Reviewed on 5/23/2022

What Is Sulfadiazine and How Does It Work?

Sulfadiazine is a prescription medication used for preventing recurring rheumatic fever and for the treatment of toxoplasmosis

  • Sulfadiazine is available under the following different brand names: Silvadene

What Are Dosages of Sulfadiazine?

Adult dosage and pediatric


  • 500mg


Adult dosage

  • 2-4g Orally

Pediatric dosage

  • Children above 2months old
    • 75 mg/kg orally or  
    • 2 g/sq.meter Orally


Adult  dosage

  • 2-4 g/day divided 3-6times per day orally

Pediatric dosage

  • Children above 2 Months Old
  • 150 mg/kg/day divided every 4- 6 hours orally, or  
  • 4 g/sq. meter/day divided every 4 -6 hours orally
  • No more than 6 g/day

Prophylaxis of Recurrent Rheumatic Fever

Adult dosage

  • Adult above 30 kg: 1 g/day
  • Adult below 30 kg: 500 mg/day


Adult dosage

  • Given with Pyrimethamine & Folinic Acid
  • 1-1.5 g four times daily for 3-4 weeks
  • Prophylaxis (in patients with HIV): 0.5-1 g every 6hour with pyrimethamine (25-75 mg/day orally) & folinic acid (10-25 mg/day orally)

Pediatric dosage

  • 100-200 mg/kg/day divided every6hr orally into 3-4 weeks 
  • Infants below 2 months old: 25 mg/kg/day divided four-time daily orally
  • Prophylaxis (in patients with HIV): 85-120 mg/kg/day divided twice a day, three times a day, or four times a day with pyrimethamine (1 mg/kg or 15 mg/sq.meter daily-maximum dose 25 mg) & folinic acid (5 mg every third day)

Congenital Toxoplasmosis

Pediatric dosage

  • Given with pyrimethamine and folinic acid
  • 100 mg/kg/day divided every 6 hours orally for 12 months

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Sulfadiazine?

Common side effects of Sulfadiazine include:

  • loss of appetite
  • headache
  • nausea
  • vomiting
  • gastric distress/stomach upset
  • temporary, reversible male infertility
  • diarrhea
  • ringing in the ears (tinnitus)
  • dizziness
  • spinning sensation (vertigo)
  • unusual tiredness
  • white patches or sores inside the mouth or on your lips
  • sleep problems (insomnia)

Serious side effects of sulfasalazine include:

  • sun sensitivity
  • hearing changes
  • mental/mood changes
  • painful urination
  • blood in the urine
  • changes in the amount of urine
  • new lump or growth in the neck (goiter)
  • numbness or tingling of the hands or feet
  • signs of low blood sugar (e.g., hunger, cold sweat, blurred vision, weakness, fast heartbeat)
  • swollen glands

Rare side effects of Sulfadiazine include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Sulfadiazine?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Sulfadiazine has severe interactions with no other drugs
  • Sulfadiazine has serious interactions with at least 27 other drugs.
  • Sulfadiazine has moderate interactions with at least 54 other drugs.
  • Sulfadiazine has minor interactions with at least 47 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Sulfadiazine?


  • Should not be used for group A beta-hemolytic strep infections
  • Documented megaloblastic or folate deficiency anemia, obstructive uropathy

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Sulfadiazine?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Sulfadiazine?”


Pregnancy and Lactation

  • Use with caution if the benefits outweigh the risks during pregnancy
  • Lactation
    • Enters breast milk; risk of kernicterus if infant less than 2 months

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