Cloxacillin
Cloxacillin is a penicillinase-resistant penicillin antibiotic used to treat bacterial infections, particularly those caused by staphylococci that are resistant to other penicillins. It works by inhibiting bacterial cell wall synthesis, making it effective against a narrow range of gram-positive organisms.
A penicillin antibiotic used to treat staphylococcal infections resistant to other penicillins.
Key facts at a glance
- ATC
- J01CF02
- RxNorm
- 2625
- Generic
- Cloxacillin
- Class
- atc-j01
- Brands
- Dry Clox
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- prefilled syringe, suspension, capsule
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 500mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 250mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg daily
- Maximum
- consult physician
- Frequency
- once daily
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
10 groupspregnancy
first trimesterstandard adult dose
use only if clearly needed and benefits outweigh potential risks
regular prenatal care
Use with caution and monitor for adverse effects.
pregnancy
second trimesterstandard adult dose
use only if clearly needed and benefits outweigh potential risks
regular prenatal care
Use with caution and monitor for adverse effects.
pregnancy
third trimesterstandard adult dose
use only if clearly needed and benefits outweigh potential risks
regular prenatal care and fetal monitoring
Use with caution and monitor for adverse effects.
lactation
breastfeedingstandard adult dose
considered compatible with breastfeeding
monitor infant for diarrhea or candidiasis
geriatric
elderlyadjust dose based on renal function
use standard dosing with renal function assessment
monitor renal function periodically
pediatric_age
neonatesdose based on weight and gestational age
use with caution in neonates especially premature
monitor renal function and for signs of toxicity
Use with caution and monitor for adverse effects.
pediatric_age
childrendose based on body weight 50-100mg/kg/day
standard pediatric dosing recommended
routine monitoring not required
renal_impairment
mild to moderateno adjustment needed for mild-moderate impairment
standard dosing for CrCl >30 mL/min
monitor renal function periodically
renal_impairment
severereduce dose or extend interval
reduce dose by 25-50% or extend dosing interval for CrCl <10 mL/min
frequent monitoring of renal function and drug levels if available
Use with caution and monitor for adverse effects.
hepatic_impairment
moderate to severeuse with caution, may need dose reduction
use with caution in moderate to severe hepatic impairment
monitor liver function tests
Use with caution and monitor for adverse effects.
Statistics and clinical data
Drug class
Beta-lactam antibiotic subclass
Common uses
Primary therapeutic indications
Mechanism of action
Pharmacodynamic classification
First approved
Initial market authorization
Cloxacillin is primarily used to treat skin and soft tissue infections, respiratory tract infections, osteomyelitis, and endocarditis caused by penicillinase-producing Staphylococcus aureus and other susceptible gram-positive bacteria.
Like other penicillins, cloxacillin inhibits the transpeptidase enzyme (penicillin-binding protein) responsible for cross-linking peptidoglycan chains in bacterial cell walls. Its unique feature is resistance to beta-lactamase (penicillinase), allowing it to remain effective against bacteria that have developed resistance to other penicillin antibiotics.
Cloxacillin is contraindicated in patients with penicillin hypersensitivity and may cause allergic reactions ranging from mild rash to anaphylaxis. Cross-reactivity with other beta-lactam antibiotics should be considered. Common side effects include gastrointestinal disturbances, and as with all antibiotics, it should only be used when a bacterial infection is confirmed or strongly suspected to prevent antibiotic resistance.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
WellAlly may earn a referral fee from linked resources at no extra cost to you. Editorial content is never influenced by commercial relationships.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy