Sulfonamide antibiotic
Sulfadiazine
Adult dose
Dose: Toxoplasmosis: 1–1.5g PO QDS with pyrimethamine + folinic acid (specialist)
Route: PO
Frequency: QDS
Clinical pearls
- Toxoplasmosis (with pyrimethamine + folinic acid)
- Always co-prescribe folinic acid
Contraindications
- Sulfonamide hypersensitivity
- Severe renal/hepatic impairment
- Porphyria
- Pregnancy/breastfeeding (caution)
- G6PD deficiency
Side effects
- SJS/TEN
- Hepatotoxicity
- Cytopenias
- Crystalluria (maintain hydration)
- Hypersensitivity
- Photosensitivity
Interactions
- Methotrexate
- Warfarin
- Sulfonylureas
- Phenytoin
Monitoring
- FBC
- U&E
- LFTs
- Hydration
Reference: BNF; BHIVA; SmPC; https://bnf.nice.org.uk/drugs/sulfadiazine/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- Centor / McIsaac Score for Strep Pharyngitis · Throat
- FeverPAIN Score for Strep Throat · Throat
- Jarisch-Herxheimer Reaction Severity Assessment · Treatment Reactions
- PID Severity (CDC Diagnostic Criteria) · Gynaecological Infections
- Gustilo-Anderson Classification (Open Fractures) · Fracture Classification
- DRIP Score for Drug-Resistant Pneumonia · Pneumonia
Pathways
- Infective Endocarditis · ESC 2023 Infective Endocarditis Guidelines; NICE NG41
- Eczema Herpeticum · BAD; NICE CKS
- Suspected Bacterial Meningitis (Adult) · NICE NG240 (2024); NICE NG143 (paeds)
- Clostridioides difficile Colitis · NICE NG199 (2021); IDSA/SHEA 2021
- Returning Traveller — Fever · NaTHNaC; PHE; ESCMID 2018
- Malaria — Diagnosis & Management · PHE 2016; WHO 2023