.

Birds

Indication	Dose	Route	Frequency	Duration	Region
Susceptible infections (most birds)	50-100 mg/kg IM three times a day	IM	TID	—	🌎 NA
Bacterial infections, bacterial hepatitis	75-100 mg/kg IM or IV q4-8h	IM, IV	q4-8h	—	🌎 NA
Susceptible infections in ratites (young birds)	25 mg/kg IM 3 times daily	IM	TID	—	🌎 NA
Susceptible infections	75 mg/kg IM q8h	IM	q8h	—	🌎 NA

Susceptible infections (most birds): May be used with aminoglycosides, but nephrotoxicity may occur. Reconstituted vial good for 13 weeks if frozen.

Reptiles

Indication	Dose	Route	Frequency	Duration	Region
Susceptible infections	20-40 mg/kg IM once daily for 7-14 days	IM	q24h	7-14 days	🌎 NA
Susceptible infections in chelonians	20-40 mg/kg IM q24h	IM	q24h	—	🌎 NA
Nebulized antibiotic therapy	100 mg twice daily	Nebulization	BID	—	🌎 NA

Horses

Indication	Dose	Route	Frequency	Duration	Region
Susceptible infections in foals	40 mg/kg IV q6h	IV	q6h	—	🌎 NA
Meningitis in foals	40 mg/kg IV 3-4 times a day	IV	3-4 times a day	—	🌎 NA
Systemic therapy in foals	20-30 mg/kg IV or IM q6-8h	IV, IM	q6-8h	—	🌎 NA
Regional perfusion for adjunctive treatment of septic arthritis in foals	1 gram cefotaxime in 20 mL of saline. Tourniquet above and below joint. Inject antibiotic solution and leave tourniquet in place for 20 minutes.	Regional perfusion	Once	20 minutes	🌎 NA

Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.

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Overview

Cefotaxime is a third-generation parenteral cephalosporin antibiotic with a broad spectrum of activity against both gram-positive and gram-negative bacteria.

Key clinical features include:

Extended Gram-Negative Coverage: Highly effective against Enterobacteriaceae (e.g., Klebsiella, E. coli, Salmonella, Proteus).
Anaerobic Activity: Effective against many anaerobes including Bacteroides fragilis and Clostridium spp.
CNS Penetration: Unlike first- and most second-generation cephalosporins, cefotaxime achieves therapeutic concentrations in the cerebrospinal fluid (CSF) when the meninges are inflamed, making it a valuable option for bacterial meningitis and spinal cord infections.
Administration: Must be given parenterally (IV, IM, SC) as it is not appreciably absorbed orally. IV administration should be slow (over 3-5 minutes) to minimize adverse reactions.

Clinical Pearl: While it has excellent activity against many gram-negative aerobes, its efficacy against Pseudomonas aeruginosa is variable and often clinically disappointing. A 30-microgram cefotaxime disk should be used for Kirby-Bauer susceptibility testing.

Mechanism of action

Cefotaxime is a time-dependent, bactericidal antibiotic.

Mechanism: It binds to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall → inhibits the third and final stage of bacterial cell wall peptidoglycan synthesis → leads to cell lysis and death mediated by bacterial cell wall autolytic enzymes (autolysins).
Metabolism: It is partially metabolized in the liver to desacetylcefotaxime, an active metabolite that works synergistically with the parent compound to enhance antibacterial activity.

Safety & warnings

Contraindications

Patients with a documented history of hypersensitivity to cephalosporins

Adverse effects

Pain at the IM injection site
Thrombophlebitis (after IV administration)
Hypersensitivity reactions (rashes, fever, eosinophilia, anaphylaxis)
Antibiotic-associated diarrhea (alteration of gut flora)
Sterile abscesses or local tissue reactions
Rarely: Nephrotoxicity, neurotoxicity (at high doses), neutropenia, agranulocytosis, thrombocytopenia, hepatitis

Precautions

Use with caution in patients with documented hypersensitivity to other beta-lactam antibiotics (e.g., penicillins, carbapenems) due to potential cross-reactivity (estimated 1-15% in humans). Dosage adjustments may be necessary in patients with renal failure. May cause false-positive direct Coombs' tests, falsely elevated 17-ketosteroid urine values, and false-positive urine glucose determinations when using cupric sulfate solution tests (e.g., Clinitest).

