Nilvembu kudineer is a concoction of nilavembu நிலவேம்பு, Andrographis paniculata, the chief ingredient, Vettiver வெட்டிவேர் (Vetiveria zizanioides), Vilamiccai ver விளாமிட்சை வேர் (Plectranthus vettiveroides), Canthanam சந்தனம் (Santalum album), Pey pudal பேய் புடல் (Trichosanthes cucumerina), Koraikkilanku கோரை கிழங்கு (Cyperus rotundus), Cukku சுக்கு (Zingiber officinale), Milaku மிளகு (Piper nigrum) and *Parpatakam பட்படாகம் (Hedyotis [=Oldenlandia] corymbosa OR Mollugo cervicana) (Pharmacopoeia of Hospital of Indian Medicine, 1995). This concoction is said to be effective in treating a diverse range of fevers.
In 2017, after the TN government started distributing the concoction, questions were raised about the scientific support for such action. There were a few studies, and they seemed to support effectiveness of the medication:
Anbarasu et al. 2011 Antipyretic, anti-inflammatory and analgesic properties of nilavembu kudineer choornam: a classical preparation used in the treatment of chikungunya fever. Asian Pacific Journal of Tropical Medicine (2011) 819-823 (pdf).
Tang et al. 2012 Screening of anti-dengue activity in methanolic extracts of medicinal plants. BMC Complement Altern Med. 2012, 12(3), 1-10.
Christian et al. 2015. Protective effect of polyherbal siddha formulation-nilavembu kudineer against common viral fevers including dengue – a case-control approach. Intl J Pharm Sci Res 40: 1656-1660
By 2019, there appears to be more support/approval for the practice and there are more scientific studies that point to plausible modes of action of the medication.
Panraksa et al. (2017) Activity of andrographolide against dengue virus. Antiviral Research 139: 69-78
Mattummal et al. (2018) Bioactive molecules in Siddha polyherbal Nilavembu Kudineer alleviating symptoms of Dengue/Chikugunya Traditional Medicine Research 3(5) Special Issue: SI 215-229
Ramalingam et al. (2018) Anti-dengue activity of Andrographis paniculata extracts and quantification of dengue viral inhibition by SYBR green reverse transcription polymerase chain reaction Ayu 39(2): 87-91
Paemanee et al. (2019) A proteomic analysis of the anti-dengue virus activity of andrographolide. 109: 322-332
Jain et al. (2019) Antiviral activity of ethanolic extract of Nilavembu Kudineer against dengue and chikungunya virus through in vitro evaluation. Journal of Ayurveda and Integrative Medicine.
*Parpatakam or Parpadagam (பற்படாகம்): Maybe any of these species according to Senthilkumar & Parani (2016): Mollugo pentaphylla/cercivana, Hedyotis corymbosa? (probably alternative used in southern states), Fumaria parviflora (probably the original, Himalayan) [D. Narasimhan, pers. comm.]