sulfadiazine at a glance
Medicine class
Short-acting sulfonamide antibiotic
How it is taken
Oral tablet swallowed with water
Important practical point
Good fluid intake helps reduce urinary crystal formation, unless fluids have been restricted
Name safety
Sulfadiazine is not sulfasalazine; confusing them can cause serious harm
What is sulfadiazine used for?
The selected product is for susceptible infections, rather than every infection caused by organisms in its laboratory spectrum.
Treatment of infections caused by susceptible bacteria, including selected streptococci, pneumococci, Nocardia and Haemophilus species; susceptibility among several Gram-negative organisms is variable.
It is not suitable for initial treatment of meningococcal meningitis; it has a restricted role only after sulfonamide susceptibility is established.
Non-licensed specialist use with pyrimethamine and folinic acid for toxoplasmosis, including serious, ocular or immunocompromised-patient disease.
How does sulfadiazine work?
Bacteria use para-aminobenzoic acid to make folate needed for growth. Sulfadiazine resembles this substance and competitively blocks bacterial folate production, mainly stopping bacteria from multiplying.
sulfadiazine preparations and strengths
Tablet
Route: Oral
Strengths: 500 mg
How to take sulfadiazine
Follow the pharmacy label and prescriber's instructions. Swallow tablets with a glass of water and maintain good fluid intake unless a clinician has advised fluid restriction. Do not stop treatment without discussing this with the prescriber.
Check that the label says sulfadiazine, not sulfasalazine.
Tell the prescriber if you have kidney problems.
Ask a pharmacist before starting non-prescription medicines or supplements.
sulfadiazine side effects
Common or expected effects
- Nausea or vomiting
- Loss of appetite
- Diarrhoea
- Sore or inflamed mouth
Get urgent medical advice
- A spreading, blistering or peeling rash, or sores of the mouth, eyes or genitals
- Breathing difficulty, facial or throat swelling, or collapse
- Sore throat, mouth ulcers, fever, repeated infections, unusual bruising or bleeding
- Yellow skin or eyes
- Severe or persistent diarrhoea
- Back or loin pain, blood in the urine, or markedly reduced urine output
- Seizures, severe confusion or other major neurological symptoms
sulfadiazine in pregnancy
Pregnancy requires an individual benefit–risk assessment. Product information advises against sulfonamides late in pregnancy because of possible newborn haemolysis. Evidence on congenital-malformation risk with sulfonamides is mixed. Specialist advice is particularly important when considering sulfadiazine for toxoplasmosis.
sulfadiazine while breastfeeding
Small amounts of sulfonamides enter breast milk. A specialist risk assessment is needed, particularly if the baby is premature, unwell, jaundiced, has raised bilirubin or may have G6PD deficiency, because haemolysis or bilirubin-related harm is a concern.
sulfadiazine interactions
Check the complete medication list before prescribing or taking sulfadiazine. Important interactions include:
Clozapine
Concurrent use is contraindicated because it may increase the risk of severe neutropenia or agranulocytosis.
Pyrimethamine
The combination is synergistic but increases the risk of folate-related megaloblastic anaemia and pancytopenia, requiring specialist oversight.
Warfarin and other coumarins
The anticoagulant effect may increase, raising bleeding risk and potentially requiring closer monitoring.
Methotrexate
Sulfadiazine may increase methotrexate effects and toxicity.
Common questions about sulfadiazine
Answers are fully visible for fast scanning and source review.
Is sulfadiazine the same as sulfasalazine?
No. Sulfadiazine is an anti-infective, while sulfasalazine is used for inflammatory conditions. Their similar names have caused serious medication errors.
Is sulfadiazine a penicillin antibiotic?
No. It belongs to the sulfonamide group and blocks microbial folate production.
Does sulfadiazine treat viral infections?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.