Rusty I had detox reations starting withing a couple of hours of my first dose of B2. Sinus draining (extreme), too tired to lift my arms, mild headache, increased fatigue. I definitely did less last week and couldn't walk the kids to the school bus. I slept 9 hours every night.
I took psyllium, pectin, charcoal all of which helped...or some of which. Who knows? Helped anyway!
Then I dropped back to a small dose and added in some manganese. I tried the bigger (12.5) doses again yesterday and had increased all over tiredness but nothing extreme. No headache - so perhaps the manganese helped there as aq suggested?
GL to all trying B2

)
Anne.
PS ETA I can now take 5000mg sublingual B12 with no head buzzing.