Offering medical treatment by means of cauterizing is permissible, as it has been authentically reported that the Prophet (peace be upon him) said,
If there is anything good in your medicine, it should be in the instrument of the cupper or drinking honey or cauterizing with fire that suits the ailment, but I do not like to be cauterized.
Sa`d (may Allah be pleased with him) was cauterized when he was wounded in his ankle because of an arrow that pierced his leg. However, it is preferable to abandon cauterization following the Prophet's saying,
But I do not like to be cauterized.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.