Female-type question

I recall women writing in the past about applying Lugol's Iodine directly to the female genitalia, but it seems to me if one were to put 5% Lugol's directly on that tender part of the body, that it would be painful. Is there a concentration level of Lugol's Iodine that causes no pain or discomfort if directly applied, to say, the vulva or areas adjacent thereto ? Am I wrong in believing that the 5% causes pain or discomfort ? Thank you.