Sushruta Samhita
तथा मर्मसिरास्नायुसन्धितरुणास्थिसेवनीधमनीगलनाभिनखान्तःशेफःस्रोतःस्वल्पमांसेषु च देशेष्वक्ष्णोश्च न दद्यादन्यत्र वर्त्मरोगात् ॥२९॥
Similarly, alkaline treatments should not be applied to regions with vital points, veins, nerves, joints, or where the skin is thin, where there is inflammation, or where there is very little flesh. They should also be avoided in cases of injuries or infections along the pathway of the treatment.
english translation
tathA marmasirAsnAyusandhitaruNAsthisevanIdhamanIgalanAbhinakhAntaHzephaHsrotaHsvalpamAMseSu ca dezeSvakSNozca na dadyAdanyatra vartmarogAt ॥29॥
hk transliteration by Sanscript