Hi there, A few years back when I was functioning around a level 6ish, I tried Coq10 for heavy leg/low circulation, and found it helped my fatigue somewhat. I tried it again last year when I was functioning around 1-3 and it gave me a headache. Now I'm at about a 4, I'd guess. I'm going to try taking just 15mg again and see if I get a headache or if my baseline improvement is enough to get the Coq10 tolerated again. I'll let folks know what happens in case any are curious. BTW I only take Enzymatic Therapy's CoQ10, any other brands have not really worked and have given me a headache.