Siddha Medicine

Siddhars and the Tamil medical tradition

Within the tradition, Siddha medicine is attributed to the siddhars. The National Institute of Siddha (NIS), a Government of India institution in Chennai, says in a 2023 prospectus that the system evolved with the Indus valley civilisations of Mohenjo-daro and Harappa around 10,000 years ago, was developed mainly by 18 siddhars, and regards the sage Agasthiyar as its father. These are the institution's own statements of tradition, not independently dated findings. A historian's footnote glosses siddhars as people who sought a strong body in order to gain supernatural powers, using means that included mercurial drugs and yogic practices.

Part of the written record is held as palm-leaf manuscripts. A 2015 Endangered Archives Programme project (EAP810), run with the French Institute of Pondicherry, aimed to digitise Siddha manuscripts from a collection of about 150 texts and from traditional practitioners in northern, central and southern districts of Tamil Nadu, and reports that 1,586 manuscripts were digitised. The project page notes that palm leaves are vulnerable to insect larvae, rodents and fungus. The sources reviewed do not date individual manuscripts.

When Siddha became a separate system

Kanagarathinam and Lourdusamy (Medical History, 2023) accept that many Siddha practices have been in use for centuries, back to before the Common Era, but write that its origin as a separate system, in terms of identity formation, is more a twentieth-century phenomenon. They report that until about 1920 medical practice in the Tamil region was generally called Āyuḷvētam or Vaittiyam, mixed medicines, magic, yoga and astrology, and drew on both Tamil and Sanskrit texts.

They link the change to the Usman Committee, set up by the Madras government in 1921 to let exponents of the Ayurvedic and Unani systems state their case, and to the Dravidian political movement. Afterwards new Siddha associations replaced Āyuḷvēta titles with Tamil ones. They note that Rick Weiss reads this through Hobsbawm's idea of the invention of tradition, and argue that material incentives mattered alongside nationalism.

Colonial attitudes and modern institutions

The same authors cite Madras government records in which, before 1920, officials declined to fund indigenous medical schools, described hereditary teaching as lacking systematic method, and called such systems less scientific than European medicine. Those are colonial officials' judgements, not assessments of the medicine. The NIS in Chennai was dedicated on 3 September 2005, and its prospectus says a Bachelor of Siddha Medicine and Surgery programme with 60 places was approved there in 2022-23.

Siddha in Sri Lanka

A 2016 review in the Journal of Ethnopharmacology describes Siddha (Tamil) medicine as one of four traditional medical systems in Sri Lanka, practised mostly in the eastern and northern provinces where most Tamils live. The authors drew on historic and modern Sri Lankan university textbooks in Tamil. The sources reviewed give no further history for Sri Lanka.

Humoral and constitution terms

Siddha texts, as summarised by Muthiah and colleagues in 2019, describe three vital forces, Vali (Vatham), Azhal (Pitham) and Aiyam (Kabam), whose combinations form a person's body constitution, called udaliyal. The review, by authors at the Siddha Central Research Institute and a partner institute, counts seven udaliyal types according to which force dominates, and seven body constituents (sapthadhathu) including plasma, muscle, fat, bone, marrow and reproductive tissue. An NIS page spells the terms Vali, Azhal and Iyyam, so transliteration varies between sources.

The review drew on about 25 Siddha books, including titles attributed to Theraiyar and Agathiyar. Its stated purpose was to support a questionnaire for Siddha constitution assessment, so these are descriptions from the tradition's texts and not measured biomedical constructs.

Siddha, Ayurveda and Āyuḷvētam

In Tamil, āyuḷvētam combines ayus (life) and veda (knowledge), and Kanagarathinam and Lourdusamy use 'Ayurveda' for the Sanskrit system only after 1920. Until then Siddhars and physicians of the Tamil region used Āyuḷvētam for their own practice. A commentator in 1915 wrote that texts attributed to Agastiyar, Theraiyar and Pulippani were generally treated as Ayurvedic, while arguing that not all Tamil texts should be.

