Sulfadiazine
Pronunciation: (sul-fa-DYE-a-zeen).
- Generic name
- Sulfadiazine
- Brand names
- Sulfadiazine Tablets, USP
- Drug class
- Sulfonamide antibacterial
Availability and supply rules vary by country
Trade names by country: India
Australia: · Full directory
What Sulfadiazine is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how Sulfadiazine works
Sulfadiazine is a sulfonamide antibacterial that competitively inhibits dihydropteroate synthase, blocking bacterial (and Toxoplasma gondii) synthesis of dihydrofolic acid from para-aminobenzoic acid (PABA). This folic-acid-pathway blockade is bacteriostatic (and, against Toxoplasma, works best combined with pyrimethamine, which blocks a later step in the same pathway), inhibiting growth and replication of susceptible organisms. (1) (2)
What Sulfadiazine is used for
Toxoplasmosis encephalitis (with pyrimethamine)
Used as adjunctive (add-on) therapy with pyrimethamine for toxoplasmosis encephalitis, in patients with and without AIDS. (2)
Urinary tract infections (pyelonephritis, pyelitis, cystitis)
Caused by susceptible strains of E. coli, Klebsiella, Enterobacter, Staphylococcus aureus, Proteus mirabilis, and P. vulgaris, in the absence of obstructive uropathy or foreign bodies. Sulfadiazine should be used for urinary tract infections only after more soluble sulfonamides have been tried unsuccessfully. (2)
Chancroid, trachoma, inclusion conjunctivitis, nocardiosis
Chancroid, trachoma, inclusion conjunctivitis, nocardiosis (2)
Malaria due to chloroquine-resistant strains of Plasmodium falciparum (as adjunctive therapy)
Malaria due to chloroquine-resistant strains of Plasmodium falciparum (as adjunctive therapy) (2)
Prophylaxis of rheumatic fever recurrence
Prophylaxis of rheumatic fever recurrence (2)
Before taking Sulfadiazine
Do not take / not appropriate for
- "Hypersensitivity to sulfonamides. (Contraindication) (2)
- In infants less than 2 months of age... In pregnancy at term and during the nursing period, because sulfonamides cross the placenta and are excreted in breast milk and may cause kernicterus.". (Contraindication) (2)
Tell your clinician about
(2)How to take Sulfadiazine
- General Instructions: Take sulfadiazine exactly as prescribed. Drink a full 8-ounce glass of water with each dose and at frequent intervals throughout the day to help prevent kidney crystal formation.. Adult Dosing: Usual adult dose: an initial dose of 2-4 g, then a maintenance dose of 2-4 g per day divided into 3-6 doses.. Pediatric Dosing: Contraindicated in infants under 2 months of age, except as add-on therapy with pyrimethamine for congenital toxoplasmosis. For infants over 2 months and children: initially half the 24-hour dose, then a maintenance dose of 150 mg/kg or 4 g/m2 per day divided into 4-6 doses (maximum 6 g per 24 hours). For rheumatic fever prevention: 500 mg every 24 hours under 30 kg body weight; 1 g every 24 hours over 30 kg.. Administration: Swallow tablets with a full glass of water; maintain good fluid intake throughout treatment.. When To Seek Review: If you notice a sore throat, fever, paleness, unusual bruising/bleeding spots, or yellowing of the skin or eyes, seek medical advice promptly — these can be early signs of a serious blood disorder.. Storage: Store at 20-25°C (68-77°F), protected from moisture.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, contact your healthcare provider or pharmacist if you are unsure how to adjust your schedule. Do not take an extra dose to catch up.
Overdose
There is limited specific information on sulfadiazine overdose in the FDA label. Symptoms of sulfonamide overdose can include nausea, vomiting, dizziness, and, in severe cases, effects on blood counts or kidney function. In case of suspected overdose, seek emergency medical attention or contact a poison control center immediately. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Nausea, vomiting, abdominal pain, diarrhea, loss of appetite
Incidence: Reported gastrointestinal reactions; frequency not established
Headache, dizziness (vertigo), insomnia
Incidence: Reported central nervous system reactions; frequency not established
Signs of a blood disorder: sore throat, fever, paleness, unusual bruising or bleeding spots (purpura), or yellowing of the skin/eyes (jaundice)
What to do: Seek medical advice promptly — these need urgent clinician assessment. (2)
Skin reactions such as widespread rash, blistering, or peeling skin (possible Stevens-Johnson syndrome/epidermal necrolysis), hives, or facial/eye swelling
What to do: Seek immediate medical attention. (2)
Signs of a kidney problem: pain when passing urine, blood in urine, or reduced urine output (possible crystal formation or kidney stones)
What to do: Seek medical advice promptly. (2)
Serious warnings
Deaths have been associated with sulfonamide administration from hypersensitivity reactions, agranulocytosis, aplastic anemia, and other blood disorders — serious
Symptoms: Deaths have been associated with sulfonamide administration from hypersensitivity reactions, agranulocytosis, aplastic anemia, and other blood disorders. Sore throat, fever, paleness, purpura (bruising/bleeding spots), or jaundice may be early signs of a serious blood disorder — seek medical advice promptly if these occur.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindicated in patients with a known hypersensitivity to sulfonamides — serious
Symptoms: Contraindicated in patients with a known hypersensitivity to sulfonamides; in infants under 2 months of age (except as add-on therapy with pyrimethamine for congenital toxoplasmosis); and in pregnancy at term and during breastfeeding, because sulfonamides cross the placenta and pass into breast milk and may cause kernicterus (a serious form of newborn brain damage from high bilirubin levels).
