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

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.

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 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.

In lab tests on mouse brain cells, methylene blue makes more hydrogen peroxide than azure I, but azure I is more efficient—it creates more of this chemical per bit of oxygen it uses. So even though it makes less overall, it’s more wasteful with oxygen.

Methylene blue makes heart cell power plants produce more harmful molecules when using one fuel (glutamate/malate), but less when using another (succinate), showing its effect depends on what the cell is burning.