When I started MSM (15g/day) + Zinc - I've got extremely terrible nightmares + the most strong headache I ever had in my life. It lasted 7 days and then I started to feel just awesome! So don't be afraid, that's detox - same thing as with Iodine. Good thing is that when I started Iodine some time later - I've got no bad detox symptoms at all, except few small eruptions on my back. MSM is awesome and it's great energy booster (you can feel strong energy hit starting from 8g/day) - but don't overdo it as it will deplete other vits/minerals needed to produce energy so you will end up with irritability / anxiety (from my own experience as well as from a friend of mine). I don't know what vits/minerals are working together with MSM to produce energy, if I find it - it will be a bomb! Until that time I advice to take 8-10g/day for not more than 10 days, then make a brake for 2 weeks (2g/day) and so on.