I don't believe its common for iodine to detox mercury. Dr Brownstein claimed this on a video and showed a chart where mercury increased substantially after iodine supplementation, but this was only a single patient, and if it was the norm then I'm sure he would have gotten more data by now to show that this happens in a lot of people who take iodine.

Bromine is detoxified by high doses of iodine, and Bromine inhibits lots of enzymes which mercury also does, so the symptoms of both can overlap and seem very similar.

I've had a lot of progress in the past few months from 50mg+ of iodoral or lugols, but still chelating Cutler style with alpha lipoic acid and DMSA to deal with mercury safely.

An interesting note, I wasn't able to tolerate any good dose of lugol's iodine until a full year of mercury chelation. The symptoms were just too awful to cope with. But after a year and some months of chelation I could tolerate high doses of iodine and its been making a big difference over the past few months.