Every since my radioactive iodine treatment after thyroid cancer i have had bad acne. could this be related? i had the treatment in june of 2010.

Indirectly related: It would be very unlikely for the radioactive iodine to induce acne, but another change that probably happened around the same time is taking thyroid hormone. Thyroid hormone tablets could affect the balance between estrogen and testosterone, by changing the amount of sex hormone binding protein made by the liver. Lab tests could help your doctor know if this was causing your acne.

Not usually: Radiation dermatitis is usually a result of external beam radiation, and not from taking radioactive iodine. The iodine is concentrated in the thyroid gland, but can also be stored in the salivary glands. However, acne is not usually a side effect. If you are young, acne may just be part of normal development. Using mario badescu drying lotion may help (as long as you don't have allergies).

Thyroid function: Please make sure your thyroid function tests are normal. Also, without knowing your age, if you had thyroid cancer at a younger age, acne may just be related to adolescence.

Acne: Unlikely to be related. Acne is usually mediated by either skin issues or androgen stimulation of hair follicle. Don't see relationship to thyroid.