Methylene blue can help mitochondria keep working when the first part of their energy system is broken, but it doesn't work at all when the second part is broken.

When the first step of energy production is blocked, methylene blue can help mitochondria make energy again—but when the second step is blocked, it can't help at all.

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.

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.

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