الكي
Branding the skin with a heated instrument, named as effective but explicitly discouraged by the Prophet ﷺ in favor of other options — included here to show the tradition does not endorse every treatment it names.
الشِّفَاءُ فِي ثَلَاثَةٍ: شَرْطَةِ مِحْجَمٍ، أَوْ شَرْبَةِ عَسَلٍ، أَوْ كَيَّةٍ بِنَارٍ، وَأَنْهَى أُمَّتِي عَنِ الْكَيِّ
“Healing is found in three things: a cupping incision, a draught of honey, or cauterization by fire — though I discourage my community from cauterization.” (meaning, not a literal translation)
In another narration the Prophet ﷺ is reported to have said he disliked cauterization and did not like to use it (Sahih al-Bukhari 5725). This entry is worth reading alongside cupping specifically — both appear in the same three-part hadith, yet the tradition treats them very differently: cupping is described neutrally and practiced by the Prophet ﷺ himself, while cauterization is named only to be explicitly discouraged in the same breath, an unusually direct example of the hadith corpus distinguishing "effective" from "recommended."
Ibn al-Qayyim reads this as permission without endorsement — cauterization remained a recognized last-resort option in classical medicine, but a discouraged one given its pain and risk of harm, to be used only once safer options were exhausted. He notes reports of the Prophet ﷺ himself receiving cauterization on at least one occasion in his final illness, which commentators read as demonstrating that the discouragement was about preference and severity of harm, not an absolute prohibition.
Therapeutic cauterization has largely been superseded in modern medicine by more precise techniques (electrocautery under sterile clinical conditions, for genuinely different purposes than the historical practice), and is not something modern medicine recommends performed outside a clinical setting. Noted here as context on how far medical practice has moved from this specific historical method, not as a modern validation of the traditional technique.