From the Guidelines
Methylene blue supplementation should be avoided in patients with G6PD deficiency, and its use requires caution in pregnant women, individuals with renal failure, and those taking serotonergic antidepressants, due to the risk of hemolysis, serotonin syndrome, and other adverse effects 1.
Key Considerations
- Methylene blue can induce hemolysis and worsen methemoglobinemia in patients with G6PD deficiency, making it essential to test for G6PD deficiency before administering the supplement 1.
- The supplement can interact with selective serotonin reuptake inhibitors and other serotonergic antidepressants, increasing the risk of serotonin syndrome 1.
- Methylene blue should be used with caution in pregnant women due to concerns about teratogenicity and possible intestinal atresia 1.
Dosage and Administration
- The usual starting dose of methylene blue for treating methemoglobinemia is 1–2 mg/kg (0.2 mL/kg of a 1% solution) infused intravenously over 3 to 5 minutes 1.
- The dose may be repeated at 1 mg/kg if methemoglobinemia does not significantly decrease within 30–60 minutes, but the risk of worsening methemoglobinemia increases with repeated doses 1.
Potential Benefits and Risks
- Methylene blue has potential benefits, including improved mitochondrial function, cognitive enhancement, and antioxidant properties, but its use as a supplement is not well established 1.
- The supplement can cause side effects, such as blue discoloration of urine and stool, mild nausea, and headaches, and its use requires careful consideration of the potential risks and benefits 1.
Recommendations
- Methylene blue supplementation should only be considered under the guidance of a healthcare provider, who can assess the individual's risk factors and medical history to determine the safest and most effective course of treatment 1.
From the Research
Effects of Methylene Blue Supplementation
The effects of Methylene Blue (methylthioninium chloride) supplementation can be categorized into several areas, including:
- Neuropsychiatric effects: Methylene Blue has been shown to have antidepressant, anxiolytic, and neuroprotective properties, as documented by both animal and human studies 2.
- Treatment of methemoglobinemia: Methylene Blue is used to treat methemoglobinemia at a dose of 1 to 2 mg/kg intravenously, and is generally safe with dose-related hemolytic effects 3.
- Diagnostic uses: Methylene Blue is used as a diagnostic substance in various procedures, including the detection of leaks or position of parathyroid corpuscles during surgery 4.
- Neuroprotection and memory enhancement: Methylene Blue has been shown to have neuroprotective effects and improve memory, particularly at low doses, by acting as an electron cycler in the mitochondrial electron transport chain 5, 6.
Potential Risks and Side Effects
The use of Methylene Blue also carries potential risks and side effects, including:
- Dose-dependent toxic effects, such as hemolysis, methemoglobinemia, nausea, vomiting, chest pain, dyspnea, and hypertension 4.
- Skin irritation and adverse inflammatory response in some individuals 4.
- Serotoninergic toxicity, which can manifest as neuromuscular hyperactivity 4.
- Special risks in individuals with G-6-PD deficiency, as well as those exposed to aniline dyes and dapsone 3.
Therapeutic Benefits
Methylene Blue has been shown to have therapeutic benefits in various conditions, including:
- Chronic cerebral hypoperfusion, where it may improve cognitive function and attenuate learning and memory deficits 6.
- Bipolar disorder, where it has been used to produce an antidepressant and anxiolytic effect without the risk of switching into mania 2.
- Neurodegenerative disorders, where its neuroprotective properties may be beneficial 2, 5.