Iodine does not "cause" acne, but it DOES cause bromine/bromide to be released from your tissues.
Bromine being released through your body causes frontal lobe headaches, brown urine, various levels of brain fog/lethargy....and skin rashes & various 'acne' type skin conditions as the bromide comes out of the body.
Iodine has been associated with CAUSING acne, but it's actually the toxins coming out that the Iodine releases that is the cause.