No. There may be a slight odor during the treatment but that is normal. It gives off no fumes. In some cases, not all, there may be a slight smell in the hair after the treatment, but this disappears after a few washes. To minimize this, be sure that the hair is rinsed as per the instructions and thoroughly dried before flat ironing. Even though this will disappear after the first few washes, it can be minimized or eliminated if the hair is thoroughly blown dry and not air dried.