Thyroid nodules are extremely common and usually entirely harmless. A thyroid nodule is simply normal thyroid tissue that has grown abnormally to form a nodule. Nodules sometimes form in places on the thyroid gland where they can actually be felt by the person, while at other times they may be located in a part of the gland where they are entirely unnoticeable.
You haven't mentioned how your sister knows that she has nodules on her thyroids. If she found out due to the presence of any other symptoms, then there may be cause for concern. However, the existence of the nodules by themselves is nothing to worry about. By some estimations, at least half of all adults have or have had thyroid nodules at some point in their lives. An overwhelming majority of the nodules is benign.
Some thyroid nodules are however cancerous. Some grow large enough to cause problems with swallowing, speaking, and breathing. In some cases, nodules may also produce excessive amounts of the thyroid hormone. Your sister should visit a doctor to determine what kind of nodules she has, particularly if she is experiencing any other symptoms. There is no way to simply "dissolve" the nodules, using either medical treatment or herbs.
answered by G R