1 May 2026Oral drugs

Sulfadiazine Oral: Dosing and Precautions

Sulfadiazine guidance for treatment and secondary prophylaxis of toxoplasmosis in immunodeficient patients.

Also searched as

Sulfadiazine

Prescription under medical supervision

Source reviewed

source date listed on the source page

Guide category

Oral drugs

Safety boundary

Prescription medicine information for clinician-guided use.

Kenza Health Hub presents this medicine page as structured health education. Check dose, route, interactions, pregnancy or breast-feeding considerations, and local protocol with a qualified clinician or pharmacist. Read our medical editorial policy.

This guide page is for structured reference only and does not replace a clinician, pharmacist, or emergency review. Dose choice, route choice, interactions, and safety decisions still need professional judgment.

Therapeutic action

Sulfonamide antibacterial.

Indications

Treatment and secondary prophylaxis of toxoplasmosis in immunodeficient patients, in combination with pyrimethamine.

Forms and strengths

500 mg tablet.

Dose and duration

Treatment of toxoplasmosis

Adult: 2 g 2 to 3 times daily for a minimum of 6 weeks.

Secondary prophylaxis of toxoplasmosis

Adult: 1 to 1.5 g 2 times daily, as long as necessary.

Contra-indications, adverse effects, precautions

Do not administer to sulfonamide-allergic patients or patients with severe renal or hepatic impairment.
May cause gastrointestinal disturbances, renal disorders, photosensitivity, megaloblastic anaemia due to folic acid deficiency, haemolytic anaemia in patients with G6PD deficiency, and allergic reactions that may be severe.
Adverse effects occur more frequently in patients with HIV infection.
Monitor blood count if possible.
Reduce the dose by half in patients with renal impairment.
Do not combine with methotrexate and phenytoin.
Administer calcium folinate systematically to prevent folic acid deficiency.
Drink a lot of liquid during treatment.
Pregnancy: no contra-indication, however avoid during the last month of pregnancy.
Breast-feeding: avoid if the infant is preterm, jaundiced, low birth weight, or under one month of age.

Source

MSF Essential drugs practical guidelines (January 2026)

This page combines source-derived medicine reference sections with Kenza editorial context, while leaving out the Storage and Remarks sections from the source batch.

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