Are you salt loading? Sometimes headaches can be avoided altogether with proper salt loading. And salt loading decreases all kinds of side effects, as well as tolerance to iodine.
As far as the dry mouth - I have noticed a general drying with iodine. I wonder if it is connected to mucous problems, which I have had in the past, as it is the same type of dryness as with an antihistamine. As far as detox symptoms go, we are affected by wherever we are weak. I have found that really large doses of vitamin A and cod liver oil help my mucous membrane problems.
Taking Iodine breaks helps too. I take one day a week.