Sulfamethazine
Sulfamethazine is a short-acting sulfonamide antibiotic used to treat various bacterial infections by inhibiting bacterial folic acid synthesis. It has been utilized in both human and veterinary medicine for conditions such as respiratory infections, urinary tract infections, and certain gastrointestinal infections.
Sulfamethazine is a sulfonamide antibiotic that treats bacterial infections by blocking folic acid production in bacteria.
Key facts at a glance
- ATC
- J01EB03
- RxNorm
- 10178
- Generic
- Sulfamethazine
- Class
- atc-j01
- Brands
- Sustain
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- tablet
- 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
9 groupspregnancy
first trimesteravoid if possible
avoid use during pregnancy unless benefits outweigh risks, particularly in near term
regular prenatal monitoring
Use with caution and monitor for adverse effects.
pregnancy
third trimesteravoid
do not use near term as sulfonamides may cause kernicterus in newborn
fetal monitoring and assessment of newborn
Use of this medication in this population requires careful consideration of risks and benefits.
lactation
breastfeedingdiscontinue breastfeeding or avoid drug
sulfonamides excreted in breast milk, may cause kernicterus in nursing infants especially premature
monitor infant for jaundice and signs of kernicterus
Use of this medication in this population requires careful consideration of risks and benefits.
pediatric_age
infants under 2 monthsavoid
do not use in newborns and infants under 2 months due to risk of kernicterus
monitor bilirubin levels
Use of this medication in this population requires careful consideration of risks and benefits.
pediatric_age
children 2 months and olderweight-based dosing
use appropriate weight-based dosing, ensure adequate hydration
monitor for adverse reactions and hydration status
geriatric
elderlyadjust based on renal function
use with caution due to age-related decline in renal and hepatic function
monitor renal function and adjust dose accordingly
Use with caution and monitor for adverse effects.
renal_impairment
mild to moderateadjust dose in severe impairment
dose adjustment may be required in severe renal impairment, ensure adequate hydration
monitor renal function and adjust dose accordingly
Use with caution and monitor for adverse effects.
renal_impairment
severesignificant dose reduction required
reduce dose significantly or avoid, monitor drug levels if available
frequent monitoring of renal function and drug levels
Use with caution and monitor for adverse effects.
hepatic_impairment
moderate to severeuse with caution
use with caution in hepatic impairment as drug is metabolized in liver
monitor liver function tests
Use with caution and monitor for adverse effects.
Statistics and clinical data
Commonly prescribed since
General prescribing information
Drug class
Drug class information
Common uses
Common therapeutic uses
Mechanism of action
Pharmacological mechanism
Sulfamethazine is used to treat various bacterial infections including respiratory tract infections, urinary tract infections, and certain gastrointestinal infections. It has historically been used in both human and veterinary medicine.
Sulfamethazine works as a sulfonamide antibiotic by inhibiting dihydropteroate synthase, an enzyme essential for bacterial folic acid synthesis. This blocks bacterial growth by preventing the production of folate, which bacteria need to replicate.
Like all sulfonamides, sulfamethazine can cause allergic reactions, particularly in patients with sulfa drug sensitivities. Common side effects may include gastrointestinal disturbances and skin reactions. Adequate hydration is recommended to prevent crystalluria. Resistance to sulfonamides has become increasingly common over time.
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
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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 24, 2026. · Read our editorial policy