My ME/CFS specialist has recommended methylation treatment. I am homozygous MTHFR C677T amongst other things. I have been dragging my feet on starting this as I wanted to build up my immune system and be clear of viruses before I started. Well despite trying extra supplements to boost my immune system, I am still struggling with back to back viruses with hardly a break between them. I seem to be getting worse and I'm spending more time in bed. Yesterday I was reading "A Simple Explanation of the Glutathione/Methylation Depletion Theory of ME/CFS" by Rich Von Konynenburg. It talks about some people getting more and more infections over time. This is me. So after reading this and some prompting by @Daffodil I started methylation treatment this morning. My starting dose is 156.25mcg Hydroxocobalamin. I took this under my tongue this morning after breakfast. This is much less than my doctor recommended, but I do not tolerate meds well and I am firmly in the start low, go slow camp. I am going to take this by itself once a week to start with and see how it goes. Then I will add in methylfolate. I have had a busy morning with an appointment, so it is hard to tell whether how I am feeling is related to the HB12, but one thing I noticed which wouldn't be related to overdoing it is "clarity". I have a sense of alertness or clarity, like a fog has cleared. My instincts are that if I had too much of this I would be agitated or hyperactive mentally. I will see how it goes. I decided to put this information in a thread rather than a blog as I want to share my experiences with as many people as possible. I have benefitted so much from other people sharing on PR and want to pay that forward now. Best wishes, Andy.