Scholars cited by the same authors, including Hartmut Scharfe, have debated whether Siddha derived from Ayurveda or the reverse. Shared vocabulary, such as three humours, does not by itself make the two systems equivalent, and this page describes Siddha concepts as the Tamil tradition presents them.

Assessment

An NIS page on diagnosis lists an eight-fold examination, Enn vagai thervugal: pulse (naadi), touch, tongue, complexion, speech, eyes, stool and urine. It adds wrist-circumference measurement, a five-bird theory and medical astrology among the tools described, attributes particular methods to named sages, and says 4,448 diseases were enumerated by the Siddhars. The page does not describe consultation length, and the sources reviewed give no typical session length.

Preparations and processing

A 2018 hospital series describes mercury as used extensively in Siddha preparations after purification. The authors of a 2026 case report describe traditional processing of metals, including mercury, mica, copper and arsenic, with herbs: calcination, detoxification by boiling in plant decoctions and urine, and grinding with herbal pastes. Ingredients in Sri Lankan antidiabetic preparations were reported as plants, animal parts including marine organisms, and inorganic substances.

Laboratory studies have tried to characterise individual preparations. A 2022 study of Thamira parpam, a copper-based preparation that its authors say has been used for centuries, found copper(II) oxide particles of 10 to 50 nanometres after following the traditional method. A 2024 study of a cinnabar-based drug compared two purification methods and measured metal content at each stage.

Varmam therapy

A 2025 case series describes varmam as a traditional Siddha technique using selected pressure points. In that series, 10 people with cervical spondylosis received varmam once every two days for 12 sessions, with pain and neck disability scored before, during and after. This is one study protocol. The sources reviewed do not describe how varmam is taught or practised more widely, and this page does not set out techniques.

Traditional and institutional claims

The NIS prospectus states that the system's basic principle is that food is medicine and medicine is food, that it relies on moral principles, and that it was able to save the lives of a number of acute, moderate and mild COVID-19 patients. The last is an institutional claim. The trials discussed below tested specific regimens and cannot be read as showing that the system as a whole saved lives.

Muthiah and colleagues say the classical literature gives guidance on identifying constitution types, dietary recommendations and disease susceptibility. The authors of the Thamira parpam study attribute an anti-ulcer use to that preparation in Siddha practice. These are claims within the tradition and are not evidence of effect.

Conditions that have been studied

Published Siddha studies address a range of conditions. Examples in the sources reviewed are COVID-19, studied with decoctions and add-on regimens; cervical and lumbar spondylosis, where Siddha accounted for 24.8% of 113 Ayush studies in one systematic review; and diabetes, for which a 2016 review documented 60 Sri Lankan Siddha preparations containing 171 plant species. That a condition has been studied does not mean the evidence supports a benefit.

A double-blind trial of two decoctions in COVID-19

Srivastava and colleagues (Trials, 2021) randomised people with mild to moderate symptomatic COVID-19 at one hospital in Greater Noida, India, to Nilavembu Kudineer, Kaba Sura Kudineer or a placebo of decaffeinated tea, each given as 60 ml twice daily for up to 10 days alongside standard treatment. Of 125 recruited, 120 completed. Mean hospital stay was 8.4 days with placebo, 4.7 with Nilavembu Kudineer and 4.2 with Kaba Sura Kudineer, and viral load measures also favoured the decoctions.

An open-label add-on regimen

In an open-label, single-centre trial of 200 hospitalised COVID-19 patients, a Siddha add-on regimen with standard care was compared with standard care alone (Christian and colleagues, 2023). Accelerated recovery within seven days occurred in 59.0% of the treatment group and 27.0% of controls (odds ratio 3.9, 95% confidence interval 1.9 to 8.0). The authors also report lower mortality in the treatment group, with follow-up to 90 days.

Varmam and plant studies

Evidence for varmam in the sources reviewed is a case series of 10 people with no comparison group, whose authors describe significant reductions in pain and disability and call for further studies. A case series cannot show that a change followed from the treatment and not from natural variation or other care. Sri Lankan antidiabetic plants reviewed in 2016 were mostly studied in animals: of 123 species assessed, 48% reached in vivo studies, 41% were unstudied or showed no antidiabetic activity, 6% reached in vitro and 5% clinical level.