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Sulfonamides should not be used to treat group A beta-hemolytic streptococcal infections (e — serious
Symptoms: Sulfonamides should not be used to treat group A beta-hemolytic streptococcal infections (e.g., strep throat) — they will not eradicate the bacteria and will not prevent complications such as rheumatic fever or kidney inflammation (glomerulonephritis).
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Use with caution in patients with impaired renal or hepatic function, severe allergy, or asthma — serious
Symptoms: Use with caution in patients with impaired renal or hepatic function, severe allergy, or asthma. Hemolysis (red blood cell breakdown) may occur in people deficient in glucose-6-phosphate dehydrogenase (G6PD) — this reaction is dose-related. Adequate fluid intake is required to help prevent crystals forming in urine and kidney stones.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Oral anticoagulants (e.g., warfarin), oral hypoglycemic agents (sulfonylureas), methotrexate | Sulfonamides such as sulfadiazine can displace these drugs from protein binding or affect their clearance, potentially enhancing their effects (increased bleeding risk with anticoagulants, low blood sugar with sulfonylureas, or increased methotrexate toxicity). Always tell your healthcare provider about all medicines and supplements you are taking. | (2) |
| Diuretics (acetazolamide, thiazides) and other goitrogen-related drugs | Sulfonamides bear certain chemical similarities to some goitrogens, diuretics, and oral hypoglycemic agents; goiter, increased urination, and low blood sugar have occurred rarely, and cross-sensitivity may exist between these drug classes. | (2) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Sulfadiazine is contraindicated in pregnancy at term, because sulfonamides cross the placenta and may cause kernicterus (a serious newborn brain condition) if given near delivery. Use earlier in pregnancy should only occur if directed by your treating clinician (for example, as part of toxoplasmosis treatment), weighing the risks and benefits for your specific situation. (2)
Breastfeeding
Sulfadiazine is contraindicated during breastfeeding, because sulfonamides pass into breast milk and may cause kernicterus in the nursing infant. Discuss any need for this medicine while breastfeeding with your healthcare provider. (2)
Children
Frequency: Divided into 4 to 6 doses every 24 hours (infants/children); rheumatic fever prevention is once daily.. Weight Based: Maintenance dose 150 mg/kg or 4 g/m2 per 24 hours (maximum 6 g/24 hours) for infants over 2 months and children; rheumatic fever prevention 500 mg/24 hours under 30 kg body weight, 1 g/24 hours over 30 kg.. Max Daily Dose: 6 g/24 hours (general pediatric dosing).. Max Single Dose: Determined by the divided-dose schedule above.. Age Restrictions: Contraindicated in infants under 2 months of age, except as adjunctive therapy with pyrimethamine for congenital toxoplasmosis. (2)
Renal_impairment
The FDA label does not provide a specific renal- or hepatic-impairment dose-reduction table for sulfadiazine. It advises that sulfonamides should be given with caution to patients with impaired renal or hepatic function, and that adequate fluid intake must be maintained to prevent crystals forming in the urine and kidney stones. Renal and hepatic status should be assessed and monitored by the prescriber, who may choose a different sulfonamide or adjust monitoring rather than following a fixed dose-reduction table. (2)
Hepatic_impairment
The FDA label does not provide a specific renal- or hepatic-impairment dose-reduction table for sulfadiazine. It advises that sulfonamides should be given with caution to patients with impaired renal or hepatic function, and that adequate fluid intake must be maintained to prevent crystals forming in the urine and kidney stones. Renal and hepatic status should be assessed and monitored by the prescriber, who may choose a different sulfonamide or adjust monitoring rather than following a fixed dose-reduction table. (2)
Monitoring
(2)Storage
Store at 20-25°C (68-77°F) (USP Controlled Room Temperature). Protect from moisture. Dispense and keep in a tight, light-resistant, child-resistant container. Keep out of reach of children.
