Side Effects
While generally safe at low doses, methylene blue can cause side effects, including:
- Nausea
- Headache
- Dizziness
- Blue discoloration of urine, skin, or mucous membranes
- Photosensitivity
- Potential serotonin syndrome when combined with SSRIs or MAO inhibitors
Contraindications
Methylene blue should not be used in the following scenarios:
- Pregnancy and Breastfeeding: MB can cross the placenta and is contraindicated in pregnant and breastfeeding women.
- G6PD Deficiency: It may cause hemolytic anemia in individuals with glucose-6-phosphate dehydrogenase deficiency.
- Combination with Serotonergic Drugs: There is a risk of serotonin syndrome.
- Severe Renal Impairment: MB is excreted renally and may accumulate in those with impaired kidney function (eGFR < 30)
- Viral and Tick-borne Infections: Caution due to risk of Herx reaction.