The jaina mantravAdins in the karnATa country use a medical text termed the hitopadesha. Its author is shrIkaNTha-shambhu or shrIkaNTha-shiva. This work is a rather distinctive one (at least to me) when compared with other standard tomes of Hindu medicine. In this work he appears as a classical Ayurvedic physician rather than a magician, although he does not really give any notable references to earlier medical authors or follow their systems too closely. He overemphasizes the trihumoral theory in a manner similar to several modern practitioners of Ayurveda. But interestingly he cites his main authorities as the “shivamata (in the section of urine analysis, samuddesha 1)” and “shambhudeva” (in the section on insect bites, samuddesha 8). He is also well aware of fevers caused by Tantric abhichAra prayogas. There is another obscure work by a shrIkaNTha-shiva paNDita that is called the yogaratnAvalI. This work is more tantric than medical in content. It has several recipes of rasAyana like those attributed to the earlier authority nAgArjuna. It also discusses fevers caused by the seizures by bhUta-s and shAkinI-s. It also mentions garuDa tantra-s and formulations from their tradition to counter viSha prayoga-s. While there is nothing available to connect the two shrIkaNTha-s who are authors of the above works, such a link is implied by the scholar Hymavathi from the Andhra country who has carried out a deep study of Ayurvedic history. As per Hymavathi this shrIkaNTha was a shaiva philosopher who was a teacher of mAdhava vidyAraNya, sAyaNa, bhoganAtha and the physician nR^isiMha paNDita. This may be based on material that I have no access to (one such could be the Nellore inscription). Irrespective of the situation, features in both these works and author’s name suggest that the shrIkaNTha (s) was associated with the siddhAnta srotas, even though his medical tradition was inherited by the followers of the nirgrantha.
Other lines of evidence also point to an interest in medical among the saiddhAntika-s. For example, the prati-viSha prayoga-s are listed by the late siddhAnta Tantric ishAna-shiva, some of which ultimately go back to the traditions of the garuDa tantra-s. The memory of saiddhAntika knowledge in a medical context also appears to linger on, long after the saiddhAntika-s ceased to be major players in the Indian intellectual sphere. This is seen in the bR^ihad-yoga-taraMgiNI, a voluminous work of the prolific smArta brAhmaNa, trimalla bhaTTa (early 1600s of CE), from south India settled in Kashi. This work adopts a considerably tantric approach to medicine and he cites various tantra-s including the shiva agama-s of the Urdhva-srotas, and tantras of the kubjikA tradition like manthAna-bhairava and siddha-lakShmIshvara tantra. The transmission of the tantric material from the siddhAnta tantra-s to trimalla bhaTTa appears can be traced back to an obscure medical work the kAlaj~nana that potentially belongs to the saiddhAntika tradition.
This prompted us to look more deeply into whether there were other associations to support the the link between the saiddhAntika-s and the medical lore. One name which immediately came to mind was the great medieval Hindu medical researcher shivadAsasena who wrote medical treatises such as the tattva-chandrikA. We do not know much about his life, but we known lived after bhoja-deva paramAra whom he cites repeatedly and also DalhaNa. While he mainly cites various medical authorities through out his works, we also note that he cites certain achArya-s named aghorashivAcharya and maheshvara who are not cited by authors of similar medical works. This observation, together within his name hinted that he might also be saiddhAntika (perhaps a putraka) who was active in medicine. To see if there might be more connections along these lines we looked deeper into this Hindu medical tradition. shivadAsasena in the opening of his tattva-chandrikA states that he is building upon an earlier medical work named ratna-prabha by the famous physician named nishchalakara from the va~Nga country. nishchalakara, while respectfully saluting his bauddha AchArya, is explicit in profusely invoking shiva-mahAdeva in his ma~Ngala. This suggests that he was also a shaiva, but I could not find anything specific in his ma~Ngala to suggest that he was specifically a saiddhAntika. However, he describes rasAyana procedures (shloka-s 167-190) in which he explicitly cites multiple times the tantra-s (or Agama-s) of shaiva-siddhAnta as his sources in this regard. He also mentions some obscure shaivAcharya-s such as ishAna-deva, umApati and shambhu as medical authorities whom he cites in different contexts. As nishchalakara specifically mentions that his patients included AstIka as well as nAstIka Tantrics, and he could well have been acquainted with their lore even if he was not a practitioner himself.
nishchalakara’s own work is based on the even earlier illustrious medical authority chakrapANi-datta from Meghalaya who composed several medical treatises: Ayurveda-dIpikA, chikitsA-saMgraha,vyagradaridra-shubhaMkara, bhAnumati and dravya-guNa. nishchalakara lists the works which were referred to by chakra and mentions shaiva-siddhAnta tantra as one of them. This prompted me to look in to the chikitsa-saMgraha. From his ma~Ngala and mention of the vedic ritual system of the mImAmsaka-s it clear that chakrapANi was a smArta, but definitely sympathetic and acquainted with the siddhAnta tradition. In describing a recipe for a drug in pill form called the shiva-guTikA, chakrapANi states that it was first taught by shiva to vinAyaka, and that this procedure is derived from the shaiva siddhAnta tantra-s. In fact, as far as I can see, these siddhAnta tantra-s are the only tantric sources named as authorities consulted by both chakra and nishchalakara. Most remaining texts cited by these authors are specifically medical works, dietary, chemical or general works (e.g. va~nga-deshIya gandha-shAstra, i.e. the text on perfumes of Bengal). Another possible sign of the saiddhAntika influence on the chakrapANi and possibly even his predecessor, the learned physician bR^inda from Varendra, is the prescription of two yantras in their work known as ubhaya-trimshaka and ubhaya-pa~nchadashaka, both of which are encountered in identical form in the chidambaraM paddhati-s of saiddhAntika-s from the drAviDa country. This suggests that even if these authors were not saiddhAntika-s themselves they were definitely influenced by the Urdhvasrotas and the saiddhAntika-s did support a medical tradition within their system.
Examining some of the apparently earlier saMhitA-s of medicine does not show any specific references to the siddhAnta tantra tradition even if they might contain several allusions to the worship of shiva in a general sense or from other srotas. For example: 1) The harita saMhitA contains a ma~Ngala to shiva and a reference to shiva dhyAna. 2) The bhela saMhitA mentions the worship of vR^iSha-dhvaja but also specifically mentions the use of the bhUta tantra-s (pashchima-srotas) in countering the effects of graha-s. Thus, it appears plausible that the saiddhAntika interaction with medicine began developing in the post-gupta period which saw the rise of saiddhAntika advisers in many Indian kingdoms. From the evidence it appears quite possible that some saiddhAntika-s took to the study of medicine as a part of their repertoire of “secular” services. At the same time they also appear to have introduced some practices peculiar to the shaiva systems into the medical system, such as the preparation of certain guTika-s and rasAyana-s and also use of yantra-s. This was not particular surprising given the matrix of earlier connections seen amongst the shaivas: 1) Right from the veda rudra is the bearer of medicines (practically all R^igvedic sUkta-s to rudra contain an allusion to his bheShaja-s). 2) The vedic medical tradition develops in the atharva veda. The connection of the early pAshupata-s with the atharvavedic tradition probably resulted in them inheriting the medical systems of the AV. This was probably transmitted to their successors the saiddhAntika-s and also other major shaiva groups like that of the pashchima-srotas, garuDa srotas and offshoots of the dakShINa-srotas.