About methylthioninium chloride
Thiazine dye; methemoglobinemia antidote
Used for
- Treatment of acquired methemoglobinemia when oxygen delivery is impaired
Usual adult dose
Usually 1 mg/kg by slow intravenous injection; may repeat once after one hour if needed.
Usual dose in children
Usually 1 mg/kg by slow intravenous injection; may repeat once after one hour if needed.
Common side effects
- Blue or green urine, skin, or other body fluids
- Nausea, vomiting, abdominal pain
- Headache, dizziness, confusion
- Injection-site pain or tissue injury if leakage occurs
Important warnings
- Can cause hemolysis, especially with glucose-6-phosphate dehydrogenase deficiency.
- May worsen methemoglobinemia at excessive doses.
- Can cause serotonin syndrome with serotonergic medicines.
- May interfere with pulse oximeter and laboratory readings.
Pregnancy
Use only when clearly necessary; potential fetal risks should be weighed against the urgency of treating methemoglobinemia.
Breastfeeding
Breastfeeding is generally paused during treatment and for a period afterward; follow product-specific guidance.
Interactions
- Serotonergic antidepressants and other serotonin-raising medicines: serotonin syndrome risk
- Opioids with serotonergic effects: serotonin syndrome risk
- Dapsone and other methemoglobin-forming drugs may complicate treatment
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.