Drug interactions

Aminoglycosides / Nephrotoxic drugs (e.g., amphotericin B)

Potential for additive nephrotoxicity. In vitro studies show synergistic antibacterial activity, but they must NOT be mixed in the same syringe or fluid bag.

Probenecid

Competitively blocks the renal tubular secretion of cefotaxime, significantly increasing its serum levels and prolonging its elimination half-life.

OxytetracyclineModerate

Bacteriostatic agents may antagonize the bactericidal activity of cephalosporins.

ErythromycinModerate

Bacteriostatic agents may antagonize the bactericidal activity of cephalosporins.

AminoglycosidesMinor

Synergistic antibacterial effect, but do not mix in the same syringe due to chemical incompatibility.

Amphotericin BMajor

Increased risk of nephrotoxicity.

FurosemideMajor

Loop diuretics may increase the risk of nephrotoxicity when used with cephalosporins.

Monitoring

Clinical efficacy (resolution of infection signs)
Renal function parameters (BUN, creatinine, urinalysis) in compromised patients or those on concurrent nephrotoxic drugs

Pharmacokinetics

Half-life

Cats~1 hourDogs45 minutes (IV), 50 minutes (IM), 103 minutes (SC)

Absorption

Not appreciably absorbed after oral administration; must be given parenterally. Bioavailability is approximately 87-98% after IM injection and ~100% after SC injection.

Distribution

Widely distributed in body tissues including bone, prostatic fluid, aqueous humor, bile, ascitic, and pleural fluids. Enters the CSF in therapeutic levels when meninges are inflamed. Crosses the placenta (activity in amniotic fluid equals or exceeds maternal serum) and distributes into milk in low concentrations. Protein binding is 13-40% in humans. Volume of distribution at steady state in dogs is 480 mL/kg.

Metabolism

Partially metabolized by the liver to desacetylcefotaxime, which exhibits some antibacterial activity. This is further degraded to inactive metabolites.

Elimination

Primarily excreted in the urine via tubular secretion. Total body clearance is 10.5 mL/min/kg in dogs and ~3 mL/min/kg in cats.

Overdose

Acute cephalosporin overdoses are unlikely to cause significant life-threatening problems. However, massive overdoses may exacerbate adverse effects, potentially leading to neurotoxicity (seizures, encephalopathy), nephrotoxicity, or severe gastrointestinal upset. Treatment should consist of standard supportive care and monitoring.

Available products

Formulations

Powder for injection
Premixed frozen injection solution

Human-labeled

Cefotaxime Sodium Powder for Injection: 500 mg, 1 g, 2 g, & 10 g in vials, bottles, infusion bottles & ADD-Vantage system vials
Cefotaxime Sodium for Injection: 1 g & 2 g in infusion bottles, & premixed, frozen 50 mL

Regulatory status

European Union✗ Not approvedPrescription onlyEMA

Classified as a highest priority critically important antibiotic. Use is heavily restricted to cases where no other appropriate licensed veterinary medicine exists and culture/susceptibility testing justifies its use.

United Kingdom✗ Not approvedPrescription onlyVMD

Subject to strict antimicrobial stewardship guidelines.

No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU

Storage & stability

Sterile powder for injection should be stored at temperatures < 30°C and protected from light. Commercially available frozen injections should be stored at < -20°C. Powder or solutions may darken depending on storage conditions, which may indicate a loss in potency. Cefotaxime is unstable in solutions with a pH > 7.5 (e.g., sodium bicarbonate).

Client information

Cefotaxime is a potent injectable antibiotic typically administered in a veterinary hospital setting to treat severe infections.

Administration: Because it is not absorbed through the GI tract, it must be given by injection (IV, IM, or under the skin).
Side Effects: Injections into the muscle can be painful. Watch the injection site for signs of swelling, redness, or pain.
Allergies: If your pet has had an allergic reaction to penicillins or other cephalosporins in the past, notify your veterinarian immediately.
GI Upset: As with many antibiotics, it can alter the normal bacteria in the gut, occasionally leading to diarrhea. Contact your veterinarian if diarrhea becomes severe or bloody.

VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.