The Compendium of Caraka 6.17.120

6.17.120

ete hi kaphasaṃruddhagati-&prāṇaprakopajāḥ/
tasmāttanmārgaśuddhyarthaṃ deyā lehā na niṣkaphe//

For these [diseases] arise from the provocation of the vital breath whose passage is blocked by kapha; / therefore, these linctuses should be given to clear its channels, not when kapha is absent.