Study the drug class: Sulfonamides
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General (US FDA label)
Indication: Toxoplasmosis encephalitis, susceptible urinary tract infections, and other approved indications
Dose summary: Usual adult dose: an initial dose of 2-4 g, then a maintenance dose of 2-4 g/day divided into 3-6 doses every 24 hours. Pediatric (over 2 months): initially half the 24-hour dose, then maintenance of 150 mg/kg or 4 g/m2 per 24 hours divided into 4-6 doses (maximum 6 g/24 hours). Contraindicated under 2 months of age except as adjunctive congenital-toxoplasmosis therapy with pyrimethamine.
Renal context: The FDA label does not give a specific renal dose-reduction table. It advises that sulfonamides be given with caution in patients with impaired renal function, since the frequency of renal complications (crystalluria, stone formation, toxic nephrosis) is considerably lower with more soluble sulfonamides; adequate fluid intake is required throughout treatment to reduce this risk. Renal function should be assessed and monitored by the prescriber. (1) (2)
Hepatic guidance
The FDA label does not give a specific hepatic dose-reduction table. It advises that sulfonamides be given with caution in patients with impaired hepatic function; hepatitis has been reported as a gastrointestinal-system adverse reaction. Hepatic function should be assessed and monitored by the prescriber.
Frequently asked questions
What is sulfadiazine used for?
Sulfadiazine tablets are used, together with pyrimethamine, to treat toxoplasmosis encephalitis, and alone for certain urinary tract infections, chancroid, trachoma, inclusion conjunctivitis, nocardiosis, and (as add-on therapy) chloroquine-resistant malaria, and to prevent rheumatic fever recurrence.
Is sulfadiazine the same as silver sulfadiazine cream?
No. Silver sulfadiazine is a different, topical product used on burns. This page covers oral sulfadiazine tablets, which are absorbed into the body and used for the infections listed above.
How should I take sulfadiazine?
Take it exactly as prescribed, and drink a full 8-ounce glass of water with each dose and frequently throughout the day, to help prevent kidney crystal formation.
What are the most serious risks with sulfadiazine?
Sulfonamides like sulfadiazine can rarely cause serious allergic reactions, severe skin reactions, and blood disorders that have been fatal in some cases. Seek medical advice promptly for a sore throat, fever, paleness, unusual bruising, or yellowing of the skin or eyes.
Can I take sulfadiazine if I am pregnant or breastfeeding?
Sulfadiazine is contraindicated in pregnancy at term and during breastfeeding because of the risk of kernicterus in the newborn/infant. Use earlier in pregnancy should only occur if your clinician specifically directs it. Discuss your situation with your healthcare provider.
Can infants take sulfadiazine?
Sulfadiazine is contraindicated in infants under 2 months of age, except as add-on therapy with pyrimethamine for congenital toxoplasmosis, under specialist direction.
What happens if I take too much sulfadiazine?
There is limited specific overdose information in the FDA label. Symptoms of sulfonamide overdose can include nausea, vomiting, dizziness, and, in severe cases, effects on blood counts or kidney function. If you suspect an overdose, seek immediate emergency medical attention or contact a poison control center.
Does sulfadiazine interact with other medicines?
Yes. It can enhance the effects of oral anticoagulants like warfarin, oral diabetes medicines (sulfonylureas), and methotrexate, and may cross-react with certain diuretics. Always tell your doctor and pharmacist about everything you take.
What is the mechanism of action of Sulfadiazine?
Sulfadiazine is a sulfonamide antibacterial that competitively inhibits dihydropteroate synthase, blocking bacterial (and Toxoplasma gondii) synthesis of dihydrofolic acid from para-aminobenzoic acid (PABA). This folic-acid-pathway blockade is bacteriostatic (and, against Toxoplasma, works best combined with pyrimethamine, which blocks a later step in the same pathway), inhibiting growth and replication of susceptible organisms. (1) (2)
What is the generic name of Sulfadiazine?
The generic name is Sulfadiazine. It is sold under brand names including Sulfadiazine Tablets, USP.
What class of drug is Sulfadiazine?
Sulfadiazine is classed as: Sulfonamide antibacterial.
References
- Sulfadiazine — internal overview referenceMedGuideGlobal · Global (internal) · accessed 2026-08-03 · source 1
- sulfADIAZINE Tablets, USP — FDA-approved prescribing information (Epic Pharma)U.S. FDA (via DailyMed) · United States · accessed 2026-08-07 · source 2
- SILVER SULFADIAZINE CREAM [ASCEND LABORATORIES, LLC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Sulfadiazine — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
- Silver Sulfadiazine — FDA approval record (Drugs@FDA NDA018810)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
- Sulfadiazine — RxNorm normalized drug concept (RXCUI 10171)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6
Brand names by country
Single-ingredient Sulfadiazine names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
India
- Silverex SSD10 g tube, 20 g tube, 240 g jar · Ranbaxy Laboratories (Sun Pharma)