In Siddha medicines are based mostly on herbs and metallurgy. Metals are converted by them into medicinal compounds in powder form or solid components of high potency. Some Siddhas make use of a saltish substance ('muppu' or universal salt), to prepare medicines. This universal salt is capable of rejuvenating the entire human system. Siddhas dealt with metals, salts, minerals and animal products. 

       Fractures of the bone are set right by traditional bone -setters, who have learnt the art orally from generation to generation. It is a separate science prescribed by the Siddhars. It is known as 'Varma Treatment' by them. It deals with the various kinds of fractures and their cure.

       There are about 64 types of medicines in Siddha. The common preparations are Bhasma (calcined metals and minerals), Churna (powders), Kashaya (decoctions), Lehya (confections), Ghrita (ghee) and Taila (oil).

       Oil is used for external application by Siddhas. Bathing regularly after being anointed in the oil (in which the essence of the herb 'Karisilanganni' is added) is an antidote to skindiseases.  For body pain, Marma Thailam, an oily preparation from herbs is applied to the body before going to bed. After a hot bath in the following morning, symptoms of relief are said to be marked.

      Herbs are used to treat asthuma. According to mythology, some of the herbs are stated to have the power to transform old men into youth. 

      Powdered gold, silver and other metals extracts from pearls and corals, and juices of herbs are made use of by the manufactures of Siddha medicines. Even today, people are said to consume 'Thanga Bhasmam' or powdered gold to get over the handicaps of old age.