Methylene blue

FDA label

Read the full label on DailyMed ↗

Renal Moderate or severe renal impairment (eGFR 15-59 mL/min/1.73m2): single 1 mg/kg dose; no adjustment for mild impairment (eGFR 60-89).

Hepatic Extensively hepatically metabolized; monitor patients with hepatic impairment longer for toxicity and drug interactions due to delayed clearance (no specific dose adjustment).

If methemoglobin remains >30% or symptoms persist, repeat 1 mg/kg at 1 hour; if unresolved after 2 doses, consider alternative interventions.

Instructions

• IV only - do not administer subcutaneously; ensure patent venous access
• May dilute in 50 mL of 5% Dextrose to reduce local pain (esp. pediatric); use immediately
• Do not dilute with sodium chloride solutions (chloride reduces solubility)
• Use methods other than pulse oximetry to assess oxygen saturation

Available strengths

• inj 5 mg/mL
• sol 1 g/100 mL

Contraindications

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency (risk of hemolytic anemia)

Cautions

• Serotonin syndrome with serotonergic drugs and opioids
• Hypersensitivity/anaphylaxis
• Lack of effectiveness (aniline/dapsone-induced methemoglobinemia; G6PD deficiency) - consider alternatives if no response after 2 doses
• Hemolytic anemia (onset may be delayed >=1 day; may require transfusion)
• Interferes with pulse oximetry and bispectral index (BIS) monitoring
• May impair ability to drive/operate machinery (confusion, dizziness, visual disturbance)
• Interferes with laboratory tests

Adverse reactions

• Headache
• Hypokalemia
• Diarrhea
• Hypomagnesemia
• Myoclonus
• Nausea
• Seizure-like phenomena

Pregnancy May cause fetal harm; intra-amniotic exposure associated with neonatal intestinal atresia and fetal death; animal developmental toxicity - use only if benefit justifies risk.

Lactation No data on presence in human milk; because of potential serious adverse reactions incl. genotoxicity, discontinue breastfeeding during and for up to 8 days after treatment.