Methylene blue makes mitochondria produce more hydrogen peroxide, but if you block a specific part of the energy chain (Complex III), that extra production stops—meaning methylene blue needs that part to work.

The more methylene blue you add, the more hydrogen peroxide the mitochondria make—up to 25 times more at the highest dose tested.

Two chemicals, methylene blue and azure I, make mouse brain cells produce a lot more hydrogen peroxide — over two and a half times more in some cases — when tested in a lab dish. This suggests they cause the tiny energy factories inside the cells to make more of this potentially harmful substance.

In mice, methylene blue fixes energy problems only if they’re caused by a specific broken part (Complex I)—not if another part (Complex III) is broken. This is different from what was seen in guinea pigs.

Unlike some toxins, methylene blue doesn’t make harmful free radicals in brain cells after they’ve been starved.

In a lab test with mouse brain cells, a chemical called methylene blue makes the energy-producing parts of the cells work harder without using energy to make ATP, while another chemical called azure I doesn’t do anything. This suggests methylene blue might be messing with how the cells normally control their energy production.