What the searches found and did not find

A PubMed search on 5 October 2026 for Siddha with randomised, randomized or systematic review in the title or abstract returned 42 records. Among the titles screened were COVID-19 trials, trial protocols, case reports and laboratory studies. No systematic review of Siddha medicine as a whole and no randomised trial of varmam was identified. Other databases were not searched, so this is not a statement that none exists.

Design, funding and independence

The double-blind decoction trial named its small sample, single centre and short follow-up as limits. It was funded by the Central Council for Research in Siddha, an Indian government research body with which several authors are affiliated, and the authors declared no competing interests. The open-label trial had no blinding or placebo, and most of its authors are affiliated with the NIS, with one listing a Siddha manufacturer.

These affiliations are not evidence of bias, but the research was not independent of Siddha institutions. Large differences in an unblinded trial carry a risk of bias, and one trial cannot show that a result would be repeated elsewhere.

Limits on generalising from trials

The trials reviewed tested fixed formulations in COVID-19 during 2020 and later, while the classical texts describe assessment by constitution type. The trials therefore did not test constitution-based individual prescribing. Heavy-metal testing of the decoctions was not reported in the double-blind trial, and the open-label trial's keywords include a preparation named Maldevi chenduram whose composition the abstract does not state.

Metal poisoning case reports

Tan and colleagues (2026) report a 58-year-old woman who took unlabelled Siddha capsules daily for three months and presented twice with severe headache, vomiting, speech disturbance, tremor and ataxia, with brain swelling on imaging and a seizure on the second occasion. Her blood lead was 993 micrograms per litre against a reference below 100. The capsules held lead, mercury and arsenic at several hundred to tens of thousands of times the limits the authors cited. She improved after chelation therapy.

A retrospective hospital series (Gnanashanmugam and colleagues, 2018) describes 32 patients admitted between 2012 and 2016 with high blood mercury after taking Siddha medicines from unauthorised dealers. All had severe neuropathic pain, 81% had fasciculations or myokymia and 28% had features of encephalopathy. Such reports do not show how often harm occurs among all users.

Metal content in analyses

A 2021 scoping review of case reports of metal toxicity from Ayurveda or Siddha preparations found 220 cases, 156 involving lead, 47 mercury and 11 arsenic; 113 of 135 analysed samples exceeded permissible metal content. The authors attribute this often to adulteration or improper manufacturing and prescribing. It does not separate Siddha from Ayurveda, and Tan and colleagues write that Siddha has been less often implicated.

In a 2024 cinnabar study, lead, arsenic and mercury exceeded Ayurvedic Pharmacopoeia of India limits in the purified material and both finished drugs; one finished drug was within oral exposure values from ICH Q3D guidance and the other had slightly more lead. A 2022 rat study of Thamira parpam found no organ abnormalities, which its authors read as low-dose safety. Animal findings do not establish human safety.

Adverse events in studies

The double-blind trial reported two adverse events, a day of vomiting with placebo and a day of diarrhoea with Nilavembu Kudineer, and no serious events. In a 2024 systematic review of 113 Ayush studies for spondylosis, 24.8% Siddha, only 13% described adverse events, naming yoga, Unani and homoeopathy among them; the authors suspect underreporting. Absence of reports is not evidence that none occurred.

Training and care boundaries

The NIS prospectus says its Bachelor of Siddha Medicine and Surgery follows a curriculum approved by the National Commission for Indian System of Medicine, is affiliated to the Tamil Nadu Dr M.G.R. Medical University, and expects applicants to have studied Tamil. The sources reviewed do not describe registers or training standards in Ireland, the UK, the United States or Sri Lanka, and requirements differ by country.

The case reports involved unlabelled or unauthorised products, and diagnosis rested on blood and product testing in hospital. New neurological symptoms, severe pain or other concerning symptoms need medical assessment, and traditional preparations are not a basis for delaying or replacing necessary care. This information is educational and is not individual medical advice.