I was just diagnosed and took my first dose of 25 mcg of levothyroxine and a large dose of vitamin D on Friday. I became so I'll that I had to leave work. I had a severe headache along with feeling drugged or severe brain fog along with tiredness, flushing, tiredness. I have never felt this bad. I don't know which med caused this but either way I can't go through it again. My doc wants me to try to take it again. Im thinking second opinion. Has anyone else ever had a bad reaction on their first dose?