Abstract
Background:
Suram (Fever) is a cardinal response of infection. Nilavembu decoction is used in the treatment of fever in Siddha Medicine and various clinical researches on Nilavembu decoction has reported significant efficacy against viral fever. Andrographis paniculata, Mollugo cerviana, Cyperus rotundus, Melothria heterophylla, Vetiveria zizanioides, Plectranthus vettiveroides, Santalum album, Piper nigrum and Zingiber officinale are the ingredients of Nilavembu decoction which are used in equal proportions while preparing decoction.

Aim:
To analyse the pharmacological activity of Nilavembu decoction and its individual plants based on which the drug is used in Suram through review in detail.

Materials and Methods:
The data were collected about Nilavembu decoction and its ingredients from Siddha text books and research publications through the PubMed, Research gate and Google Scholar. These data were tabulated and analysed.

Observations:
Febrifuge, diuretic, diaphoretic, alterative, stomachic and chologogue actions of individual plants of Nilavembu decoction have been identified through the literatures. All ingredients of Nilavembu decoction have antimicrobial, diuretic and diaphoretic actions. Through the review of reported previous studies, out of 9, 8 herbs have antimicrobial activity against Staphylococcus aureus. Vetiveria zizanioides and Zingiber officinale inhibited 10 types of microorganisms. Cyperus rotundus inhibits 9 types of microorganisms. 78% of plants inhibited both gram positive as well as gram negative bacteria.

Conclusion:
Based on the review analysis it can be concluded that Nilavembu decoction could be given in the fevers caused due to infective agents such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Bacillus sp.

Key words: Suram (Fever), Nilavembu decoction, Pharmacological activities