I saw a doctor who prescribed the glutathione to be taken in an inhaler sort of thing (nebulizer) and the hydroxycobalamine drops too. The B12 drops went into a nasal spray as well as into the inhaler.
I tried that therapy for about five full months along with the supplements she recommended. I got to see a nutritionist as well and in some ways felt I was more or less on a pretty good track, until... I ran out of money.
It was all too expensive for me and I had to stop. If money had been no object I probably would have continued the treatment and given it a go for a full year. I don't think five months was long enough to make too much of a dent in my condition unfortunately. It might have contributed to improved health more than I realise. I feel certain it didn't cause me any physical harm.
I'll watch this post of yours and see if there are any others out there who might say what their experience was.