methylene blue

side effects h/a, Nausea, diarrhea, dizziness

Serios side effects - hemolytic anemia, g6pd deficiency, serotonin syndrome, hypersensitivity reactions / anaphylaxis / angioedema, interferes w/ pulse ox, hypotension, tachycardia, respiratory distress

Methylene Blue Dosing Guide Summary

Key Warnings

• Serotonin Syndrome: Avoid methylene blue with SSRIs, SNRIs, MAOIs, and opioids due to a risk of serotonin syndrome.
• Contraindications: Includes pregnancy, G6PD deficiency, intraspinal/subcutaneous use, and specific product-specific contraindications (eg, VueBlu in GI obstruction).

Indications and Doses

• Chromoendoscopy: Topical application, 0.1%-1% solution.
• Ifosfamide-induced Encephalopathy: 50 mg oral/IV every 4-8 hours as needed; secondary prophylaxis also available.
• Methemoglobinemia: IV 1-2 mg/kg over 5-30 minutes; repeat if needed up to 100 mg max dose.
• Onychomycosis: Off-label topical application of 2% solution bi-weekly.
• Sentinel Node Mapping in Breast Cancer: 5 mL of 1% solution injected once.
• Septic Shock: 1-2 mg/kg IV, up to 3 doses, with possible continuous infusion for refractory cases.
• Vasoplegia in Cardiac Surgery: 1-2 mg/kg IV bolus; continuous infusion options available.

Adverse Effects

• Common: Headache, myalgia, GI upset, injection-site reactions, dizziness, CNS depression, and skin/body fluid discoloration.
• Serious: Hemolysis (especially in G6PD deficiency), methemoglobinemia, hypotension, and CNS depression.

Special Considerations

• G6PD Deficiency: Use caution; contraindicated in certain formulations.
• Hepatic and Renal Impairment: Use with caution, and monitor for toxicities; dose adjustments may be necessary.
• Administration: IV injection over several minutes to reduce adverse effects; avoid subcutaneous or intrathecal use.

Monitoring

• Use methods beyond pulse oximetry to monitor oxygen saturation due to potential interference by methylene blue.

https://ccforum.biomedcentral.com/articles/10.1186/s13054-023-04397-7