Positives

• High-dose methylcobalamin comes up often in the Long COVID and ME/CFS overlap world, especially among people trying injections or large sublingual doses for fatigue, neuropathy, or suspected methylation problems. Reddit.

Negatives

• The main downside is overstimulation: some patients describe insomnia, anxiety, or feeling overmethylated rather than better when the dose or form is wrong for them. Reddit.

Hurdles & Side Effects

• This is rarely just "take more B12." Patients end up comparing methylcobalamin with other forms, adding folate or cofactors, and deciding between sublingual and injection protocols. Phoenix Rising.